WASTE TO ENERGY FOR THE DISPOSAL OF MUNICIPAL SOLID WASTE IN STELLENBOSCH: IS IT FEASIBLE?
Pieter Kriel, Advisian (WorleyParsons RSA) [email protected] Saliem Haider, (Stellenbosch Municipality RSA) [email protected]
1. ABSTRACT
The existing Stellenbosch Landfill site will run out of landfill “airspace” in the next three years and there is no suitable alternative site for a new landfill site within the municipality. A regional landfill site is also not available within the foreseeable future. WorleyParsons were appointed to do a feasibility study to ascertain whether a waste to energy plant will be an option to dispose of waste for the municipality.
The study included the various treatment technologies and waste requirements for the technologies looking at potential feedstock and the character and calorific values of waste, current recycling and waste avoidance and scale of possible operations. The placement of a plant in terms of transportation and legislation for a site with potential delivery models such as PPP.
The possible plant and technology was also considered in terms of the regional context. The paper will present the findings and recommendations of the study with the inputs from the various stakeholders and present the case for or against the installation of a WtE plant in the Stellenbosch Municipality.
2. BACKGROUND
Stellenbosch municipality is running out of landfill airspace fast. At the beginning of 2014, there was only 480 000 m3 of landfill airspace remaining at the Devon Valley landfill, and this is sufficient for just over three years as of February 2015, there is also no suitable location within a 40 to 50 km radius for a new landfill site.
In order to seek options for responsible but affordable waste management options for the municipality, WorleyParsons were appointed to study the feasibility of alternative waste treatment including Waste to energy.
The problem extends to the neighboring Municipalities and Drakenstein are currently in the EIA process for an alternative waste treatment project in order to address their own problem.
3. INTEGRATED WASTE MANAGEMENT (STELLENBOSCH DRAFT IWMP APRIL 2015)
GreenCape are currently busy with the updating of the waste management strategy for municipality through the IWMP process and have intel alia investigated the following scenarios for waste planning to address the issues that the municipality have:
3.1. Scenario 1
In scenario 1, builders rubble is diverted to a brick making factory and garden refuse to a composting facility, with the bulk of the remaining waste being landfilled at Devon Valley. Once Devon Valley reaches capacity, the waste will need to be sent to another landfill site, possible Kalbaskraal, a City of Cape Town/Regional landfill site that is in the planning phase.
3.2. Scenario 2
The separation at source, of recyclable domestic household waste. The recyclables are then sent to the Materials Recovery Facility (MRF) at Kraaifontein or a new local MRF, with residual waste being landfilled at Devon Valley, and at Kalbaskraal post closure of Devon Valley
3.3. Scenario 3
The recyclables will follow the same route(s) described in Scenario 2 and be diverted to either the local or Kraaifontein MRF. The organic stream will be sent to a local organic treatment facility, provisionally located at Klapmuts, where it can be treated using an anaerobic digester (AD). The remainder of the waste will be sent to landfill, and when the local Devon Valley Landfill is full, the waste will need to be diverted to Kalbaskraal landfill.
3.4. Scenario 4
Scenario 4 represents a collaborative approach to waste disposal. This would depend on source separation, with organics treatment at a local organic treatment facility as mentioned above and would be supplemented by other municipalities (Drakenstein and City of Cape Town) organic waste streams. Recyclables would be sent to the MRF while the residual waste would be sent to Drakenstein Municipality, which is in the process of implementing a W2E project.
3.5. Scenario 5
In this proposal no source separation occurs and it is assumes that no further separation at source will be implemented, and a mixed waste stream will need to be processed. Separation will take place either through a non-technical route (e.g. manual sorting) or through a mechanical separator (designed to separate mixed waste to produce e.g. organic waste for AD, recyclables and RDF). Three streams (as described in Scenario 3) will be produced. The organic fraction will still be sent to a local organic treatment facility, due to the ‘dirty’ nature of the recyclables produced, which may be unsuitable for processing at a MRF, this stream may be used for the production of Refuse- Derived Fuel (RDF). Once again the remainder of the waste will be sent to the Devon Valley landfill.
Table 1: Waste Streams by Weight (Tonnes/Year) and Volume (M3/Year) In 2014 Base case (2014) Density Weight Volume (m3/year) (tonnes/m3) (tonnes/year) Builders Rubble 0.75 35 633 47 510 Garden refuse 0.20 3 530 17 650 Domestic Refuse 0.593 45 332 76 445 Industrial refuse 0.593 3 668 6 185 Mixed Builders Rubble 0.75 3 221 4 295 Tyres 0.50 154 308 Soil (cover) 0.75 25 166 33 555 TOTAL 116 704 185 948
From the table above it can be seen that Builders Rubble and Mixed builders rubble are contributing significantly to the current landfill and if this waste can be diverted it will extend the available airspace of the landfill by as much as 45 000m3 per year even if 10% is retained for road construction and cover material on the landfill. This would indicate that the life of the landfill may be extended by another at least three and a half years. Although this may lead to some respite the lifespan of the landfill is still wholly inadequate for the short and medium term. Graph1: Cumulative waste generated for the various scenarios
Please note the positive cumulative effect of Scenario 4 3.6. Problem Statement
THE STELLENBOSCH MUNICIPALITY MUST MAKE ALTERNATIVE ARRANGEMENTS FOR THE DISPOSAL OF WASTE OR THE TOWN WILL FIND ITSELF IN A VERY PRECARIOUS SITUATION HAVING TO EXPORT WASTE TO NEIGHBOURS FOR LANDFILLING AT DISTANCES UP TO 50MK’S AND THIS IS NOT INLINE WITH THE CONCEPTS OF THE WASTE HIERARCHY.
4. PROJECT
The municipality realises that a solution must be found quickly and appointed WorleyParsons to investigate the feasibility of Waste to Energy or Alternative Waste Treatment as a possible solution going forward. Using the IWMP, the Vision and the Waste Hierarchy as a basis an approach was formalised to tackle the assignment.
4.1. Status Quo
The purpose of this analysis is to assess the strategic alignment of a W2E project with relevant legislation and strategy as well as institutional capacity. This assessment included the physical and technical framework within which such a project would be developed. The project concept was accordingly considered in relation to – the institutional capacity of the Stellenbosch municipality; the status quo of waste generation, collection, treatment and disposal; the waste landfill management and waste diversion needs; the objectives and/ or requirements of key legislation; the regional context of the construction of a Stellenbosch W2E facility; strategic objectives of the Stellenbosch municipality; and the financial position of the Stellenbosch municipality.
4.2. Stakeholder Engagement
A workshop was arranged with “Waste” stakeholders in and around Stellenbosch to ensure that the development of a concept for alternative waste treatment was not done in isolation and used inputs from as many stakeholders as possible. The following entities were present
WorleyParsons Stellenbosch Municipality GreenCape Interwaste Drakenstein Municipality Cape Winelands District Municipality Provincial Department of Environmental Affairs and Development Planning Outcomes of the Workshop
After very useful discussion the following themes were prevalent in the outcomes of the discourse.
The Cape Town Metro has sufficient landfill airspace for it to be able to operate for some time and can wait for the licensing of a new landfill facility before it theoretically runs out of airspace. The Cape Winelands municipalities (Breedevallei, Langeberg, Witzenberg) on the eastern side of the Helderberg Mountains have landfills that are also sufficient to accommodate waste generated within their areas for the foreseeable future. Except for the currently operating landfill sites, the municipalities of the Eastern side of the mountains (Stellenbosch, Drakenstein) do not have access to long term landfill airspace and after exhaustive studies have not found a suitable site to build a landfill that will accommodate their needs. The “Waste Problem” in the Cape Winelands is a regional issue and can only be addressed properly through co-operation between all parties.
5. WASTE TO ENERGY AS A SOLUTION
Stellenbosch currently have a licensed waste transfer facility at Klapmuts and this site has been proposed as the alternative for the Drakenstein W2E proposal if for some reason the preferred site is not suitable or has a fatal flaw which would render it inappropriate for the development of a W2E facility. The Klapmuts site does have certain advantages that could promote the site as, not just an alternative for the Drakenstein Municipality, but also as a preferred site for a W2E project for Stellenbosch.
Figure1: Proposed Klapmuts Locality
Figure2: Klapmuts Proximity to Services
The site has some positive features that promote it as a option for W2E: Proximity to railway line, Proximity to N1 National Roadway that connects most of the towns and cities in the Western Cape, On the border with Drakenstein municipality, Next to a WWTW that can use electricity directly, Very close to the MRF at Kraaifontein, Next to an Eskom distribution facility.
5.1. Waste to Energy Technologies
5.1.1. Anaerobic Digestion
Biomass is converted into a biogas through anaerobic digestion where organisms in the absence of oxygen convert the biomass into a combustible gas. The biogas created in the process is a gaseous mixture comprising mostly of methane and carbon dioxide, but also contains small amounts of hydrogen and trace levels of hydrogen sulphide. The methane in the biogas can be burned to produce electricity using a gas engine or the gas can be collected for use as fuel for heating or generation at alternative locations.
Figure: Anaerobic Digestion Facility
5.1.2. Pyrolysis and Gasification
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures (typically around 200 to 700°C) to create syngas and carbon. The pyrolysis (or de-volatilization) process occurs as the carbonaceous particle heats up. Volatiles are released and char is produced, resulting in up to 70% weight reduction. The process of converting the waste into syngas and carbon is conducted in an oxygen-starved-environment. Although similar to Pyrolysis, Gasification takes place in an oxygen-free-environment. The results are a carbon char that is greatly reduced in volume and also inert in nature and can be landfilled or often it is used for alternative uses such as to manufacture cement bricks or as road construction material
Figure: Pyrolysis Process Diagram
5.1.3. Incineration
Mass burn incineration has been and continues to be the most common method (other than landfilling) for reducing waste volume and generating energy. Incinerator burns waste in an oxygen-rich atmosphere at temperatures ranging from 1,000 to 1,200°C. Heat is directly or indirectly applied to boilers that then heat water to create superheated steam that is used to generate electricity. The remaining waste from the combustion process is normally landfilled. Incinerators do not typically require much pre-processing of waste; however, as they burn the waste, their rate of energy conversion tends to be significantly lower than pyrolysis or gasification systems. Figure: Typical concept for waste-to-energy Plant (from website of Babcock & Wilcox Vølund A/S)
5.2. Technology for Stellenbosch
Mass burn technology is prohibitive expensive for the application in a small municipality and cannot be justified for the amount of waste generated by Stellenbosch or in-fact by the surrounding municipalities. AD in conjunction with Gasification or Pyrolysis is scalable and can be applied to smaller projects and there are currently such installations being constructed and commissioned in RSA although not specifically for MSW. The main purpose of the W2E plant would be for the disposal of waste and the generation of electricity will be beneficial but not significant.
5.3. Delivery Model
There are a number of Municipal Service Partnerships (MSP’s) that are available as external mechanisms for the provision of the Waste Facility site operation and management service to the Stellenbosch Municipality Public / Public Partnership Service Contracts Operating and Management Contracts Lease Contracts Concession De-Monopolisation and new entry Full Privatisation Build - Operate –Own -Transfer (BOOT) Employee / Management Buy-Out
Key provisions of the Service Delivery Agreement/PPP Agreement should address the design, financing, construction, commissioning and operation of the Waste Facility.
Services; Project Assets; Payment; Stellenbosch municipal authority role; General Stellenbosch Municipality obligations; General Private Party obligations; Transfer of liability; Operational requirements; Inspection and step-in rights; KPA’s and KPI’s; Reporting, Information and Audit Access; Compliance with environmental obligations; Consents and Licensing; Insurance; Force Majeure and Relief Events; Material Adverse Government Action and Unforeseeable Conduct; Employment; Black Economic Empowerment; Private Party Default; Dispute Resolution; Termination and Compensation for Termination; Step-in Rights; Refinancing; Intellectual Property; Monitoring and compliance; Penalties; and General Provisions.
5.4. Legislative Framework
If the municipality does go the route of W2E, the following legislation is applicable: The Local Government: Municipal Systems Act, Act 32 of 2000 The Local Government: Municipal Finance Management Act, Act 56 of 2003 The National Environmental Management: Waste Act, Act No.59 of 2008 The National Environmental Management Act, Act 107 of 1998 The National Environmental Management: Air Quality Act 39 of 2004
6. OUTCOMES AND RECOMMENDATIONS
The municipality must make alternative arrangements for waste disposal, The municipality is part of the district and can’t do it “alone”, There is no one stop; one size fits all solution, Alternative treatment is feasible but must be scaled to purpose,
REFERENCES:
Draft Integrated Waste Management Plan Stellenbosch Local Municipality: GreenCape 2015.
Drakenstein Municipality Feasibility Study: Development of a Waste to Energy Project February 2013: Interwaste.
Integrated Waste Management Plan: Review And Update –Final Status Quo: Blackbird Trading 158 Cc 2010.
Babcock & Wilcox Vølund A/S: Website http://www.volund.dk/