Note
20 October 2004 Elsam Engineering A/S Our ref. HHA/AAH/AWK Doc. no. 200128 Project no. T012063
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Verified: AWK Approved: HHA
Life Cycle Assessment of offshore and onshore sited wind farms.
This report is a translation made by Vestas Wind Systems A/S of the Danish Elsam Engineering report 186768 of March 2004 written in Danish.
In matters of doubt the Danish version applies
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Contents:
1. Introduction...... 5 1.1 Goal ...... 6 1.2 Objective...... 6 1.3 Target group...... 6 1.4 Method...... 6 2. Scope...... 7 2.1 Functional unit...... 7 2.2 Lifetime ...... 7 2.3 Life cycle stages...... 7 3. Offshore wind farm...... 9 3.1 Electric power generation ...... 10 3.2 Operation ...... 11 3.3 LCA model ...... 12 4. Onshore wind farm...... 13 4.1 Electric power generation ...... 14 4.2 Operation ...... 14 4.3 LCA model ...... 14 5. Data collection...... 15 5.1 Procedures for data collection...... 16 5.1.1 Workshop about reuse ...... 16 5.1.2 Allocations ...... 17 5.1.3 Manufacturing of turbines...... 17 5.1.4 Manufacturing of onshore foundation...... 21 5.1.5 Manufacturing of offshore foundation...... 21 5.1.6 Manufacturing of internal farm cables to offshore wind farm...... 23 5.1.7 Manufacturing of transformer station to offshore wind farm ...... 23 5.1.8 Manufacturing of 150 kV PEX submarine-/onshore cable and SF6-system for offshore wind farm ...... 24 5.2 Incoming materials ...... 25 6. Life cycle impact assessment...... 26 6.1 Environmental impacts ...... 26 6.2 Calculation method...... 27 6.3 Results...... 27 6.3.1 Statement of resource consumption ...... 27 6.3.2 Environmental impacts of 1 kWh ...... 29 6.3.3 Environmental impacts divided on life stages...... 30 6.3.4 Environmental impacts divided on components ...... 31 6.3.5 Comparison with Danish electricity ’97...... 33 6.4 Interpretation of results...... 33 6.4.1 Improvement strategies...... 34 6.5 Energy balance ...... 38 6.5.1 Energy consumption...... 38 6.5.2 Energy balance...... 40 6.6 Environmental Product Declaration...... 41 6.6.1 Environmental Product Declaration –Methodological requirements in the Nordic region.42
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6.6.2 Data quality for V80-offshore wind farm Environmental Product Declaration ...... 42
6.6.3 Environmental impact categories used in this Environmental Product Declaration...... 42
6.6.4 LCA-method and system delimitation ...... 43 7. Sensitivity assessment...... 44 7.1 Energy production ...... 44 7.2 Energy consumption...... 46 7.3 Location ...... 46 7.4 Lifetime ...... 48 7.5 Recycling ...... 50 8. Shortcomings...... 52 9. Conclusions...... 53
Appendix
Appendix 1. Main components
Appendix 2. Danish Environmental Declaration of Contents
Appendix 3. Energy balance
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Summary This report makes up the final reporting for the project “Life cycle assessment (LCA) of turbines – Analysis of possibilities of product directed environmental optimisation” effected by Elsam Engineering A/S and Vestas Wind Systems A/S financed by Elsam Engineering’s work through the Danish Energy Authority’s energy research programme for year 2000 (ERP2000). Vestas Wind Systems A/S financed its own participation in the project.
The purpose of the project is to carry through a life cycle assessment of an offshore wind farm and an onshore wind farm, respectively, as a basis for assessment of environmental improvement possibilities for wind farms through their life cycles. Likewise, the results are used to elaborate an environmental declaration of contents for power delivered to the grid from both types of wind farms.
The project has been running concurrently with a project about environmental assessment of future turbines, which RISØ is carrying out. Due to similarities between the two projects and the fact that RISØ’s project supplements the LCA-project in more ways, cooperation about the projects has been going on through the process, in the form of exchange of experiences and results. In cooperation with RISØ, Elsam Engineering and Vestas Wind Systems A/S have carried through a workshop about dismantling and removal of wind farms. In that connection, we would like to address our gratitude to RISØ for their help in planning and carrying out the workshop.
The project states the environmental impact for electricity produced at Horns Reef offshore wind farm and Tjæreborg onshore wind farm, respectively, as representatives for contemporary Danish offshore wind farms and onshore wind farms, respectively. Tjæreborg onshore wind farm is placed at an utmost favourably location with regard to wind, which means that the production at this wind farm is high compared with other onshore wind farms in Denmark. The high production rate is a factor that is taken into account when assessing the impact on the environment emanating from this wind farm.
The results of the environmental life cycle assessments that have been carried out for the two wind farms do not show significant variance. If it is taken into account that Tjæreborg onshore wind farm is placed utmost favourably, the comparison shows that power from an average located onshore wind farm would have a more adverse or corresponding environmental impact as an unfavourably located offshore wind farm.
The results show that it is the turbines that causes the largest environmental impact and not to a very high extent the transmission grid. For the turbines, the all-important environmental contribution comes from manufacturing and removal of the turbines, as it is the materials that cause the large environmental strain. The operation of the wind farms gives practically no contribution to the total environmental impacts. The foundations of the offshore wind farms make up a considerable factor to the total environmental impacts, as steel is a large constituent part of the foundations, some of which is abandoned at the seabed after dismantling of the farm. Therefore, the foundation of the offshore wind farms is selected as a focus area in connection with possibilities of product optimisation. Other types of foundations are assessed, and it is found that all the assessed foundation types give the same environmental impact, even though one of the types (caisson) will be completely removed from the seabed whereas in the case of other types (mono pile and tripod) everything more than 1 metre below the seabed is abandoned.
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Even though the operation does not contribute considerably to the environmental impacts, the environmental differences in using helicopter contra boat at maintenance of the offshore turbines have been examined. The differences are significant, as servicing by boat is insignificantly small. But irrespective of the way of transport the servicing will not contribute largely to the total impact from the entire farm in the total lifetime.
1. Introduction
This report makes up the reporting in connection with the project “LCA of turbines – Analysis of possibilities of product directed environmental optimisation”.
The project is carried out in cooperation between Vestas Wind Systems A/S (hereafter called VWS A/S) and Elsam Engineering A/S.
VWS A/S has financed its own part of the project, while the Danish Energy Authority’s energy research programme (ERP) has paid Elsam Engineering’s part.
In the year 2001 VWS A/S and Elsam Engineering A/S completed a design scheme, in which a life cycle assessment was elaborated of a Vestas V80 2.0 MW turbine, which is used as basis for this life cycle assessment.
Life cycle assessment (LCA) is a method to assess the environmental aspects and potential impacts of a product. LCA is a tool that is used to give a technical estimate of the environmental consequences of products and activities. The LCA does not include the financial and social factors, which means that the results of an LCA can not exclusively form the basis for assessment of a product’s sustainability.
It also means that an LCA does not give detached, scientific and final answers as to the environmental properties of a product, as an LCA does not include all the impacts on the surroundings caused by a product in connection with use (e.g. noise, use of area, impact on animal life, etc.) To obtain a more complete environmental description, LCA must be combined with other environmental assessments as for instance environmental consequence assessments (e.g. Assessment of Impact of the Environment, AIE), risk assessment and environmental management.
LCA is a good tool to provide an understanding of environmental properties of a product and in many cases it can be used internally in companies as a part of the product development.
Some of the most essential limitations of LCA are:
• Many selections and assumptions are to be made (e.g. selection of system boundaries and data sources), which might be subjective. • The accuracy of an LCA will depend on the access to or the existence of relevant and liable data. • Models used for mapping or assessing the environmental impact are restrained by their conditions and will not necessarily be accessible for all potential impact categories or applications.
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1.1 Goal
The purpose of the project has partly been to use life cycle assessments to environmental improvement strategies in connection with product development and partly to use LCA-data for preparation of an environmental declaration of contents for electricity produced on turbines. At the same time, the purpose of the project has been to work for a wide understanding of environmental declaration of contents and to influence the turbine trade ensuring concepts for a trade standard for environmental declaration of contents of turbines/electricity produced on turbines.
1.2 Objective The objective of the project can be divided in three sub-objectives: 1. Preparation of an LCA for an offshore sited and an onshore sited Vestas turbine, respectively, including grid connection. 2. Consideration of improvement strategies for every one of the life stages: Manufacturing, use and removal. 3. Preparation of an environmental product declaration (EPD) of the two turbine types and of electricity produced through these.
1.3 Target group This life cycle assessment is directed primarily to two target groups. :
• The Danish turbine industry, including employees in VWS A/S’ departments of environment and improvement of an integration of environment in the product improvement. • The interested public including the Danish Energy Authority shall be able to use the overall results as part of an assessment of the turbine’s environmental characteristics.
1.4 Method This LCA is carried out and reported according to the principles of ISO 14040-14043.
ISO 14040 deals with “principles and framework” and determines the overall frames, principles and requirements to establishment and reporting of LCA’s.
ISO 14041 “goal and scope definition and inventory analysis” together with ISO 14040 determine the requirements and procedures necessary for the data collection and improvements of objectives and delimitation of an LCA and also the establishment, interpretation and reporting of the mapping of a lifecycle.
ISO 14042 “life cycle impact assessment” specifies requirements for the execution of the assessment of environmental impacts in the life cycle and relation between this and the other steps in the LCA.
ISO 14043 “life cycle interpretation” determines requirements to and recommendation of the interpretation of results of a life cycle assessment or life cycle mapping.
For modelling, the Danish Environmental Authority’s pc-tool is used, based on the UMIP-method. UMIP is an abbreviation for environmental design of industrial products. (UMIP) is selected because Elsam Engineering has created an extensive database with materials, environmental impacts etc. and is already experienced when it comes to using the tool.
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2. Scope The selected turbine type is a Vestas V80 2 MW turbine, as in the scheme design. In this project, however, both an onshore and an offshore sited wind farm are dealt with. The V80 turbine will be a little unlike for the 2 locations. The most essential difference is the tower height, but to this comes some smaller differences in the nacelle. The foundations are not produced by VWS A/S, but as for the two turbine locations the foundations differ considerably from each other, see more detailed descriptions in chapters 3 and 4. Main data for a V80 turbine is to be seen from Table 2.1.
Offshore turbine Onshore turbine Tower 140 t (60 m high) 165 t (78 m high) Nacelle 64 t 61 t Rotor 38 t 37 t Foundation 203 t 832 t Table 2.1: Main data for turbines for offshore and onshore sited farm, respectively.
2.1 Functional unit The functional unit is selected as1 kWh electricity produced on the selected turbines. Therefore all the impacts are estimated for this functional unit, which makes the results comparable with the results from the LCA for other electricity production technologies.
2.2 Lifetime The lifetime of turbines and internal cables is 20 years, while for transmission cables, transformer stations and cable transition station the lifetime is 40 years. Still it is expected that the operation of the turbines as a principle will continue more than 20 years, but there is no certainty for this.
When Elsam calculates financial circumstances of wind farms, it is based on the expected lifetime of 20 years. When the transmission grid is set to have an expected lifetime of 40 years it is based on the assumption that after 20 years lifetime of the farm, another farm will be erected or the existing will continue the operation for another 20 years.
2.3 Life cycle stages The life cycle of includes production, transport, erection, operation, dismantling and also removal of turbines, foundations and transmission grid. This is illustrated by the following figure with the attendant explanation of the specific life stages.
Production of Transport to site Operation. Dismantling and turbine farm and erection including scrapping components maintenance
Figure 2.1: Stages in the life cycle.
Manufacturing: Manufacturing includes the manufacturing of foundation, tower, nacelle and blades for offshore and onshore turbines and also the manufacturing of parts of the transmission grid.
Transport and erection: Transport from factory to erection site. This includes transport by truck (+ escorting car(s), in case where these are used) and transport by vessel at
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sea. Furthermore, transport of certain large components from sub-
contractors to VWS A/S is included in the model.
Erection includes crane work and other construction work at site.
Operation and maintenance: Change of oil, lubrication and transport to and from the turbines are included in the stage of operation and maintenance. Furthermore, renovation of gear and generator are included. The transport onshore is by truck, while at sea both vessels and helicopters are used.
Dismantling and scrapping: This includes cranage for dismantling, transport from erection place to the final disposal (by vessel at sea and onshore by truck + escorting car(s), where necessary). Furthermore, the further handling of the materials is included, either by recycling or by deposit. The modelling is limited to the point where the material is ready for reuse. This means for instance that shredding and a certain loss to waste are included, while the manufacturing in itself is left out.
A more detailed description of the wind farms and the included materials are presented in the following chapters.
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3. Offshore wind farm The offshore wind farm in this LCA-study is exemplified by the planned offshore wind farm at Horns Reef, established by Elsam in 2002. The reason for this choice is firstly that the farm will be regarded as representative for offshore wind farms to be established these years. Secondly, the farm is owned by Elsam and is planned by Elsam Engineering, thus, access to farm data is relatively easy to achieve.
The Horns Reef wind farm is placed in the North Sea approx 14 km from the coast of Blåvands Huk. The cable is to be connected ashore at Hvidbjerg Strand (seashore). For sketch of the farm complete with onshore connection cable, see Figure 3.1.
Figure 3.1: Sketch of Horns Reef wind farm including connection cable to Hvidbjerg Strand.
The farm consists of 80 Vestas V80 2 MW turbines erected in lattice pattern with a mutual distance of approx 560 metres. The depth of the water in the area is between 6.5 and 13.5 metres at mean sea level. The turbines are erected on mono pile foundations.
A sketch of the foundation types are seen from figure 3.2. When designing the farm, it was assessed which of the three Windfoundation types ‘mono pile’, ‘caisson’ or ‘tripod’, would be the best at Horns Reef. The mono pile is the cheapest of the three foundations, and due to the conditions at Horns Reef, e.g. a uniform sand bottom, it is possible to ram down the mono piles into the seabed. Besides, all other technical criteria can be fulfilled with mono pile foundation. Therefore, the mono pile is the preferred foundation for Horns Reef.
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Figure 3.2: Optional foundations for the turbines at Horns Reef. Mono pile is selected.
The foundations have a diameter of approx 4 metres and are rammed down approx 25 metres into the seabed. Between foundation and tower there is a transition piece for counterbalancing the diameter. On every transition piece, a boat platform is mounted,. This platform is used when the turbines are visited by boat.
The turbines are mutually connected by a 32 kV cable grid, which is assembled on the transformer station. At the transformer station, the produced energy from the wind farm is gathered and carried on to the shore. The transformer station is placed north-east of the offshore wind farm and consists of transformer, foundation, platform and internal cable.
The foundation of the transformer platform, which has a lifetime of 40 years, consists of three piles; two of these have a diameter of about 1.6m and one has a diameter of 2.3m. The three foundation piles are mutually combined by lattice girders.
3.1 Electric power generation The electric power generation from Horns Reef wind farm is stated to 647 GWh/year1, i.e. that each turbine produces 8.088 MWh/year, corresponding to 4.044 full loaded hours/year. These figures originate from recognized calculations of electric power generation and express a conservative assessment.
This figure indicates the turbines’ production of electricity to be delivered to the transformer stations including the grid loss that might be in the internal cables on the farm. From the transformer station to connection to the existing transformer onshore, however, there is a grid loss in the transformer and the cables stated to 10 GWh/year for the total farm. Approx 10% of this loss goes from the transformer2.
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Net loss:10GWh
Horns Horns Reef 32/150 kV Connection Reef Wind Wind Farm 647GW transformer 637GW to Farm annual station & transmission production 150kV cable line 637 647 GWh 637GWh GWh
Figure 3.3: Creation of system for LCA-model of Horns Reef.
3.2 Operation In connection with operation of the turbines, wear and tear will take place especially of the rotating parts. The turbines are dimensioned and constructed to a lifetime of minimum 20 years. To be on the safe side in this environmental assessment, a conservative estimate situation of maintenance of the turbines is assumed. It is expected that during the lifetime of 20 years one reconditioning/renewal of half of the gears and the generators is to be undertaken, which, as a minimum, is expected to comprise a renewal of the bearings. To simplify the model of operation, only the gearboxes have been included, but in return the model comprises a total renewal of half of the gearboxes once in the turbine’s lifetime. Thus, the model should now include an abundant amount of materials, as several of the gears and the generators will probably be repaired and not renewed. Moreover, the gearbox is significantly heavier than the generator.
In addition, materials for servicing of the turbines are included in the form of change of oil and lubrication of gear, generator etc.
The foundations of the offshore turbines are given cathodic protection as rust prevention, i.e. an active anode is used, which in this case is aluminium. This protection implies that aluminium is consumed through the lifetime. This is included in the operational stage.
Paint repair and renewal of active anodes to the cathode protection must be carried out at the transformer station after an operation time of 10-15 years. Further use of resources or materials is not included. It is estimated that inspection will be carried out 12 times a year. 9 of these are expected to be carried out by helicopter and the remaining 3 by boat. Inspection will also include about 2.400 km a year by car.
Regular inspection of the cables at the offshore farm is not included. However, the turbines are expected to receive servicing 5 times a year, which in 4 cases will be by helicopter and one time by boat.11
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3.3 LCA model
The model includes the turbines, the internal cables, transformer station offshore, sea cable, cable transmission station onshore and onshore cable to the existing grid. Each of these includes materials, manufacturing, transport, erection, operation, dismantling and scrapping. Figure 3.4 shows the elements included in the LCA model for Horns Reef wind farm.
Horns Rev Wind farm 150 kV transformer Cable transmission station Not included in LCA)
SF6 site 32 kV sea cable 32 kV seacable 150 kV seacable 150 kV seacable
System limit
Figure 3.4: Sketch of structure of Horns Reef offshore wind farm with statement of system boundaries for the LCA.
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4. Onshore wind farm The planned Tjæreborg wind farm is selected as an example of an onshore wind farm. The turbine type is a V80 2.0 MW turbine, but in this case the turbine type is for onshore placement.
Figure 4.1: Placement and organisation of Tjæreborg wind farm. The existing turbines are marked with black, and the new turbines with red.
In 2002, an onshore wind farm consisting of 8 turbines of various types with an effect of between 1.0 and 2.5 MW was established in Tjæreborg. One of these is a Vestas V80 2.0 MW turbine. A farm of this size is considered as a realistic size of an onshore wind farm with 2 MW turbines in Denmark.
Therefore, the onshore wind farm is modelled as a farm with 8 Vestas V80 2.0 MW turbines.
All the turbines are connected to the existing distribution grid in a 10/60 kV transformer station. The cables combining the turbines internally and to the transformer station are 10 kV cables. All cable extensions will take place in the soil. A new 10kV cable for the 4 new turbines will be established, as the existing electricity grid between the turbines in Tjæreborg can not lead to an additional effect of 8-10 MW. See Figure 4.3, for a principle sketch of Tjæreborg onshore wind farm.
In Tjæreborg, there will be a total of 8 km of 10 kV cable for connection of all 8 turbines to the existing transformer station. The turbines are to be erected on concrete foundations. Each turbine foundation is established in connection to a road, working and turning area. The size of the foundations is dependent on the geotechnical conditions. Normally, the traditional bottom plates are approx 15 × 15m wide and 2m deep. In total, approx 400m3 of reinforced concrete.
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The below figure shows a principle design of a bottom plate
Figure 4.2: Principle sketch of bottom plate for onshore turbines.
An access road is made with surface structure of gravel or any other approved road-making material.
4.1 Electric power generation A production calculation for the 4 new turbines in Tjæreborg is carried through, on condition that it is Vestas V80 2.0 MW onshore turbines. If the result of the production calculation aggregated with production data for the existing 2 MW turbine in Tjæreborg is used, it is found that the production from each Vestas V80 2 MW turbine is 5,634 GWh/year, corresponding to 2,817 full load hours. This is a quite high performance for an area onshore and corresponds to one of the best locations onshore in Denmark. In the sensitivity assessment calculations will be elaborated to assessment of the other onshore locations.
Losses in the cables are not calculated, as the loss is insignificant little, as to the fact that the cables are very short.
4.2 Operation Regarding maintenance of the turbines a conservative estimate includes that half of the gearboxes are to be renewed after 10 years. In addition, change of oil, lubrication of gear and generator etc. are to be included. Twice a year, a technician must go to the farm for carrying out surveillance of turbines and cables. Therefore transportation by car 900 km/year through the lifetime of the farm has been included in the model.
4.3 LCA model In the model of the onshore wind farm, materials, manufacturing, transport, erection, operation, dismantling and scrapping of turbines and internal cables are included.
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Tjæreborg Turbine farm Vestas V80
10/60 kV transformer (Not included in LCA)
10 kV PEX onshore cable
System limit
Figure 4.3: Grid connection system for Tjæreborg wind farm and statement of system boundaries of the LCA.
The lifetime of the turbines and the internal cables are set to be 20 years. VWS A/S states that the lifetime of onshore turbines is 20 years, and Elsam uses 20 years in the financial calculations. The turbines will probably be operating for several years but in the course of time the frequency of reparation and maintenance will increase, which may be a sign that after all the turbines will be taken out of operation after 20 years.
5. Data collection The collection of data has taken place in a very close co-operation with VWS A/S, so all information has been discussed with VWS A/S, and all assumptions of and approaches to materials and processes have been submitted and discussed.
As regards the transmission part to the offshore wind farm, there has also been a close co-operation with Eltra, who has delivered data to this part.
Concerning the turbines, the most significant environmental impacts will most typically arise during the manufacturing of the turbines and also the removal of the individual components, when the turbine shall be scrapped. On the other hand, the operational stage does not contribute significantly to the environmental impacts. Therefore the data collection has been concentrated in procuring as precise data as possible for the production and dismantling stages. To ease the model construction, the turbine system is divided into the component systems: • tower • nacelle • blades • foundation • internal cables • transformer station (off shore wind farm) • onshore bringing (offshore wind farm).
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At the data collection, the target for included materials has been to cover approx 95% of the turbine’s weight, as it has previously been proven that manufacturing of the turbine causes the major part of the environmental impacts in the whole life cycle of the turbine3. This has also been the target in connection with data for the other parts of the farms. In connection with LCA-data for the used materials, it has been attempted to cover 95% of what regards all 1st level materials (i.e. materials used on VWS A/S factories, e.g. PrePreg for blades and steel for towers). As regards 2nd level materials (i.e. materials used by the sub-contractors, i.e. paint and content of substances in PrePreg) it has been a question of prioritising the selection of materials of which it has been important to collect information.
5.1 Procedures for data collection The data collection for the turbines has mainly been carried out by VWS A/S on the basis of the item lists for the two turbine types and drawings of various components. The item lists are brought up from the company’s production management system, which furthermore contains information about material and weight of a very large part of incoming raw materials and semi-manufactured articles. As a starting point, all the item numbers on the item lists are included. As regards the items, where the information has not been immediately accessible it is assessed in each case whether it would be relevant to search for further information about weight and material composition. This has, among other things, caused that quite many screws and bolts and also minor electronic components have been unlisted. As regard large items as e.g. gearbox and generator, the information originate from the supplier.
Information about overall conditions for the farms, transmission, foundations, electric power generation and for some part operation and maintenance is mainly gathered from Elsam and Elsam Engineering, who are owner and owner's consulting engineer, respectively. In all instances, the information is presented to and discussed with VWS A/S. Information about the transmission from the offshore wind farm is drawn from Eltra, as owner for this.
Where possible the information about various materials is drawn from the database to UMIP, which have been extended through Elsam Engineering’s work with LCAs during recent years. In cases where LCA- data was missing or the existing data has been inadequate, these data are searched through suppliers, internet and other LCA-studies. In some incidents, it has been necessary to make assumptions about the materials. The assumptions will be described in the individual sections below.
5.1.1 Workshop about reuse As part of the project a workshop has been held about the dismantling of the turbines and removal of components/materials. Participants in the workshop are people occupied with dismantling, removal and recycling. Besides VWS A/S and Elsam Engineering, the following parties were represented: H.J. Hansen (occupied with dismantling, recovery and electronic waste, Demex (occupied with dismantling), Waste Centre Denmark and RISØ, who is working with assessment of future turbines in life cycle perspective.
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The work of this project contains the following removal scenario:
Material Scenario Steel 90% recycling Cast iron 90% recycling Stainless steel 90% recycling High-strength 90% recycling steel Cobber 90% recycling Aluminium 90% recycling Lead 90% recycling Glass fibre 100% deposit PVC-plastic 100% deposit Other plastic 100% incineration of waste Rubber 100% incineration of waste Table 5.1: Removal scenario for materials
The above mentioned scenarios of removal data derive from literature data and from the workshop about recycling. However, some of the experts from the recycling industry expressed that the loss by recycling steel and metal is less than the 10%, which are used in several cases. The reason why the 10% is maintained is that there is much uncertainty about the figure and at the same time it is not known exactly if all materials can be divided totally, i.e. there might be a loss, before the recycling process is started.
5.1.2 Allocations As turbines only produce electricity and no heat, there is no need for allocation between more products. This simplifies the inventory.
5.1.3 Manufacturing of turbines
5.1.3.1 VWS A/S’ energy consumption VWS A/S’ energy consumption for manufacturing turbines is set in connection with its Environmental Statement for 2001 (which not was published at the time when the collection of data ended) and indicates the total energy consumption in VWS A/S’ factories and offices. The energy consumption is stated as a key figure of the energy, which may be produced through the lifetime of the turbine (20 years), on all turbines manufactured at VWS A/S in 2001.
The energy consumption covers the total consumption for all buildings and processes. So it has not been possible to divide the energy consumption among the individual turbine components. However, it is included as a total consumption of manufacturing of one turbine. The energy consumption includes electricity, heat, oil and gas. The allocation between these various energy forms is given by VWS A/S, who publishes the numbers in the Environmental Statement for 2001.
VWS A/S has entered a purchase agreement about electricity for 2001, where the total free part – 54% - is purchased from renewable energy sources, i.e. CO2-neutral, whereas the mandatory part - 46% - (prioritised production), which VWS A/S must buy, as 2001 was expected to consist of 44% renewable energy – primary wind power. I.e., of the total electricity consumption 74% is from CO2-neutrale energy sources.
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The division of electricity used by VWS A/S has been taken from the expected division as shown in the
Environmental Statement for 20004, as the new numbers were not available. The division of electricity consumption regarding production methods are as follows (it is also indicated, how the individual systems are modelled in UMIP):
Energy system Share Modelled as Not prioritized electricity: - water power 54% Norwegian electricity 1990 (99,7 % water power + 0,4% conventional power plants) Prioritized electricity: - wind power 20% Electricity from turbines (results from scheme design, PSO 1999) - other Danish 26% Danish system electricity 1997 (Division between heat system electricity and electricity is undertaken by means of energy quality) Table 5.2: View of division of VWS A/S’ electricity consumption 2000.
5.1.3.2 Manufacturing of tower The towers for VWS A/S turbines are to some extent manufactured at VWS’ own factory in Varde, and the rest is purchased from sub-contractors. In this project only data from towers manufactured by VWS A/S has been used.
The towers are manufactured in steel. The steel is delivered to VWS A/S in steel plates, which have already been pre-cut in a way that VWS A/S’ factories do not need to cut up the plates any further. In addition, there is no waste of steel. When the iron plates arrive at VWS A/S, the plates to the tower sections are rolled. Every section is welded lengthwise, then the individual sections are welded together. The subsequent treatments i.e. sandblasting and surface treatment of the towers are not performed at VWS A/S, but at sub-contractors.
In this project the manufacturing at VWS A/S and the subsequent surface treatment at sub-contractors have been included.
The manufacturing of steel plates has been modelled as steel plates from the UMIP-database, yet in a slightly modified version based on information from the Danish Steel Rolling Mill, which has also been used in the scheme design.
The process, which has been found in the UMIP-data base for steel plates (89% primary), has been found not to be up-to-date and not to dispose of waste correctly. Oven slag is produced when manufacturing steel, and in the UMIP oven slag has been defined as hazardous waste. Actually, the oven slag is reused in the asphalt5 industry and the oven slag has not been defined as hazardous waste in accordance with the Ministry of The Environment’s Statutory Order no (Ann. No. 619 of 27/06/2000). Therefore a modified version of the steel process has been made, in which the oven slag has been defined as bulk waste in stead of as hazardous waste. A form of reusing the oven slag should have been included, but to simplify the data collection it has been included as bulk waste.
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Data regarding consumption of steel, welding wire, welding powder, paint and sand blasting originates from VWS A/S’ item lists and information from the sub-contractors.
5.1.3.3 Manufacturing of nacelle The nacelle consists of the nacelle cover, which includes generator, gear, main shaft, yaw system, flanges etc.
The individual part components are not manufactured by VWS A/S, but are purchased from sub- contractors, and then the final finishing (welding, metal cutting) and subsequent assembling take place at VWS A/S’ factories.
5.1.3.3.1 Gear According to the supplier the gear to a 2.0 MW turbine consists of cast iron, 7CrNiMoS6-steel and 31CrMoV9-steel, which constitute approx 95% of the material consumption for the gearbox.
The final 5% of the material consumption is used for bearings, which consist of steel alloys. There is no available information about the composition of these materials.
Since it has not been possible to get specified information about the 2 CrMo-steel types, data for stainless steel has been included instead. Stainless steel is the kind of steel which is most similar to the CrMo-steel and has already been entered into the UMIP. I.e. the gear is assumed to consist of 50% cast iron and 50% stainless steel.
The supplier has not stated the energy consumption for manufacturing the gear. Therefore the energy consumption has been estimated based on information from a previous LCA of turbines6 by up-scaling the energy consumption on the basis of the weight of the gear. Electric power generation in Europe has been used, as the gears are delivered by a supplier in Europe.
5.1.3.3.2 Generator According to the supplier, the generator consists of cast iron and various steel types such as steel plates and cobber.
The manufacturer has not informed about the energy consumption during the manufacturing process, and therefore the energy consumption has also here been scaled on the basis of the weight of the generator from a previous LCA for turbines6. Here is used European electricity too, as the generator is delivered from a European producer.
5.1.3.3.3 Nacelle cover The nacelle cover for a 2.0 MW wind turbine is manufactured of composite material. The Danish plastic industry has made an LCA-screening of various plastic materials including the manufacturing of cabins7. Information from this has been used in present project. 5.1.3.3.4 5.1.3.3.5 Main shaft The main shaft for the wind turbine is manufactured of CrMo-steel. As the gear, this high power steel has been estimated with stainless steel.
The energy consumption for the manufacturing process of the main shaft has not been available and therefore it has not been included.
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5.1.3.3.6 Electricity switchboard
The control system (approx 1,500 kg), which has been placed in the nacelle, consists of electricity switchboards. VWS A/S has provided information about the individual components’ weights, as well as the weight of the steel cabinets. It has not been possible to find LCA-data on all the electronic components. However, estimated average figures have been applied. Like this, a model of the consumption of the average electronic has been used based on a work report from the Danish Protection Agency about ‘Elucidation about environmental declaration of contents of consumer electronic – from knowledge to action’8. In this way the energy consumption for manufacturing of materials and assembling by VWS A/S have been included, but exclusive of manufacturing of part components at the sub- contractors.
5.1.3.3.7 Other parts in nacelle In addition to above mentioned components the nacelle also consists of the following components: • Yaw system. • Bearing house. • Main brackets. • Torque arms (at gear). • Hydraulic systems. • Cables.
All above parts are also represented in this life cycle assessment, as we have received data from VWS A/S about the individual part’s weight and materials.
5.1.3.4 Manufacturing of rotor The blades are produced at VWS A/S’ factory in Nakskov.
VWS A/S uses Prepreg, which is a glass fibre mat impregnated with epoxy resin. It has been difficult to obtain information from the manufacturer and supplier about the composition and the manufacturing of Prepreg.
From the supplier’s PrePreg safety data sheets it is assumed that Prepreg consists of approx 40% epoxy and 60% glass fibre.
In the data base for the LCA-tools SimaPro, data has been found on Epoxy. The data is based on data from The Association of Plastics Manufacturers in Europe -APME9
The data has been transferred to the UMIP. However, there is incomplete data or lacking data on certain materials in the UMIP-data base, and unfortunately the epoxy data is incomplete which gives rise to some uncertainty. Still, the available data and estimated time are regarded to be the best data possible. If the environmental impacts are calculated from epoxy in SimaPro with the UMIP-method and in UMIP, respectively, it is found that most of the impacts to some extent are similar, while as regard to bulk waste there are differences on human toxicity, corresponding to a factor of 50-200. Some of the differences are due to the different data basis in the 2 data bases, missing data in the UMIP-data base compared with the SimaPro data bases as well as differences in the calculation methods. Taking all this into consideration, it is still estimated that the epoxy data used in the present project is acceptable.
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The blades are primarily manufactured of PrePreg, which is uncured by using heat and vacuum. A blade is constructed over a spar/root joint, which is made of Prepreg. The blade shell, which consists of two
PrePreg pieces, is placed over the spar and glued together around the spar.
Prepreg is delivered to VWS A/S on rolls. The Prepreg rolls are covered with separation film. At VWS A/S the Prepreg is cut into appropriate pieces to the spar and the blade shell.
PUR-glue and other materials are used to assemble the blade shells and the spars. Sufficient LCA-data on PUR-glue has been impossible to obtain, but from the manufacturer’s environmental accounts it has been possible to procure some data, which is estimated to be relatively adequate. The environmental accounts do, however, cover several types of glue from the producer, for which reason only average data has been used in cases, where it has not been obvious to omit content substances such as solvents.
The spinner is also included in the rotor statement. Finished part components for the spinner are delivered to VWS A/S, who is in charge of the assembling. The spinner consists of nose cone supports, blade hub, torque arm plates, torque arm shafts and torque arm blocks. Furthermore, the spinner is constructed of fibre glass-reinforced polyester. VWS A/S has provided information about all components, material types and weights of these. The glass fibre has been modelled as described under the ‘Nacelle Cover’. CrNiMo-steel is equivalent to stainless steel.
Apart from the above mentioned, VWS A/S has informed that some auxiliary materials such as vacuum fleece and various plastic films are used.
5.1.3.4.1 Waste from the blade manufacturing process When using PrePreg in the manufacturing process up to 10% of the PrePreg turns into waste due to cut- offs. Previously, the waste was sent to incineration, but this no longer possible. In the future the waste will be reused or uncured and deposited. As both processes are very new, it has not been possible to include them in this environmental assessment.
VWS A/S disposes of separation film as combustible waste.
The auxiliary materials such as vacuum fleece, vacuum foil and slip and bleeding foil, will all be removed before assembling of the blades. The vacuum fleece has collected surplus epoxy, however, the extent of this is unknown. Auxiliary materials are disposed as combustible waste.
5.1.4 Manufacturing of onshore foundation The foundation for the onshore turbine consists of plate foundations made with reinforced concrete. Typically, the size is 15 × 15 metres and 2 metres deep. The foundation is concreted in situ. After excavation the hole is filled with approx 350 m3 concrete with approx 27 tons of reinforcement. Transport of concrete and reinforcement to the farm area has not been included. Only materials are included in the model.
5.1.5 Manufacturing of offshore foundation At the time of the data collection for this project no real practical experience was available in Denmark regarding establishment of steel foundations for offshore turbines. The following considerations are primarily referred to the tender documents for the foundation agreement at Horns Reef.
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It is presumed that the turbine is placed on 10-13 metres of water, calculated from sea surface to sea bottom at average water level. Like this, secure dimensioning has been chosen in proportion to the average water dept at Horns Reef at 6.5 – 13 metres.
The foundation consists of a foundation pile, a transition piece, boat landing platform, platform and cathode protection.
As the dimensions for the foundation pile may fluctuate due to various sea depths, different assumptions are made as regard the dimension of the foundation. The dimensions are as follows:
Foundation pile : High-strength steel Length : 29,700 mm Diameter : 4,000 mm Thickness : 30 mm, 45 mm, 50 mm
Dimensions for the transition piece are as follows: Length : 17,000 mm Diameter : 4,240 mm (bund), 4,000 mm (top) Thickness : 40 mm and 50 mm
5.1.5.1 Manufacturing of foundation piles and transition piece. The production of the foundation pile and the transition piece is based on above-mentioned tender materials. Furthermore, experience from previous LCA-studies on various processes as welding, sand blasting etc. and from manufacturing the turbine tower has been used.
The quantity of steel has been determined from the tender material. The energy consumption has been estimated from a previous LCA-study on turbines regarding production of tower. It has been assumed that the energy consumption is linear correlated to the steel tonnage. Furthermore, experience based on data from the LCA-study about material consumption for the welding process has been used. It has not been possible to determine other parameters for the manufacturing process of the pile. For the foundation, the following data has been used: steel, energy consumption, welding, acetylene, tetrene, atal-6, welding powder, oxygen and argon.
5.1.5.2 Surface treatment The steel is sand blasted, cf. tender material. Incoming quantities of sand has been stated. For the coating of the steel a 2-component thick film (epoxy) coating has been stated.
Regarding the paint data has been provided from the supplier’s green accounting, and this data has been attempted to be modelled in the UMIP. However, more incoming substances have been used, where it has been difficult to find data. Some data has been omitted, whereas the most important data has been found in e.g. SimaPro’s data base. It has not been possible to get information from the suppliers about the energy consumption and emissions obtained from the processes.
5.1.5.3 Assembling of foundation piles and transition piece The transition piece has a larger dimension than the foundation pile. A concrete based material with high-strength quality has been used for coupling the pile and the transition piece. However, it has not been possible to obtain data about the manufacturing of this special concrete material within the deadline of the project. Instead data on production of ordinary concrete has been used. Data refers to Aalborg Portland’s environmental statement of 199910.
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5.1.5.4 Boat landing platform and platform
Both the boat landing platform and the platform have are manufactured in steel and entered with quantities found during the projecting the foundation11.
5.1.5.5 Cathode protection In order to minimize corrosion the foundation pile has been cathode protected inside as well as outside. Passive solutions of cathode protection have been selected, which means that no applied power is needed for the protection. I.e. we use sacrificial anodes made of aluminium, where the sacrificial material must be sufficient to protect the pile in its lifetime.
In connection with the erection of offshore turbines at Horns Reef the dimension of the cathode protection (inside and outside) has been calculated. The quantity of material may vary depending on the water depth. A water depth of 10-13 metres has been estimated.
The lifetime of the cathode protection has been set to be 30 years. However, the lifetime has been recalculated to 20 years, which also applies for the rest of turbine. During the dismantling and scrapping 47% of Al will be unexploited and the part, which has been exploited will be included in the operation of the foundations. For the protection system, all incoming cables are included, e.g. the cobber in the cables. It has not been possible to include a complete material composition and/or the lifecycle of the cables. All cables are made of cobber and are included in the model as pure cobber.
5.1.6 Manufacturing of internal farm cables to offshore wind farm 32 kV PEX submarine cables are used as internal farm cables, i.e. between the turbines and between the turbine farms and the 32/150 kV transformers.
The 95 and 150 mm2 cables are manufactured by the Oslofjorden, and the 400 mm2 cable is manufactured in Hanover.
Data regarding the manufacturing of the cable has been obtained from the supplier’s data sheet for this cable. The cables contain cobber, lead, steel and insulator. The insulator is assumed to be polyethylene. All the materials are known in the UMIP data base.
During the manufacturing process we have estimated with 50 km onshore transport from the material supplier to the cable factory.
5.1.7 Manufacturing of transformer station to offshore wind farm The foundation for the platform, which has a 40-year lifetime, consists of three piles; two of these with a diameter of approx 1,6 m and a pile with a diameter of 2,3 m. The three foundation piles are mutually combined via lattice girders.
The platform has been placed approx 14 m above mean water level and holds a height of approx 7 m. The ground dimensions are 20 × 28 m. The steel superstructure will be covered on the sides to create shelter on the platform. On top of the platform – approx 23 m above mean water level – a helicopter platform has been placed with a diameter of approx 20 m.
The superstructure is assembled onshore and transported to the offshore wind farm as one module. The module is placed on the substructure by means of a floating crane.
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The foundation and the platform consist of steel, stainless steel, aluminium and reinforced concrete, and
UMIP-database has data on all these materials.
The transformer primarily consists of oil, tin, cobber and steel. LCA-data can be found in the UMIP regarding these materials.
5.1.8 Manufacturing of 150 kV PEX submarine-/onshore cable and SF6-system for offshore wind farm A 150 kV PEX cable with a 40-year lifetime is used for transferring electricity from the offshore transformer station to the connection of the power transmission grid via the cable transition station at Hvidbjerg Seashore south of Oksby. The length of the cable from the offshore transformer station to the cable transition station is approx 20 km; and from the transition station to the connection of the 150 kV transmission grid there is approx 34 km. In other words 20 km of the cables are submarine cables and the remaining 34 km are onshore cables.
The submarine cable starts at the transformer platform at the offshore wind farm and ends onshore by Hvidbjerg Seashore south of Oksby. On the coast the cable is pulled approx 1,000 metres onshore, and subsequently the submarine cable is connected to the onshore cable in a cable transition station. And there the onshore cable is wired to the 150 kV-transformer station on Karlsgårde north of Varde.
The cable transition station at Oksby connects the submarine cable from the offshore wind farm to the onshore cable. Apart from the transition between the two cable types, the transition station also contains a fixed coupled output coil for compensation of the cable’s generated reactive effect.
The cable transition station has been established as a capsular SF6-system in order to minimise the dimension of the site. The site has been placed in a building of approx 200 m2. This building is very simple and has not been included in this LCA, as it has been estimated to be insignificant. For the manufacturing of the cable transition station primarily cast iron, oil, cobber and steel has been used.
The submarine cable in the trace will be a 150 kV three-conductor, PEX cable equipped with a sea armouring of steel wires. The submarine cable primarily consists of lead, cobber, steel and plastic.
The onshore cable will be equipped with one-conductor PEX isolated cables with 1.200 mm2. Each of the three one-conductor cables weighs approx 9 kilos/m and has a diameter of 90 mm. The onshore cable is manufactured at one of the ABB Group’s cable factories in Karlskrona. The primary materials in the onshore cable are aluminium, cobber and plastic and also sand and concrete for the cable channel.
During the manufacturing process a 50 km onshore transportation has been estimated from the material supplier to the cable factory.
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5.2 Incoming materials
The largest quantities of incoming materials for the wind turbine and the transmission respectively
(including internal cables) are shown in Table 5.3.
Materials to offshore wind farm Materials to onshore wind farm Materials Offshore turbine Transmission Onshore turbine Transmission (kg/turbine) (kg/farm) (kg/turbine) (kg/farm) Steel 349.240 1.488.186 223.140 0 High- 13.331 8.000 13.328 0 strength steel (stainless steel) Cast iron 20.688 131.000 20.688 0 Glass fibre 21.842 0 21.507 0 Plastic 3.879 822.158 3.088 11.016 Lead 2 2.354.742 0 0 Cobber 2.958 858.237 2.816 2.032 Aluminium 3.545 364.450 1.678 576 Zinc 9.914 700 203 0 Concrete 0 1.375.000 805.000 0 Table 5.3: Significant incoming materials in above model of offshore- and onshore wind farm, respectively. Note that statement of materials to the turbines is stated per turbine, while the materials to the transmission system are stated for the total transmission system, i.e. per farm.
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6. Life cycle impact assessment The life cycle survey of offshore wind farms and onshore wind farms has been used to make a calculation of the environmental impacts for the two farms. The calculation has been made in the Danish LCA tool UMIP (see more specific description in section 1.1).
6.1 Environmental impacts The potential environmental impacts shown below have been included:
• Global warming. • Ozone-depletion. • Acidification. • Radioactive waste. • Nutrient enrichment(eutrophication). • Human toxicity. • Eco-toxicity. • Bulk waste. • Hazardous waste.
Global warming is the atmosphere’s ability to reflect a part of the heat radiation to the earth. The greenhouse effect is increased by the atmosphere’s content of carbon dioxin, CFC, laughing gas and methane among others. Increased emission of these substances might impact the heat balance of the earth and over the next years this may result in a warmer climate.
Ozone depletion: Formation and depletion of ozone are naturally in balance in the earth’s stratosphere 15-40 km up into the atmosphere. But the depletion will increase due to the humans’ emissions of halocarbons, i.e. organic compounds, which contain chlorine or bromine, and which is persistent enough to reach the stratosphere. The reduced amount of ozone in the stratosphere means that a more harmful UV-rays in the sunlight will reach the surface of the earth.
Acidification means that acids and compounds, which can be transformed into acids are emitted into the atmosphere and subsequently deposited in the water and soil environment, which means that the admission of hydrogen ions decline (pH decline), e.g. the degree of acidity will be increased. This will for example result in negative consequences for coniferous trees and fish by way of forest die-back and death of fish, and furthermore this will bring corrosion damages on buildings metals etc.
Radio active waste is waste of low radiation intensity from nuclear power plants, which are deposited at special deposits for radio active waste.
Nutrient enrichment is an impact on eco systems with substances, which especially contains nitrogen (N) or phosphorus (P). The consequence might be a disturbed biological balance, where a strong growth of e.g. plants in aquatic environment at the expense of other life forms in the aquatic environment.
Human toxicity: Some substances are not very biodegradable and can reach high concentrations which cause toxic effects on humans or on eco systems in various places in the environment.
Eco-toxicity: see human toxicity.
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Bulk waste is construction waste and similar waste, which are deposited at controlled waste deposits.
The waste is characterized by the fact that it does not contain environmentally hazardous substances.
Hazardous waste is waste, which must be brought to special processing plants such as Kommunekemi A/S or to a special deposit for hazardous waste. The waste is characterized by the fact that it contains environmentally hazardous substances, which may be released during the stay on the deposit.
For further descriptions we kindly refer to the documentation for the UMIP-method12.
The first 4 examples are typical impacts from non-renewable energy productions and therefore will be very dependent on the energy consumption which especially is included in the sub- contractor’s production. Radio active waste derives from nuclear power stations in countries such as Sweden, Germany and France.
6.2 Calculation method By means of the UMIP pc-tool a normalization of the environmental impacts has been made. I.e. the environmental impacts are stated in milli-person equivalents (mPE). The results reflect what 1 kWh power produced from the wind farms through their lifetime make up of an average citizen’s total impact12. This means that the environmental impacts of power from the farms are related to a standard citizen’s average contribution to the individual environmental impacts.
6.3 Results As a control of how large a share of the materials which have been included in the model compared to the stated weights in accordance to VWS A/S´ item list of the turbines and design drawings of foundations, the total quantities have been compared to the stated weights in below table 6.1.
Offshore turbine Onshore turbine General Model General Model specifications specifications Tower 140 t (60 m high) 150 t (100%) 165 t (78 m high) 168 t (98,5%) Nacelle 64 t 59 t (92%) 61 t 62 t (100%) Rotor 38 t 37 t (97%) 37 t 37 t (100%) Foundatio 203 t 227 t (100%) 832 t 832 t (100%) n Table 6.1: Statement of compliance with weight measurements.
Above table shows that nearly all materials have been included. However, some give over 100%, but there is a certain uncertainty of the stated figures of the components’ total weight.
6.3.1 Statement of resource consumption The life cycle mapping can be added up in a statement of resource consumption for the total lifetime of the turbine.
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Horns Reef offshore wind farm Tjæreborg onshore wind farm
Quantity Quantity Resource Resource [g/kWh] [g/kWh] Dammed water 516 Dammed water 391 Water 70 Water 72 Crude oil, fuel 1,17 Stone, broken granite 3,39 Pit coal, fuel 0,75 Crude oil, fuel 1,25 Crude oil, raw material 0,46 Ca (calcium) 1,00 Natural gas, fuel 0,39 Pit coal, fuel 0,69 Fe(Iron) 0,41 Natural gas, fuel 0,30 Brown coal, fuel 0,22 Brown coal, fuel 0,22 Calcium carbonate 0,18 Fe(iron) 0,21 (CaCO3) Aluminium (Al) 0,02 Calcium carbonate 0,15 (CaCO3) Zinc (Zn) 0,008 Aluminium (Al) 0,15 Lead (Pb) 0,007 Pit coal, raw, raw 0,09 material Pit coal, raw, raw material 0,006 Zinc (Zn) 0,004 Cobber (Cu) 0,004 Cobber (Cu) 0,002 Table 6.2: Significant resource consumption of 1 kWh electricity from offshore- and onshore wind farm, respectively.
For both the offshore wind farm and the onshore wind farm the largest resource consumption is dammed water, which is used for the electric power generation on hydroelectric power stations, which primarily are used in Norway. The 516 g dammed water/kWh for the offshore wind farm corresponds to 0.0013 kWh electricity, while the 391 g for the onshore wind farm corresponds to 0.001 kWh electricity.
Apart from dammed water, other water is the second most used resource. This water is used in several production processes by the sub-contractors and at material production.
Oil, pit coal, natural gas and brown coal are all used for the energy production. Stone in the form of broken granite and calcium enter in large quantities for the onshore wind farm, which is due to the large consumption of concrete for the foundation and for the cable channels. Crude oil – raw material, which is used for the offshore wind farm, is used as transformer oil, among others, and is entered in quite large quantities.
Iron is also one of the most used resources; and this material is used to produce steel, which is applied in large quantities on the wind farms.
Calcium carbonate derives from fuel for transport.
At the offshore wind farm aluminium is primarily used for the foundation to the transformer station, in the cable transition station and to the submarine cable. Lead and cobber are primarily used for the submarine cable, and further lead derives from the consumption of Danish electricity.
At the onshore wind farm aluminium and cobber are primarily used in cables and nacelle.
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6.3.2 Environmental impacts of 1 kWh
The main result of this LCA is the environmental impacts of 1 kWh electricity from offshore wind farms and onshore wind farms, respectively. These are classified in below Figure 6.1.
Comparison of the most significant environmental impacts of 1 kWh electricity from Horns Rev offshore wind farm and Tjæreborg onshore turbine farm
Radioactive waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone-depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-person equivalents, mPE/kWh
Horns Rev wind farm Tjæreborg onshore turbine farm Figure 6.1: Environmental profiles of 1 kWh electricity from offshore wind farms and onshore wind farms.
Figure 6.1 shows that the environmental profile of 1 kWh from Tjæreborg onshore wind farm and Horns Reef offshore wind farm, respectively, is relatively identical, however, except hazardous waste, where the impact is significantly larger (approx 100%) for the offshore wind farm than for the onshore wind farm.
The largest differences derive from bulk waste, hazardous waste, radio active waste, eco-toxicity and greenhouse effect, where the impacts from offshore wind farms are larger. This is due to the fact that after removal of the offshore wind farms a great part of the foundation is left behind, as only 1 metre below the seabed will be removed, which means that 26% (weight) of the mono pile is left in the seabed. In addition, more metals such as cobber and lead in the cables are used in the offshore wind farm than in the onshore wind farm
The Global warming effect derives primarily from the production of energy, which is used during the manufacturing of materials and assembling of turbines. The radio active waste also derives from the energy production in the countries, where they use nuclear power such as Sweden and Germany. Swedish electricity is part of the manufacturing of the cables to the offshore wind farm, while German electricity is part of the European el-mix which is used for several processes in steel manufacturing.
Hazardous waste basically only derives from the manufacturing process, and first and foremost from the manufacturing process of materials for the internal cables at Horns Reef winds farm and materials for the nacelle. Bulk waste highly derives from the steel manufacturing and from disposal of the blades, which
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6.3.3 Environmental impacts divided on life stages. A division of environmental impacts on life stages can be seen from the following figure, in which both onshore wind farm and also offshore wind farm are presented.
On the figure both a positive and a negative scale can be read This means that the dismantling and removal show a negative result, and this must be deducted from the positive column, and by that you obtain the final environmental impact (as seen in Figure 6.1.). The reason why dismantling and removal give cause for negative impacts is that recycling is used to a high degree, which means that you are credited the quantity of materials, which are recycled. Included in dismantling and removal is energy consumption of dismantling, transport/preparation of materials ready for new use.
Environmental impacts of 1 kWh from Tjæreborg onshore turbine farm divided on stages
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment M
Acidification
Ozone-depletion
Global warming
-0,0040 -0,0030 -0,0020 -0,0010 0,0000 0,0010 0,0020 0,0030 0,0040 0,0050 milli-person equivalents, mPE/kWh
Manufacturing Operation Transport Dismantling
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Environmental impacts of 1 kWh from Horns Rev offshore wind farm divided on stages
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone-depletion
Greenhouse effect
-0,0040 -0,0030 -0,0020 -0,0010 0,0000 0,0010 0,0020 0,0030 0,0040 0,0050 milli-person equivalents, mPE/kWh
Manufacturing Operation Transport Dismantling Figure 6.2: 1 kWh electricity from onshore wind farms and offshore wind farms, respectively, divided on life stages.
Not surprising, the manufacturing stage is crucial for the environmental impacts for electricity from turbines, both for offshore wind farms as well as for onshore wind farms. At the same time it is important to conclude that disposal of materials is terribly important for the environmental profile on electricity generated from wind farms. If a less extent of recycling is assumed, this will immediately be shown on the environmental impacts.
6.3.4 Environmental impacts divided on components A division of the environmental impacts based on components is presented for 1 kWh electricity from the onshore wind farms and the offshore wind farms, respectively, in Figure 6.3.
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Environmental impacts of 1 kWh from Horns Rev offshore wind farm divided on turbines and transmission
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human toxicity
Nutrient enrichment
Acidification
Ozone-depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-person equivalents mPE/kWh
Offshore turbines The transmission grid
Environmental impacts of 1 kWh from Tjæreborg onshore turbine farm divided on turbine and 10kV cable
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0001 0,0002 0,0003 0,0004 0,0005 0,0006 0,0007 0,0008 0,0009 0,0010 milli-person equivalents, mPE/kWh
Turbine 10 kV cables to transformer
Figure 6.3: Environmental impacts for 1 kWh electricity from respectively onshore wind farms and offshore wind farms allocated on turbines and transmission.
Figure 6.3 shows that the transmission on the offshore wind farm composes approx 10% of the environmental impacts. The transmission on the onshore wind farm is basically insignificant. At the onshore wind farm, only 8 km cables are used for the transmission grid, whereas, at Horns Reef the transformer station is constructed and approx 50 km cables are used for transmission.
By dividing on main components it appears that there are some differences in the offshore wind farms and the onshore wind farm. Regarding the onshore wind farm it is primarily the nacelle, the blades and the tower which contribute to the total environmental impacts. Regarding the offshore wind farm it is
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6.3.5 Comparison with Danish electricity ’97 In order to relate the environmental impacts to the average Danish electricity production we have decided to compare 1kWh electricity from Horns Reef and Tjæreborg, respectively, with average Danish electricity ’97 prepared by the energy societies in 20006.
Comparison of the environmental impacts of 1 kWh from Horns Rev offshore wind farm, Tjæreborg onshore turbine farm & Danish el 97
Radio active waste
Hazardous waste 0,0 Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification Ozone depletion 0,09 Global warmi ng
0,00 0,01 0,01 0,02 0,02 0,03 0,03 0,04 0,04 milli-pers on equivalents , mP E /kWh
Horns R ev offshore wind farm Tjæreborg onshore turbine farm Danis h el ´97
Figure 6.4: Comparison of 1 kWh electricity from Horns Reef and Tjæreborg with average Danish electricity ’976 respectively.
Please note the differences in the functional unit for the two assessments. Regarding Danish electricity ´97 the functional unit is 1 kWh electricity delivered at the consumer, whereas for turbine electricity it is 1 kWh electricity delivered to the electricity grid. This means that in the statement for Danish electricity the total electrical grid has been included, but this is not the case in the statement for Tjæreborg and Horns Reef wind farm where it has not been included.
As the above figure shows, the environmental impacts from turbine electricity from Tjæreborg and Horns Reef, respectively, is considerably lower than from Danish average electricity in 1997.
6.4 Interpretation of results The data quality which has been used in the present LCA has been estimated to be satisfactory for the purpose, despite some lacks and assumptions. However, we estimate that for the most significant areas the data has been found valid. One of the objectives with this LCA has been to use LCA as a basis for improvement strategies internally in VWS A/S, and not use these results for publishing and comparison with other turbine producers.
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6.4.1 Improvement strategies
One way of using the results of a LCA in the internal product development and product improvement is to make a list with pros and cons. I.e. from the LCA results it should be possible to assess the materials and/or the substances, which result in the largest environmental impacts, and in this way it should be attempted to replace or minimise these in future products.
In this project it has not been possible to provide alternatives for the most damaging substances/materials, as this would require thorough examinations of the alternative materials, both regarding the physical qualities and the environmental qualities as well as the financial consequences.
The objective has been to prepare improvement strategies for the manufacturing, the operation and the disposal stages, respectively.
6.4.1.1 Manufacturing For the manufacturing of the turbines the objective has been to prepare alternatives to the present production, either in the form of other materials or other processes. By using the life cycle assessment it has been found that especially high-strength steel and Prepreg cause the environmental impacts. In other words, these two materials should be focused on in connection with material substitution or other improvement strategies.
It might be relevant to look at ‘an improvement strategy’, which has already been implemented due to technical reasons, concerning Prepreg. The alteration is to change the method of production regarding root joints in a way that liquid winding is used rather than Prepreg, which is used at present. Liquid winding means that the dry glass fibre mats are required and epoxy resin is applied at the wrapping process. When using Prepreg the mats have already been pre-impregnated with epoxy. A smaller waste of epoxy and glass mats could be the environmental advantage by using liquid winding and result in smaller quantities of waste and possibly reduce the impact on the working environment.
As it has actually been impossible to get sufficiently detailed LCA-data and data for different processes, the comparison would be impossible to make. In order to see the differences and obtain a reliable result, quite precise data on materials and processes must be available.
6.4.1.1.1 Type of foundation As stated previously the offshore foundations do not give a significant contribution to the total environmental impacts. We have tried to establish the significance the various types of offshore foundations have to the environmental impacts. Three types of foundations have been evaluated and are presented in Figure 3.2. Even though not all three types would technically be appropriate for Horns Reef, the assessment can still be used to show the extent of the environmental impacts the individual foundation would have by choosing another foundation. Like that, these can be used as design parameters on future projecting of wind turbine farms.
When calculating the environmental impacts for the 3 foundations it was assumed that the transition piece, the boat platform, the transport and the operation are identical on all three foundation types.
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The following data has been entered in the calculation to be used for the comparison:
Materials Quantity Kg Precondition Mono pile Steel 130.000 Approx 10 m foundation is rammed Cathode, Al 700 down into the seabed. This unit remains on the seabed, the rest is reused After 20 years 47% Al is unused. Tripod Steel 102.000 Approx 10 m foundation is rammed Cathode, Al 700 down into the seabed. This unit remains on the seabed, the rest is reused. After 20 years 47% Al is unused. Cassion Steel 110.000 The entire foundation will be removed – Concrete x steel will be reused. Concrete is not Cathode, Al 700 included in the model due to lack of data. After 20 years 47% Al is unused. Table 6.3: Data, which has been entered in the calculations for comparison of environmental impacts of the three foundation types.
Comparison of environmental impacts of various foundation types for Horns Rev offshore wind farm
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-personequivalents, mPE/kWh
Mono pile Tripod Cassion
Figure 6.5: Comparison of the environmental impacts for 3 various foundation types at Horns Reef wind farm.
When making an environmental comparison of the 3 foundation types it is obvious that there are some minor differences on hazardous waste and bulk waste. This is due to differences in quantity of material, which is left behind on the seabed when removing the foundations. The largest quantity of material is left behind by the mono pile, whereas the cassion foundation is removed completely.
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6.4.1.2 Operation
There has been some uncertainty about whether inspections and scheduled/unscheduled service visits of the offshore wind farm at Horns Reef should take place by helicopter or by boat, but we expect to perform both by helicopter and by boat. In general, we have found that inspections and scheduled/unscheduled service visits do not have significance for the total environmental impacts for the offshore wind farm, but we estimate they amount to approx 10% of the environmental impacts, see Figure 6.6. Various transport scenarios have been calculated in order to assess the environmental differences when using boat and helicopter for transport in connection with inspections and scheduled/unscheduled service visits,
• The actual, with 1 time boat and 4 times helicopter/year. • 100% helicopter • 100% boat
Environmental impacts per kWh for Horns Rev offshore wind farm with operation visualized separately
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-person equivalents, mPE/kWh
Horns Rev-wind farm Operation related
Figure 6.6: The environmental impacts for Horns Reef wind farm per kWh, where the operation stage is shown as separate life stage
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Comparison of environmental impacts of various transport scenarios at servicing at Horns Rev offshore wind farm
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Oz on e depl et i on
Gl obal war mi ng
0,000000 0,000005 0,000010 0,000015 0,000020 0,000025 0,000030 0,000035
milli-person equivalents, mPE/kWh
100% helicopter Cur r ent 10 0 % boat s
Figure 6.7: The environmental impacts for various scenarios for transport in connection with operation of the offshore wind farm at Horns Reef.
Figure 6.7 shows that the 3 scenarios for transport indicate considerable differences in the environmental impacts. The use of boat has very little environmental impacts, in fact so little that it is not visible on Figure 6.7, whereas the use of helicopter has significantly larger environmental impacts, but still insignificantly small impacts compared with the other life stages.
6.4.1.3 Disposal and recycling A workshop has been held about the disposal stage, where various strategies and problems about disposal of various materials were discussed. From this workshop the most significant conclusion was that it is important too keep the materials separated during the manufacturing process. In this way it is possible to maximise the recycling level of the materials. In the product development stage it is important to consider the environmental impacts, the materials will have when they are disposed. However, there was no exact recommendation of materials at the workshop.
6.4.1.3.1 Blades The blades are assumed to be delivered to a waste disposal site simply because no recycling methods are available today. This means that the blades represent a large contribution to the environmental impact ‘bulk waste’ (26.1% for Tjæreborg and 17.4% for Horns Reef). We are continuously working on developing suitable methods for recycling of turbine blades. Combustion of blades has been discussed as a possible solution, and here the individual materials will be separated out as waste products. However, this method is uncertain, as we do not know to what extent the materials can be used for the same purpose or it must be earmarked for some other use.
In order to estimate the importance of depositing blades we have made calculations of 3 various scenarios on how to dispose of blades:
• The present with 100% depositing of blades.
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• Combustion of blades without the possibility of recycling the materials.
• 90% recycling of the materials, exclusive of processing and 10% of the materials to deposit.
The calculations have been made for the total lifetime of the blades and assessed for 1 kWh, i.e. inclusive of manufacturing, transport, dismantling and disposal. This calculation has been made at Tjæreborg onshore wind farm, but the differences between the 3 scenarios are identical on the two farms, as they have identical turbine types and blades.
Comparison of environmental impacts at various removal scenarios of blades for Vestas V-80 2,0MW turbine
Radio active waste Hazardous waste
Volume waste Eco-toxicity Human Toxicity
Nutrient salt load Acidification
Ozone depletion Global warming
0,00000 0,00005 0,00010 0,00015 0,00020 0,00025 milli-person equivalents, mPE/kWh
Blades - Volume waste Blades - Combustion Blades - Recycled 90% Fi gure 6.8: Environmental impacts on various scenarios for disposal of blades.
Comparing the 3 disposal scenarios shows that there are only minor differences on the environmental impacts, apart from the category ‘bulk waste’. Bulk waste does, of course, generate very large impacts, when the blades are deposited. Combustion of blades also generates a very large quantity of bulk waste, as the glass fibre in the blades is inflammable and therefore ends as a residual product from the combustion procedure. This residual product is defined as bulk waste.
6.5 Energy balance One of the most significant aspects in the assessment of energy sites is the product’s energy balance. The energy balance is an assessment of the relation between the energy consumption of the product and the energy production throughout the lifetime.
6.5.1 Energy consumption From the resource statement of the wind farm’s lifecycle, the energy consumption per turbine including grid connection has been calculated i.e. manufacturing, operation, transport, dismantling/disposal and transmission. In the statement, all energy resources have been included for the entire wind farm’s life cycle. These quantities are recalculated by means of calorific value to energy. The energy has been stated as gross energy, i.e. the energy which has been added in the form of fuel to a site has been included, and not the produced energy.
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6.5.1.1.1 Offshore wind farm
The calculations of the energy consumption, by means of LCA, for Horns Reef wind farm has been shown in Table 6.4. The calculations show that the energy consumption per offshore turbine is 6.074.655 kWh, and from section 3.1 it is known that one turbine delivers 8.088.000 kWh/year.
Energy consumption [kJ/kWh] Manufacturing/dis mantling Operation Transport Total Fossil fuel Coal 26,48 1,58 0,003 28,07 Oil 42,33 8,15 1,09 51,56 Gas 17,51 1,18 0,07 18,77 Brown coal 3,59 0,41 1,45E-07 4,00 Renewable energy Water 25,93 0,96 0,002 26,89 Straw 8,28E-04 4,51E-08 0 8,28E-04 Wood 1,28E-06 1,98E-08 0 1,30E-06 Other biomass 0,58 0,03 7,52E-08 0,62 Nuclear power 4,90 0,38 7,29E-05 5,28 Wind power 3,60E-03 0 0 0,0036 Total (kJ/kWh) 121,33 12,69 1,17 135,19 2.053.516.00 Total (kJ/turbine) 19.626.195.279 4 189.050.162 21.868.761.445 Total (kWh/turbine) in the lifetime 5.451.721 570.421 52.514 6.074.655 Table 6.4: The energy consumption stated for Horns Reef wind farm divided on life stages.
6.5.1.1.2 Onshore wind farm The calculation of the energy consumption, by means of LCA, for Tjæreborg wind farm has been shown in Table 6.5. The calculations show that the energy consumption per onshore turbine is 3.635.850 kWh, and from section 4.1 it is known that one turbine delivers 5.634.000 kWh/year.
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Energy consumption [kJ/kWh]
Manufacturing/dis mantling Operation Transport Total Fossil fuel Coal 18,11 1,55 0,00 19,66 Oil 46,56 6,45 0,56 53,57 Gas 13,33 0,99 0,04 14,35 Brown coal 3,48 0,47 2,25E-08 3,96 Renewal energy Water 19,51 0,78 0,00 20,29 Straw 7,00E-07 0,00E+00 0 7,00E-07 Wood 5,81E-07 0,00E+00 0 5,81E-07 Other bio mass 4,80E-01 3,40E-02 4,03E-08 0,51 Nuclear power 3,08 0,40 3,72E-05 3,49 Wind power 0,33 0,33 Total (kJ/kWh) 104,88 10,69 0,60 116,16 1.203.992.76 Total (kJ/turbine) 11.817.806.148 1 67.261.641 13.089.060.549 Total (kWh/turbine) in the lifetime 3.282.723 334.442 18.684 3.635.850 Table 6.5: The energy consumption is stated for Tjæreborg onshore wind farm divided on life stages.
6.5.2 Energy balance The energy balance has been calculated as the relation between the turbine’s energy consumption for manufacturing, operation, transport, dismantling, disposal and the expected average energy production.
Energy balance for the Horns Reef-turbine: 6.074.656[]kWh/turbine = 0.75years ≈ 9.0months 8.088.000[]kWh / turbine.year
Energy balance for the Tjæreborg-turbine: 3.635.850[]kWh/turbine = 0.65years ≈ 7.7months 5.634.000[]kWh / turbine⋅ year
From the above calculation it can be seen that the energy balance for the Horns Reef turbine is approx 1.3 months longer than for the Tjæreborg turbine. This difference is due to the significantly larger transmission grid, and the larger steel consumption for the foundations.
Appendix 3 shows a statement based on the principles in previously effected energy balances made by the Danish Wind Industry Associations. These calculations have been made based on input-/output tables and energy multipliers and it has been estimated which payback period Horns Reef and Tjæreborg
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Associations
6.6 Environmental Product Declaration This Environmental Product Declaration has been based on the common Northern NIMBUS method. The original environmental declaration of contents for offshore and onshore wind farms, respectively, see appendix 2.
The NIMBUS project is an abbreviation of ’Nordic project on Implementation of Environmental product Declarations type III in the Business Sector’. The project is a co-operation between the Confederation of Danish Industries (DI), Föreningen Svenskt Näringsliv and Næringslivets Hovedorganisasjon (NHO) of Norway. The project was carried out in the autumn 1999.
The purpose of the NIMBUS project was to promote more environmentally effective products and service performance in the Northern industries via implementation, testing and further development of a common Northern system for the Environmental Product Declaration based on ISO 14040-43 standards.
The conclusion of the NIMBUS project is based on efforts from representatives at some companies (case companies), the northern industry, experts within LCA and Environment Product Declaration and the steering group of the project. The development of a coordinated northern method shall strengthen the development and competition based on environmentally effective products. This objective should be met through an improved accessibility to environmental data for the suppliers.
Environmental Product declaration – type III may, in a purchase situation, be used to compare products from various companies. Not one single product is environmentally sound. It is only possible to find a product which is more environmentally sound or has less environmental impacts. Environmental Product Declaration – type III can also be used as an internal environmental assessment of a specific product, e.g. what can be done better? And/or how is it placed compared with the competitor’s product.
Environmental Product Declaration – type III methodology must fulfil the minimum requirements, which are stated in ISO 14040-43 series regarding communication with external parties. This means, to provide information to the consumers about a product’s content and make it easier for the consumers to choose and select environmentally sound products compared with the information from the environmental product declaration of product.
Therefore, environmental declarations of contents must be worded in a way, so ordinary consumers are able to read and comprehend them; i.e. they must be user-friendly.
The LCA-results show that the most important components, which are described in this Environmental Product Declaration, are:
• The most important resource materials. • Energy consumption. • Emissions. • Environmental impacts and their most important sources. • Disposal processes.
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6.6.1 Environmental Product Declaration –Methodological requirements in the Nordic region
The Nordic methodology for environmental product declaration is based on ISO 14025 technical guidance. The methodology must be as summarized and as general as possible. An environmental product declaration should make it possible to compare two products with the same functional unit in an easy and just way.
Environmental product declaration – type III shall be based on the LCA-methodology, where the LCA shall be implemented according to ISO 14040-43 standards. In the environmental product declaration methodology and presentation of data, it is important to separate the various stages of the product, i.e. production stage, operation stage, disposal stage. The reason for the separation into life stages is the higher uncertainties which are related to the operation stage and the disposal stage.
It is also important to define the product’s system delimitations, i.e. to define what’s included in an LCA. General regulations to define system limits are described in ISO 14040, and these regulations shall also be used in connection with the environmental product declaration. Some of the most important elements in the system are:
6.6.1.1.1 Geographical impact • Separation from other cognate product systems. • Which stages of the total lifetime have been included in the LCA, and these must be described clearly in the product’s process tree diagram • Which cutting-off rules have been used for the data collection?
Of other significant components in the environmental product declaration – type III are functional unit and allocation factor. The functional unit is decisive for using the environmental declaration of contents in order to compare, as described in ISO 14040. The allocation factor has significant impact on the results of the environmental product declaration. The general principles of the allocation factor have been described in ISO 14041 and must be followed in every environmental product declaration.
6.6.2 Data quality for V80-offshore wind farm Environmental Product Declaration The data quality of this product is based on ISO 14041 and used as a general guidance for this environmental product declaration. The objective for data quality in this LCA-project, which the environmental product declaration is based on, has been to use producer data.
In this way, more than 95% of the data used in the life cycle assessment of both turbine types and the transmission grid, i.e. materials and energy have been collected from relevant sources, e.g. VWS A/S and suppliers. And where it has been difficult to find more precise data, or data no longer is available, estimated values have been used (e.g. scaling of energy consumption for manufacturing of gear and generator). The age of the data has also been given high priority.
6.6.3 Environmental impact categories used in this Environmental Product Declaration In this Environmental Product Declaration the following 10 impact categories have been used. Of this, the first 6 are the basis for environmental product declaration, which have been carried out according to the NIMBUS principle:
• Global warming. • Ozone depletion.
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• Acidification.
• Photochemical ozone. • Nutrient enrichment. • Hazardous waste. • Human toxicity. • Eco-toxicity. • Bulk waste. • Radio active waste.
The following materials and energy have also been quantified in this environmental product declaration:
• Energy resources. • Material resources.
6.6.4 LCA-method and system delimitation In this environmental product declaration the functional unit has been set to 1 kWh electricity delivered from the wind farms. For the modelling, an Environmental Protection Agency’s pc-tool based on the UMIP-method has been used. The system, which has been included in this life cycle assessment, is foundation, tower, nacelle and blades and also transmission grid for onshore wind farm and offshore wind farm, respectively, including grid loss (see section 3.3. and 4.3.).
Materials and energy for the statement and the environmental impacts have been divided into life stages. I.e. production/dismantling, operation and transport stage.
Waste handling, after ended lifetime of 20 years, is based on the following assumption:
Materials Scenario Steel blades 90% reuse Stainless steel 90% reuse Cast iron 90% reuse Cobber 95% reuse Aluminium 90% reuse Plastic, PVC 100% deposit Glass fibre 100% deposit Oil 100% incineration Lead 90% reuse Zinc 90% reuse
More important elements for turbines, which have not or been included or which cannot be included in this, are the visual impacts on flora and fauna. These factors cannot be measured, but an assessment will be made of the environmental impacts (VVM) for turbine projects in connection with their approval. For Tjæreborg and Horns Reef VVM reports have been prepared13, 14 and subsequently approved.
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7. Sensitivity assessment The most significant assumptions for the two turbine farms are the energy production and the lifetime, as they clearly show on the environmental impacts for 1 kWh. The production at Horns Reef is fairly high, as the location is very good compared with the wind velocities. At Tjæreborg onshore wind farm the production is also high compared with the typical onshore sited turbines, as the Tjæreborg farm is sited just approx 500 metres from the Jutland west coast.
7.1 Energy production Figure 7.1 - here the results for bulk waste and greenhouse effect are shown as function of the energy production. By that, it is possible to see the variation of the environmental impacts within the normal production frames for the wind farms.
Bulk waste and greenhouse effect have been singled out to be looked at, because these 2 groups represent the materials/reuse and energy consumption, respectively, which are of most importance for the environmental impacts.
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B ulk waste at various productions at Horns R ev offshore wind farm and T jæreborg onshore turbine farm
0,005 0,004
0,004 0,003 0,003 0,002 0,002 0,001 0,001 On s hor e t ur bi ne f ar m Offshore wind farm pr oduct i on ar ea pr odduct i on ar ea 0,000 1.000 3.000 5.000 7.000 9.000 11.000 13.000
P r oduct ion ( MWh)
Offshore wind farm Ons hor e t ur bi ne f ar m
Global warming at various productions at Horns Rev offshore wind farm & Tjæreborg onshore turbine farm
0,004
0,004
0,003
0,003
0,002
0,002
0,001 Onshore turbine farm Offshore wind Globalwarming effect (mPE/kWh) 0,001 production area farm produtions area 0,000 1.000 3.000 5.000 7.000 9.000 11.000 13.000 Production (MWh)
Offshore wind farm Onshore turbine farm
Figure 7.1: The model’s sensitivity towards energy production, for respectively bulk waste and greenhouse effect. The annual production at Horns Reefs is 8.088 MWh and at Tjæreborg onshore wind farm 5.634 MWh. Besides electric power generation everything else is kept invariable. .
The calculation shows how the location of the wind farms and with this the production is important for the environmental impacts stated per kWh. The calculation presumes that all factors, except the electric power generation, are equal, i.e. no considerations have been made to for instance a better wind location,
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Experience show that an onshore wind farm’s (Tjæreborg) annual production area lies between approx 2,600 MWh/turbine and 5,600 MWh/turbine. Like this, an offshore wind farm’s (Horns Reef) annual production lies between approx 6.500 MWh/turbine and 9.000 MWh/turbine, depending on the siting of the wind farms both onshore and offshore. Therefore you can see that both Horns Reef offshore wind farm and Tjæreborg onshore wind farm have both been sited on one of the best locations.
In return Figure 7.1 also shows that the worst offshore location is environmentally better than an average onshore wind farm for both impacts.
7.2 Energy consumption Throughout the project it has been difficult to obtain energy consumption data from the sub-contractors. One of the processes with lack of energy consumption data is the casting of cast iron items. As there is a relative large consumption of casted items in the wind farms, corresponding to approx 26% of the weight of the nacelle and approx11% of the weight of the blades, assessment of how large impact energy consumption to this would have on the energy balance for the farms is performed.
For Horns Reef wind farm, the energy consumption for casting items has been assessed to be 40.000kWh/turbine and for Tjæreborg wind farm it has been assessed to approx 37.000 kWh/turbine. These energy consumptions have been recalculated to gross energy, as stated in the energy balance (see 6.5.1), and a new energy balance for the two wind farms will be computed.
The energy balance including the energy consumption for the casting of cast iron items will be: Horns Reef approx 9.2 months Tjæreborg approx 7.9 months
This amounts to an increase of approx 2% and 3%, respectively in relation to the energy balance without including the energy consumption for the casting.
So the assessment is that the energy consumption for the casting process is not decisive for the result of energy balance and life cycle assessment in full.
7.3 Location If you imagine similar wind farms erected on other locations, the conditions on some areas would be very different from the conditions at Horns Reef and Tjæreborg. In Denmark, the onshore sited farms will only be sited at a short distance from the existing electricity grid (at Tjæreborg only 8 km cable has been used), whereas this is not the case in other countries. In order to illustrate the importance of this factor on the LCA-model, the result of Tjæreborg wind farm has been compared with a calculation where it has been assumed that the turbines have been placed further apart from the electricity grid, and therefore 30 km cabelling is required, see Figure 7.2. In below calculation the electricity production has been assumed to remain the same.
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Environmental impacts of 1 kWh fra Tjæreborg onshore turbine farm compared with a similar farm with 30 km cable connection
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0001 0,0002 0,0003 0,0004 0,0005 0,0006 0,0007 0,0008 0,0009 0,0010 milli-person equivalents, mPE/kWh
Tjæreborg onshore turbine farm Tjæreborg onshore turbine with 30 km cable
Figure 7.2: Comparison of environmental impacts of onshore sited wind farm with various distances to the electrical grid.
The above Figure 7.2 shows that the cables only have a little impact on the total environmental impacts for the onshore wind farm. As Figure 7.1 shows, it is more decisive how big the energy production is on the onshore wind farm.
If you assume an offshore wind farm similar to Horns Reef wind farm sited somewhere else and with another distance to shore, there will be another loss in the cables, and presumable another depth.
In the following, a farm similar to Horns Reef wind farm has been assumed sited with double the distance and half the distance, respectively, from the shore as Horns Reef wind farm. A simple assumption is that the net-loss is linear with the length of cables, so the net-loss is doubled, when the distance is doubled, as the major part of the net-loss takes place in the cables. Further, a change of the foundation has been included. A very simple assumption has been made about the foundation, as its weight has been assumed to change ±20% at respectively a doubling and a halving of the distance. The following scenarios have been calculated:
• The actual location at Horns Reef. • Double distance to shore, double net-loss and 20% increase of foundation. • Half distance to shore, half net-loss, 20% decrease of foundation.
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Location of offshore wind farm
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-person equivalents, mPE/kWh
Near to edge location Current scenarios Near to coast location
Figure 7.3: The importance of the location for the offshore farm as concerns the environmental impacts. Under the very simple assumptions regarding the changes which take place in connection with alternative locations of a wind farm such as Horns Reef, it has been found that there is some impact of the location, but not significant changes. Again, it has been concluded that the energy production is one of the most significant parameters for the environmental impacts from the offshore wind farm during its lifetime.
7.4 Lifetime The lifetime of the total farm will have an impact ont he result proportionally. In the figure below, a 30- year-lifetime has been calculated for offshore turbines, as the offshore wind turbines can technically operate for up to 30 years, as they are worn less than turbines onshore.
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Environmental impacts by various lifetimes for onshore turbine farm and offshore wind farm
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depleti on
Global warmi ng
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 mili-pers on equivalents , mP E
Tjæreborg-20years Tjæreborg-30years Horns Rev-20years Horns Rev-30years
Figure 7.4: The lifetime’s influence on the environmental impacts.
In both cases, for Horns Reef, a lifetime of forty years has been calculated for the transmission part. In Figure 7.5 the impact of the assumption has been shown regarding a forty-year-lifetime for the transmission part.
It shows that the total lifetime of the two wind farms is decisive for the environmental impacts for 1 kWh electricity generated from the farms. Figure 7.4 shows that the lifetime is just as important as the production on the farms, as both give direct linear impact of the environmental impacts, made up per kWh produced in the farms. At a lifetime of thirty years for the offshore turbines, the environmental impacts are decreased approx 30% compared with the twenty-year-lifetime of the turbines.
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Environmental impacts of Horns Reef offshore wind farm with 20 and 40 year’s lifetime for the transmissions unit
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-person equivalents, mPE/kWh
20 years trans.lifetime 40 years trans. lifetime
Figure 7.5: The importance of various lifetimes for the transmission part to Horns Reef wind farm.
The lifetime of the transmission part to Horns Reef is less important for the total environmental profile for 1 kWh electricity from the offshore wind farm at Horns Reef.
7.5 Recycling The selected scenario of recycling of materials has proved to be important to the total environmental impacts, as it has been found that the used materials are decisive for the environment profile regarding electricity from the wind farms. Without the reutilization scenario, the environmental impacts would be up to 6 times as high.
As large quantities of metals are used at the wind farms, and especially at Horns Reef wind farm, due to the steel foundations and a large transmission grid, a sensitivity assessment has been prepared regarding the recycling of metals at Horns Reef wind farm.
At the workshop about dismantling and disposal of turbines, the actual recycling scenario was discussed, and it was observed that many metals could have a higher recycling rate than 90%, if just the materials were separated. Therefore, in this case we have calculated with a total separation of materials and a recycling rate of 95% and 100% recycling rate for just the metals.
The following scenarios for recycling of metals have been estimated:
• The actual, as described in Table 5.1. • 100% recycling of metals • 95% recycling of metals.
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Environmental impacts at various recycling scenarios for metals for Horns Rev offshore wind farm
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
-0,0040 -0,0035 -0,0030 -0,0025 -0,0020 -0,0015 -0,0010 -0,0005 0,0000 milli-person equivalents, mPE/kWh
100% recycling 95% recycling Current scenario
Figure 7.6: Sensitivity assessment for recycling of metals at Horns Reef wind farm.
Figure 7.6 only shows the life stage disposal at Horns Reef wind farm. Therefore the negative values, which are equal to a crediting of the recycled materials. It also shows that there is a direct connection between all the environmental impacts and the degree of recycling. It is important to notice the numbers on the x-axis. The values are here very large in comparison with the total environmental profile for 1 kWh electricity from Horns Reef wind farm.
Subsequently the total environmental profile for Horns Reef wind farm has been shown under the assumption of the various scenarios for recycling of metals
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Comparison environmental impacts of 1kWh from Horns Rev offshore wind farm with various recycling scenarios
Radio active waste
Hazardous waste
Bulk waste
Eco-toxicity
Human Toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-person equivalents, mPE/kWh
Current scenario 95% recycling 100% recycling
Figure 7.7: The total environmental profile for Horns Reef wind farm with various recycling scenarios for metals.
The above figure shows that recycling of metals is very import for the total environmental profile regarding 1 kWh electricity from the offshore wind farm.
8. Shortcomings Basically, all incoming substances and materials for the turbines and transmissions have been included in present LCA. However, since it has been difficult to obtain LCA data on several substances, it has been necessary to make certain assumptions. This applies for Prepreg, glue and electronic components, among other things. For each of these materials there has been made assumptions and simplifications, as described in chapter 5. More specific LCA-data on these materials would be very welcome, but access to more specific data depends very much on the individual producers and they tend not to be very willing to share the contents of their products due to competition considerations.
Sub-contractor’s energy consumption has not been stated, but in several cases a certain level has been assumed, while in other cases no energy consumption has been stated. E.g. no energy consumption has been stated for casting of cast iron components such as, blade hub (11% of the blade’s total weight), main beams (15% of the nacelle’s weight), main shaft (10% of the nacelle’s weight) and yaw ring (1% of the nacelle’s weight). A sensitivity assessment (see section 7.2) has proved that the energy consumption for casting does not have great impact on the energy balance. On that basis it has been estimated that the lack of and incomplete energy consumption has less impact on the total assessment.
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9. Conclusions In this project a LCA has been prepared for an offshore wind farm – Horns Reef – and an onshore wind farm – Tjæreborg, respectively, including grid connection. These LCA-models for wind farms have been improved compared to the initial model, which had been prepared in connection with PSO 1999.
This life cycle assessment has shown that the environmental impacts per kWh electricity delivered from the two wind farms are close to being identical within the expected uncertainties of the results. Still, there is a significant difference of the impact of hazardous waste between the two farms, as Horns Reef wind farm gives a significantly larger impact than Tjæreborg wind farm. This is due to larger quantities of metals, which are used on the offshore wind farm and that a quantity of steel is left behind on the seabed. The quantity of steel on the seabed means that this steel will not be reused, but all the costs for the manufacturing are ascribed to the offshore farm, which means that it will contribute to hazardous waste
Tjæreborg onshore wind farm has been sited at an extremely wind-optimal area and also under better wind conditions than most of the onshore wind farms in Denmark. Analyses have shown that from the expectedly worst sited offshore farm the environmental impacts will be on level with, or better than the average onshore wind farm. At the same time, the best situated onshore wind farm will be environmentally better than the worst situated offshore wind farm.
If the impacts of the two farms are compared with average Danish electricity 1997 from a previously performed LCA-project6 it shows that the impacts from the wind farms are insignificant compared to Danish electricity’97.
The environmental impacts primarily derive from the manufacturing process of the turbine and to a less degree from the manufacturing of the transmission system. The operation does not have a very large impact on the total environmental impacts, neither for the offshore wind farm nor the onshore wind farm.
During the manufacturing of the offshore turbines it is primarily the nacelle and the foundation which are contributing. The foundation constitutes the largest component when it comes to weight and consists only of steel, which has been found to contribute a lot to most of the environmental impacts. The large share of the nacelle can for the major part be ascribed to the consumption of high-strength steel. For the onshore turbines it is primarily the nacelle, the blades and the tower. Again the largest contributions derive from the nacelle due to the use of high-strength steel. The blades give large contributions to bulk waste, simply due to the fact that the blades are assumed to be deposited. Large quantities of steel are used for the tower, and here the steel gives significant environmental impacts.
When the total turbine’s lifetime has been included the energy balance shows a payback period for both farms for 9.0 months for Horns Reef wind farm and 7.7 months for Tjæreborg wind farm, respectively. I.e., the farms need be in normal operation for 7.7 - 9 months in order to produce the same amount of energy as used in their lifecycles.
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References
1 Elsam Engineering report 01-082. 1st June 2001. 2 Information from Eltra, 2002. 3 Life cycle assessment of turbines PSO 1999. Elsam Engineering 2001. 4 Annual Report 2000. Vestas. Containing environmental statement. 5 Visit on the Danish Stålvalseværk, Frederiksværk, and conversation with Nikolaj Ladegård. The 1st February 2001. 6 Life cycle assessment of Danish electricity and power planted heat. 2000. Elaborated by Elsam, Energy E2, Elkraft, Elfor, Eltra, Copenhagen’s Energy, NESA, VEKS and ELSAMPROJECT A/S (current Elsam Engineering A/S). 7 The Plastic industry’s homepage: http://www.plast.dk/public_html/070mil.htm 8 Working Report from Danish Environmental Protection Agency No. 16 2001 ‘Explanation about the environmental declaration of consumer electronics – from knowledge to action’. Prepared by Heidi K. Strandorff, Jakob Zeuten and Leif Hoffmann dk-TEKNIK Energy & Environment. 9 See www.apme.org 10 Environmental Statement 1999, Aalborg Portland. 11 Personal communication with Erik Andersen - Elsam Engineering. 12 Environmental design of industrial products. UMIP. Henrik Wenzel, Michael Hauschild, Elisabeth Rasmussen, Institute for Assessment of Products, Technical University of Denmark; The Danish Ministry of Environment, Danish Protection Agency; Danish Industry. 1996. 13 Presentation of VVM for wind farm at Tjæreborg Meadows. Prepared by Elsam Engineering for Elsam January 2001. 14 Offshore turbines Horns Reef. Assessment of Impacts on the Environment, VVM-statement, May 2000. Prepared by Elsamprojekt A/S (current Elsam Engineering) for I/S Elsam and Eltra amba.
Appendix 1
Comparison of environmental impacts of various foundation types to Horns Reef offshore wind farm
Radio active waste
Dangerous waste
Volume waste
Eco-toxicity
Human toxicity
Nutrient salt load
Acidification
Ozone depletion
Global warming
0,0000 0,0002 0,0004 0,0006 0,0008 0,0010 0,0012 milli-person equivalents, mPE/kWh
HR - Mono pile HR-Shearlegs HR-Gravitation
Appendix 1 for note no. 200128: "LCA of offshore and onshore sited wind farms". Environmental impacts of 1 kWh from Tjæreborg onshore turbine farm divided on turbine and 10kV cable
Radioactive waste
Dangerous waste
Bulk waste
Eco-toxicity
Human toxicity
Nutrient enrichment
Acidification
Ozone depletion
Global warming
0,0000 0,0001 0,0002 0,0003 0,0004 0,0005 0,0006 0,0007 0,0008 0,0009 0,0010 milli-person equivalents, mPE/kWh
Turbines 10 kV cables to transformer
Appendix 1 for note no. 200128: "LCA of offshore and onshore sited wind farms". Appendix 2
Vestas Wind Energy Danish Environmental Product V80 – Off Shore Farm Declaration (EPD) Based on LCA elaborated after ISO14040 and Northern manual for Environmental Product Declaration.
Produced by: Tech-wise A/S (now Elsam Engineering A/S) Web: www.techwise.dk Contact: Henriette Hassing Telephone: 7923 3333 E-mail: [email protected] ([email protected])
Vestas Wind Systems A/S Web: www.vestas.dk Contact: Tina Skov-Pedersen Telephone: 9675 2575 E-mail: [email protected]
EPD certificate no.: Approved by: Valid to:
Background information:
Content of LCA to offshore farm: Manufacturing of turbine and the transmission grid, operation of turbine farm, lifetime, transport to the site and to scrapping after lifetime and dismantling and scrapping of turbine and transmission grid after lifetime
Year of examination: 2002 with the basis of data from 2001
Functional unit: 1 kWh produced from Vestas V80 offshore farm
Lifetime: 20 years
Production site: Horns Rev
Market area: Denmark
Page 1 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f Life Cycle Analysis and System Delimitation
Technical/functional description
The following products comprise 1 kWh electricity produced from Vestas V80 – 2.0MW turbine farms at Horns Reef.
The system comprises foundation, tower, nacelle and blades to offshore turbine and transformer station, sea cable, cable junction station and onshore cable to grid connections. Net loss of the transmission grid has also been included in the system, but 150 kV transformers on shore are not included in the system.
System Boundaries
Crane & transport Materials & transport Production of various Energy & components of turbine materials
Erection & Operation & Dismantling & scrapping transport Maintenance
Production of various
components of the Waste Energy & transmission grid Waste materials Reuse of materials
Allocation
Allocation is not relevant for turbines, as turbines only produce electricity and not heat. The allocation is e.g. used at allocation of fuels consumption by combined electricity and heat.
Resource consumption
The most important resource materials (g/kWh): Manufacturing/ Ope- dismantling ration Transport Total Renewable resource Water for electricity production 499 18 0.03 517.03 General water 66.63 4.62 0.005 71.255 Not renewable resource Coal 0.73 0.06 0.00E+00 0.79 Iron 0.42 0.004 0 0.424 Natural gas 0.364 0.025 0.002 0.391 Oil 0.994 0.191 0.026 1.211 CaCO3 0.16 0.004 0 0.164 Brown coal 0.21 0.02 0 0.23 Aluminium (Al) 0.02 0.004 0 0.024 Uranium 4.45E-05 3.50E-06 6.49E-10 4.80E-05
Page 2 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f
Energy consumption
120 Renewable energy
100 Nuclear power plant KJ/kWh Fossil fuel 80
60
40
20
0
Manuf./dism.. Oper. Transport
Totally energy consumption (KJ/kWh)
Manufacturing/ Ope- dismantling ration Transport Total Fossil fuel Coal 18.25 1.5 0 19.75 Oil 41.748 8.022 1.092 50.862 Gas 17.836 1.225 0.098 19.159 Brown coal 5.25 0.5 0 5.75 Renewable energy Water 25.93 0.96 0.002 26.892 Nuclear power plant 4.90 0.380 7.29E-05 5.28
Page 3 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f
Emissions and environmental impact
100% 80% 60% 40% 20% 0% Global Ozone de- Acidifi- Nutrient Human Eco- Bulk Hazardous Radio active warming pletion cation Enrichment Toxicity toxicity waste waste waste Transport 1,01E-05 0,00E+00 8,67E-06 5,95E-06 1,31E-06 1,01E-10 1,37E-07 1,81E-14 2,04E-11 Operation 9,76E-05 1,02E-07 5,83E-05 3,33E-05 8,43E-06 1,27E-05 3,52E-05 3,87E-05 5,84E-05 Manufact./Dismant. 8,13E-04 6,59E-06 4,38E-04 2,23E-04 8,62E-05 1,99E-04 9,61E-04 7,32E-04 5,21E-04
Manufact./Dismant. Oper. Transport
The environmental effects are calculated by means of the Danish Environmental Protection Agency’s EDIP pc-tool.
Manufacturing/ dismantling Operation Transport Total Air emissions [g/kWh] [g/kWh] [g/kWh] [g/kWh] CO2 6.8 0.73 0.09 7.62 CO 0.023 0.002 0.0007 0.026 NOx 0.05 0.007 0.001 0.058 SO2 0.02 0.002 1.62E-04 0.022 CH4 5.22E-03 3.69E-04 2.55E-06 5.57E-03 N2O 2.09E-04 1.68E-05 1.91E-06 2.28E-04 Hg 4.86E-08 4.22E-09 3.8E-14 5.28E-08 NH3 7.8E-06 9.31E-07 1.91E-07 8.92E-06 VOC 1.08E-04 0 0 1.08E-04 Water emissions Tot-N 3.64E-05 0 0 3.64E-05 COD 3.1-04 1.77E-06 2.52E-07 3.12E-04
Page 4 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f Handling of waste after lifetime
After ended lifetime, the entire turbine is dismantled (after 20 years) and the transmission grid (after 40 years) and both should be sent to scrapping. The foundation is dismantled down to 1 metre below the seabed. It is assumed, that materials e.g. steel, cobber, aluminium, zinc, lead etc. are recycled, whereas insulating materials as bitumen, oil, rubber, etc. are incinerated and glass fibre, plastic (PVC), PrePreg (blade material) are deposited. The below table shows the various waste management scenarios for Horns Reef offshore farm.
Materials Scenario Steel blades 90% recycling Rust less steel 90% recycling Cast iron 90% recycling Cobber 95% recycling Aluminium 90% recycling Plastic, PVC 100% deposit Glass fibre 100% deposit Oil 100% incineration Lead 90% recycling Zinc 90% recycling
Not declarable aspects
More important elements for turbines, which have not be mentioned here, is the visual influence and the impacts on flora and fauna. These factors cannot be measured, but an environmental impact assessment (EIA) is to be undertaken for turbine projects in connection with its approval.
Page 5 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f
Vestas Wind Energy Danish Environmental Product V80 – Onshore farm Declaration (EPD) Based on LCA elaborated after ISO14040 and Northern manual for Environmental Declaration of Contents.
Produced by: Tech-wise A/S Web: www.techwise.dk Contact: Henriette Hassing Telephone: 7923 3333 E-mail: [email protected]
Vestas Wind Systems A/S Web: www.vestas.dk Contact: Tina Skov-Pedersen Telephone: 9675 2575 E-mail: [email protected]
EPD certificate no.: Approved by: Valid to:
Background information:
Content of LCA to onshore turbine farm: Manufacturing of turbine and electrical grid, operation of turbine farm, lifetime, transport to site and to scrapping after lifetime, and dismantling and scrapping of turbine and transmission grid cable after lifetime.
Year of examination: 2002 with basis on data from 2001
Functional unit: 1 kWh produced from Vestas V80 onshore turbine farm
Lifetime: 20 years
Production site: Tjæreborg
Market area: Denmark
Page 6 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f Life cycle analysis and system delimitation
Technical/functional description
The following products comprise 1 kWh electricity produced from Vestas V80 – 2MW onshore turbine farm at Tjæreborg.
The system comprises foundation, tower, nacelle and blades to onshore turbine and transformer station, 10 kV onshore cables to electricity connection. Grid loss of the onshore cable and 10/60 kV transformer in the distribution grid are not included in the system.
System boundaries
Crane & transport Materials & transport Energy & Production of various materials components of turbine
Erection & Operation & Dismantling and transport Maintenance scrapping
Energy & Production of 10 kV Waste Materials onshore cable for Reuse of Waste Electrical connection materials
Allocation
Allocation is not relevant for turbines, as turbines only produce electricity and not heat. Allocation is e.g. used for allocation of fuel consumption at combined electricity and heat
Resource consumption
The most important resource materials (g/kWh):
Manufacturing/ Ope- Dismantling ration Transport Total Renewable resource Water for el production 375 15 0 390 General water 68.3 4.7 0 73 Not renewable resource Coal 0.624 0.062 0 0.686 Iron 0.2 0.003 0 0.203 Natural gas 0.3 0.021 0.001 0.322 Oil 1.1 0.151 0.01 1.261 CaCO3 0.15 0.001 0 0.151 Brown coal 0.21 0.02 0 0.23 Aluminium (Al) 0.14 0 0 0.14 Uranium 2.78E-05 3.60E-06 3.30E-10 3.14E-05
Page 7 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f
Energy consumption
120 Renewable energy 100 Nuclear power plant Fossil fuel 80 KJ/kWh 60
40
20
0 Manuf./Disma. Oper. Transport
Totally energy consumption (KJ/kWh)
Manufacturing/ dismantling Operation Transport Total Fossil fuel Coal 15.6 1.55 0 17.15 Olil 46.2 6.342 0.42 52.962 Gas 14.7 1.029 0.049 15.778 Brown coal 5.25 0.5 0 5.75 Renewable energy
Water 19.51 0.78 0 20.29 Nuclear power plant 3.08 0.4 3.72E-05 3.48E+00
Page 8 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f
Emissions and environmental impact
100%
80% 60%
40%
20% 0% Global Ozone- Acidificatio Nutrient Human Eco- Hazardous Radioactiv Bulk waste warming depletion n enrichment Toxicity toxicity waste e waste Transport 5,05E-06 0 4,19E-06 2,79E-06 6,13E-07 1,75E-11 1,14E-07 2,81E-15 3,17E-12 Operation 8,17E-05 0 6,18E-05 3,53E-05 8,53E-06 1,29E-05 2,76E-05 3,78E-05 6,67E-05 Manuf./Dismant. 7,34E-04 6,15E-06 4,47E-04 2,37E-04 7,65E-05 1,40E-04 8,58E-04 3,47E-04 4,36E-04
Manuf./Dismant. Operation Transport
The environmental effects are calculated by means of the Danish Environmental Protection Agency’s EDIP pc-tool.
Manufacturing/ Operation Transport Total dismantling [g/kWh] [g/kWh] [g/kWh] [g/kWh] Air emissions CO2 6.1 0.69 0.043 6.833 CO 0.02 0.002 0.0003 0.0223 NOx 0.05 0.008 0.0006 0.0586 SO2 0.02 0.002 9.03E-05 0.02209 CH4 3.55E-03 4.83E-04 3.10E-06 4.036E-03 N2O 2.06E-04 2.22E-05 1.39E-07 2.28E-04 Hg 4.57E-08 5.56E-09 2.19E-14 5.126 E-08 NH3 9.1-06 1.23E-06 1.39E-07 1.047E-05 VOC 4.43E-05 0.00E+00 0.00E+00 4.43E-05 Water emissions Tot-N 2.13E-05 0 0 2.13E-05 COD 2.24E-04 1.53E-06 1.27E-07 2.257E-04
Page 9 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f
Handling of waste after lifetime
After ended lifetime (20 years) the whole turbine is to be dismantled and 10 kV onshore cables to electricity connection should be sent for scrapping. It is assumed, that materials as steel, cobber, aluminium, zinc, lead etc. are to be recycled, while insulating materials, bitumen, oil, rubber etc. are to be incinerated and glass fibre, plastic (PVC), PrePreg (blade material) are to be deposited. Below table shows the various waste management scenarios for Tjæreborg onshore turbine farm.
Materials Scenario Steel blades 90% recycling Rustles steel 90% recycling Cast iron 90% recycling Cobber 95% recycling Aluminium 90% recycling Plastic, PVC 100% deposit Glass fibre 100% deposit Oil 100% incineration Lead 90% recycling Zinc 90% recycling
Not declarable aspects
More important elements for turbines, which are not to be mentioned here, are the visual influence and impacts on flora and fauna. These factors cannot be measured, but an environmental impact assessment(EIA) is to be undertaken for the turbine project in connection with the approval.
Page 10 of 10 Appendix 2 for note no. 200128: "LCA of offshore and onshore sited wind farms". f Appendix 3 Energy Balance
Comparison of results from the Danish Wind Industry Association’s “Wind Power Note” no. 16 1997.
In April 2002, the Danish wind turbine owner’s association published a data sheet about ‘Wind Energy T4’ about the turbine’s energy balance, which indicates an energy pay- back period for a 1.5 MW offshore turbine to be about 3 months. The calculation behind this result appears from the wind turbine industry’s ‘Wind Power note 16’ from Decem- ber 1997 “The Energy Balance of Modern Wind Turbines” (hereafter WPN16). The principles in these calculations provide a basis for the below description.
The energy consumption for manufacturing, erection and scrapping of a turbine includ- ing the foundation has been calculated by means of a so-called energy multiplier, which indicates the global direct and indirect energy consumption in various trades in com- parison with their turnover (TJ/mill. DKK). So, the multipliers contain both the energy quantities, which are consumed in Denmark as well as abroad (by the energy that di- rectly and indirectly are used for producing the imported goods, which directly and indi- rectly enters into the production in question). The energy multipliers are to be found in ’Input-output tables and analyses’, which is published once a year by ‘Statistics Den- mark’. However, there is a four-year delay, so that the latest energy multipliers which exist at present are from 1999.
Based on the knowledge about the turbine’s value and the individual component’s share of this value, it is possible to estimate the energy consumption for the manufacturing of the turbine. The same applies to erection, servicing and scrapping.
In WPN16 the energy balance of a 600 kW onshore turbine, manufactured in 1995 has been set up. Connection has been included to the extent that the transformer, which is necessary in order to switch the turbine to the high-tension grid (10-20 kV), has been included. This corresponds with the delimitation made in the LCA for Tjæreborg Tur- bine Farm, where the internal grid between the turbines has been included due to the fact that the calculation in this case covers the entire turbine farm. As the article dates back to 1997, the energy multipliers for 1995 have not been available, and therefore it has been decided to perform a projecting based on the values for 1987 and 1991.
The results for the 600 kW onshore located turbine are upgraded in WPN16 to a 1.5 MW offshore located turbine based on the information about the planned offshore farms in Denmark and the offshore programme. This means that transformers and grid con- nection are not fully included in the Wind Power Note, in which the delimitation differs from the LCA, as the complete connection to the grid on shore has been included.
The energy consumption means the gross energy consumption, which includes energy which is added in the form of fuels to a site, and not the produced energy. This delimita-
Appendix 3 for note no. 200128: "LCA of offshore and onshore sited wind farms". Page 2 of 2 Doc. no.200269 tion has also been used when making up the consumption of energy at Horns Reef and Tjæreborg Turbine Farms.
By using the similar method to estimate the energy consumption for turbines at Horns Reef and at Tjæreborg, the result per turbine will be:
Direct and indirect global energy consumption (MWh/turbine) Horns Reef Tjæreborg Manufacturing a turbine 2.329 2.329 Erection and connection 2.356 573 Maintenance 896 896 Dismantling and scrapping -728 -321 Total 4.853 3.477
The results in the above table are based on information about the value of the turbines and breakdown of the components from Vestas Wind Grids A/S, whereas Elsam A/S has provided information about the value of the foundations and the transmission grid, which are part of the erection and the grid connection. Regarding maintenance, disman- tling and scrapping the values in the WPN16 have been upgraded in proportion to the value and weight of the turbines.
The turbine’s produced energy is converted into how much energy that would enter into a coal-burning power station (consumed fuels), in order to produce the same quantity of energy on a coal-burning power station.
With an annual production of 8,088 MWh per turbine at Horns Reef and 5,634 MWh per turbine at Tjæreborg, the energy payback period has been estimated to be 3.1 and 3.2 months, respectively, as shown in below table. Below table also shows a comparison with the results from a WPN16.
Electricity Primary energy Energy con- Energy recov- production consumption at sumption ery per turbine power station through a (mill. KWh) lifetime Mill kWh/year Mill TJ TJ Years Months kWh 600 kW onshore turbine 1,393 3,202 11,528 2,958 0,26 3,1 roughness class 1 2 MW onshore turbine, 5,634 12,95 46,59 13,7 0,27 3,2 Tjæreborg farm 1,5 MW offshore turbine 5,046 11,6 41,76 11,06 0,26 3,1 2 MW offshore turbine, 8,088 18,60 66,95 20,9 0,26 3,1 Horns Reef farm
The stated payback period indicates the time the turbine should be operating in order to save the amount of fuel on a coal-burning craft station, which is similar to what is con- sumed for the turbine in its lifetime.
Appendix 3 for note no. 200128: "LCA of offshore and onshore sited wind farms".