Case Study 06 Lerwick District Heating

Owner of District Project Description Key Features Heating: Lerwick is the capital of the • Energy recovery plant Shetland Charitable Shetland Islands and is home (waste–to–energy). Trust to around 8,000 people. • District heating system. A district heating scheme utilising • 300 m3 peak–load thermal store Owner and Operator an energy–from–waste plant • Peak load oil fired boiler station. of ERP: has been successfully installed, providing heating and hot water Shetland Islands to the residents of Lerwick for the Council last decade, and there are now plans to expand the scheme to Operator of District serve more customers. Heating: Shetland Heat Energy Key Drivers and Power (SHEaP) In 1991, the existing Shetland Island incinerators were decommissioned CHP Consultant: due to non compliance with EU Peak load boiler station and thermal store Reproduced with permission of SHEaP COWI legislation. This presented a waste (Aarhus, Denmark) disposal issue for the area and Procurement the use of waste incineration has During the early stages of the Location: the benefit of diverting waste from landfill. project, discussion with Scottish Lerwick, Shetland, and Southern Energy (SSE) was Scotland Shetland was not connected to the undertaken by the Shetland Isles UK electricity grid and was without Council (SIC) to investigate the Building Types: mains gas. Consequently, fuel costs potential of a joint venture to Domestic were among the highest in the establish a district heating scheme Public Buildings UK and the fragile economy was for Lerwick, firstly using waste heat Community Buildings susceptible to energy costs. from the Lerwick power station operated by SSE, and subsequently Commercial The Shetland islands are exposed from an energy–from–waste plant. to the North Atlantic and North Sea Industrial However, SSE later withdrew from winds, which result in high heating the project and The SIC approached demands. This presented a good Renewable The Shetland Charitable Trust. opportunity for district heating, Technologies: A limited company, Shetland Heat the feasibility of which is dependant Energy and Power (SHEaP), was on a high heating density. Waste to energy then set up by the Trust to operate District heating

Case Study 06 – Lerwick District Heating the scheme. Heat generated by Despite promotion of the scheme the ERP is sold to SHEaP, who then via local media, public presentations distribute and sell it to customers. and set up of a “shop”, low oil prices in the late 1990s meant that A waste study undertaken identified sign up by large customers was that in order to successfully very slow. However, early sign up implement an Energy–from–Waste by domestic customers (who had scheme, waste would need to be some prior experience of district obtained from a number of sources. heating in Scandinavia) and a street of council owned property which Waste Stream Quantity was then undergoing refurbishment (t/yr) began to promote the scheme Shetland municipal waste ~ 15,000 through word of mouth. Orkney municipal waste ~ 8,000 To incentivise customers for early ‘Residents find that Waste from offshore oil industry ~ 3,000 sign up, EU Thermie funding was made available. The funding they can heat their Summary table of waste sources and approximate quantities for ERP provided a 30% grant towards whole property Reproduced with permission of the conversion cost (with a free quickly, and can Shetland Isles Council connection) to any customer who signed up to the scheme before heat areas which Procurement of waste from the distribution pipe network was Orkney was facilitated through were always cold laid past their property. the Orkney and Shetland Waste with previous Plan (SEPA, 2003). Offshore waste A high level of customer sign up oil fired heating generated by Shell, who operated was also important to minimise systems’ a ‘zero offshore waste to landfill’ waste heat ‘dumping’ when heat Neville Martin, policy, was also sent to the plant. demand dropped significantly. Changes in waste composition Heat ‘dumping’ is a mechanism SHEaP have occurred since commencement of removing excess of surplus heat of the scheme due to increased production. Initially, air coolers levels of recycling and a greater were frequently used to dump quantity of waste plastic packaging. surplus heat. This has now reduced Consequently, waste is now also somewhat with the scheme now sent to the ERP by the Highland producing around 50,000 MWh Council. per annum with annual customer sales at around 35,000 MWh (i.e. a surplus of 15,000 MWh, a significant proportion of which is ! lost through the distribution system.) Dumping of surplus heat is now only undertaken during summer months when the average heat demand drops below a set level. Further reduction of summer dumping cannot currently be achieved without significantly Composition of Shetland municipal solid waste Reproduced with permission of more connections. This in turn Shetland Isles Council would require an additional cheap heat source for the winter.

Case Study 06 – Lerwick District Heating A significant sum is saved by large customers, and the need to install localised expensive heating plant is removed for new large customers.

Technology selection process The lack of mains gas meant that conventional energy sources Back up oil fired boilers in boiler station available to Shetland were limited. Reproduced with permission of SHEaP Consequently, the use of waste as an energy source, via district Scheme costs heating, was a desirable alternative The initial construction of the ERP for the Shetland Islands Council cost in the region of £11 million (SIC) when it was first considered in 1999. As of the end of 2010, in the 1990s, with the additional the cost of the district heating benefit of diversion of waste from was approximately £13 million, landfill. An energy recovery plant, including the cost of all plant and for heat only rather than combined infrastructure serving a total of heat and power, was decided upon around 1100 properties, 110 of due to the significant cost increase which are non domestic but take associated with electricity generation approximately 60% of the heat. for only marginal efficiency improvement. Maintenance costs of the main network are covered by SHEaP, The energy recovery plant (ERP) with customers responsible only is located in an industrial area for maintenance of plant within to the north of Lerwick, near the their property boundary. A notable dock to minimise the transport proportion of annual maintenance distance required for offshore waste costs, at around £150,000, deliveries. A peak–load boiler are associated with alarm systems station (PLBS) and thermal store and mechanical muff joint issues were constructed on land adjacent in the pipe network. However, these to the Lerwick power station, issues could now be resolved with approximately 1.6 km south of the technological advances in pipe ERP. The thermal store has a storage design made since installation capacity of approximately 12 MWh of the scheme. and is used in preference to the oil fired boilers whenever possible. There are a number of economic The main distribution and return benefits of the scheme. pipelines connecting the ERP and Approximately £3 million/year PLBS to customers run underground is retained in the local Shetland to Lerwick. The plant operates at economy which would have around 80% thermal efficiency and otherwise been spent on oil or serves approximately a third of the electricity for heating. Additionally, buildings in Lerwick. around £500,000 of local employment is generated every year due to distribution pipe laying and plumbing requirements.

Case Study 06 – Lerwick District Heating Monitoring and operation A contentious issue with energy from waste is the production of potentially harmful flue gases and precipitates. Flue gases are cleaned in compliance with the waste incineration directive, with contaminant concentrations continuously monitored and spot sampled. It has been argued that as a high proportion of dioxins Connection branch pipes to customer properties Reproduced with permission of SHEaP generated in the UK originate from unmonitored domestic fires and stoves, by replacing individual SHEaP hold responsibility for all heating systems with district plant and distribution pipes up to heating, the Lerwick scheme has the valves located just inside the actually reduced dioxin emissions customer property. Customers are in the area. responsible for the installation of heat exchangers and valve A study was undertaken to calculate connection within their properties, estimated annual savings in by approved plumbers only. greenhouse gas emissions and fossil SHEaP provides the meters for the fuel imports. Data was collated on approved plumbers to install. the individual customer heating systems used prior to installation Monitoring of customer of the district heating scheme, in consumption is achieved via addition to operational efficiencies ultrasonic meters, which report of energy production. For the temperature and flow conditions purposes of the study, the ERP was in addition to heat demand in kWh. considered as carbon neutral on the Meter readings are relayed back to assumption that the biodegradable the office on a quarterly basis via waste 85% burnt in the ERP would a system installed in 2007, although have otherwise been sent to approximately 10% of meters are landfill and eventually degraded still read by a handheld receiver to methane. for location reasons. The original study estimated The ERP is now almost operating that utilising waste as an energy at capacity and consequently no source saves approximately further connection applications are 4000 tonnes a year of fossil being considered until an additional fuel imports. This saving is now heat source is identified. Potential estimated at approximately options to provide this heat include: 6000 tonnes. Carbon dioxide • generation of off–grid electricity savings were originally calculated by wind turbines, used to create at approximately 12,000 tonnes heat using large scale immersion a year although this is now closer heaters and a thermal store. to 15,500 tonnes. The benefit of this option is that the windiest conditions tend to The annual carbon dioxide savings coincide with higher heating of 15,500 tonnes a year equate to demands (due to wind–chill) approximately 1.9 tonnes for each therefore load matching may resident of Lerwick. be more easily achieved;

Case Study 06 – Lerwick District Heating • collaboration with other Financial lessons: schemes to take advantage • The type of pipe system installed of economies of scale for the can have a significant effect on import of biomass such as wood maintenance requirements and pellets, in conjunction with other so should be considered from renewable energy sources such as the early design stage. heat pumps, thermal stores and • Share trenching with services wind turbines; or for new build developments • use of waste heat from a new and build additional capacity power station proposed by SSE into trenches/ducts (this may in the ERP. provide an additional source of rental income). Lessons learnt

Technological supply issues: ‘District heating • Meter all properties and use systems are a remote metering system. well suited to • Keep the organisation small and source specialist services areas which are externally. not served by • Use twin steel pipes with mains gas’ electrofusion joints for Neville Martin, distribution system. ERP operated by Shetland Islands Council Reproduced with permission of SHEaP Occupant involvement: Shetland Isles Council • Create incentives for customers to sign up to the scheme from Awards and Achievements the outset. • Environmental Award for • Utilise the local community Engineers (Engineering Council, and workforce as far as possible 2000); and for effective implementation • ICE James Watt Medal awarded of scheme (e.g. use of local, for a technical paper written about approved plumbers for heat the district heating scheme (2011). exchanger installation). • Maintain a high level of customer contact.

Case Study 06 – Lerwick District Heating References and Further information Acknowledgements Shetland Heat Energy and Power N Martin and W. Spence., 2009, Limited Lerwick district heating scheme www.sheap–ltd.co.uk Shetland Islands, UK, Energy (163, issue EN3), pages 131–138, ICE Neville Martin, Shetland Isles Council

These case studies are presented to show examples of how buildings can be designed and built to be low carbon and incorporate renewable and low carbon technologies. This case study is part of a Practice Guidance series of case studies supporting Renewable and Low Carbon Energy in Buildings a separate practice guidance document on low carbon buildings. For further information see 1 Introduction

www.wales.gov.uk/planning July 2012 WG14120 ISBN 978 0 7504 7707 9 Crown Copyright 2012

Case Study 06 – Lerwick District Heating