WTE in context

An innovative waste to energy plant forms an integral part of a bigger environmental initiative on London’s River Thames. Here, Gareth John takes us on a tour of the Cyclamax plant part of London’s Thames Gateway Sustainable Industries Park development. Aerial view of the Cyclamax plant Click here to enlarge image The UK currently generates 330 million tonnes of waste annually. More than 50% of this is sent to landfill and despite the fact that 90% is recyclable only 27% is recycled. These levels are set to increase with an annual rise in household waste production of 3%, and waste production levels expected to double by 2020. Using advanced gasification solutions which will offer an alternative to these traditional methods of waste disposal, is a central priority for the waste industry. This piece focuses on a new UK WTE project called the Cyclamax Resource Park, scheduled to open at Dagenham in 2015 in the Thames Gateway’s Sustainable Industries Park. It will provide a critical solution to sustainable waste management in the area. Background Cyclamax, a leading WTE company, is dedicated to establishing and managing WTE resource parks through the UK. It is currently developing four gasification and recycling-led resource parks, which will employ gasification techniques aimed at removing the need for landfill. The parks are being developed in partnership with SITA UK, a recycling and waste management company which delivers environmentally responsible solutions to waste disposal for the public, local government, industry and commerce. Annually, SITA UK serves over 12 million people and handles 10.9 million tonnes of waste through a number of composting, WTE and landfill facilities. Their aim is to sustainably utilize the resource in waste generated by local businesses. Cyclamax: Why the Thames Gateway? Against a backdrop of increasing volumes of waste in the London region (projected to increase to 24 million tonnes by 2020), the Cyclamax will provide a sustainable waste disposal alternative to serve the increasing amount of waste generated in the Thames Gateway. The Thames Gateway is set to become a central hub for the environmental technologies sector in the UK. The London Sustainable Industries Park (SIP), which is being developed by the London Thames Gateway Development Corporation (LTGDC), has been envisaged to house the largest concentration of environmental technologies companies in the UK. Tony Watkins, Managing Director of Cyclamax said, ‘We looked at many sites and had other options in other parts of London but the Thames Gateway is clearly the best location for our business. What we see here at the Sustainable Industries Park is the embodiment of an opportunity to try and handle and deal with some of the challenges [of waste management] in a sustainable way.’ The benefits for the Thames Gateway region The Cyclamax plant will be the first WTE partner in the Sustainable Industries Park. It will treat industrial and commercial waste from the local area and form part of the integrated power supply for the whole of this resource park. As a community-level operation, the Thames Gateway’s Cyclamax will help the Sustainable Industries Park to become self-sustaining and carbon neutral. The plant, using its advanced gasification techniques, will convert around 120,000 tonnes of waste generated at the Sustainable Industries Park into 16 MW of energy. The park will also provide renewable and low-carbon electricity to the local network, which will be enough to supply the needs of 31,500 households in the borough of Barking and Dagenham. This accounts for approximately 45% of the households in the area. By generating power from materials that traditionally would have been added to landfill, the Cyclamax expects to save 46,000 tonnes of CO2 per annum the equivalent saved by taking 20,000 cars off the road. The excess heat generated by the plant will also tap into the proposed district heating main in the Sustainable Industries Park and the new housing development at nearby Barking Reach. The Cyclamax at Dagenham: day-to-day operations There will be six modules in the Thames Gateway Cyclamax, each of which has four primary gasification chambers and one secondary combustion chamber. The four primaries go through a sequenced batch operation to ensure a constant supply of syngas to the secondary combustion chamber. Architectural view of the Cyclamax plant Click here to enlarge image The gasification technologies employed, whereby waste materials are converted into gas under anaerobic conditions, will deliver energy at the scale required using the following process: 1. Residual waste delivery Residual waste that has already been subjected to sorting is delivered to the gasification plant. All waste is tipped inside the buildings. The waste will have a second inspection at this point and non-conforming wastes will be separated out for disposal at a licensed facility. 2. Gasification of the waste The residual waste is then loaded into the primary gasification chamber where the waste materials react under a high temperature with only a very small amount of air. The amount of air is carefully controlled and monitored so that the waste volatilizes, but doesn’t burn in an uncontrolled manner as a bonfire might. Volatilizing the waste ensures that it does not burn, but instead generates a gas referred to as a synthesis gas, or syngas, which is principally made up of hydrogen, methane and carbon monoxide. There are no emissions of any kind from this gasification stage. 3. Syngas combustion The syngas from the primary chamber is piped off into the secondary combustion chamber where the gases are completely combusted. 4. Steam generation The heat generated by these combusted gases is then passed through a boiler where the heat is rapidly exchanged to heat water and produce steam. 5. Electricity generation This high pressure steam can then be used to generate renewable electricity using steam turbines. 6. Exhaust gas clean-up The combusted and, by now, cool gases finally go through flue gas treatment with bicarbonate of soda to neutralize any acids, urea to remove nitrogen oxides and bag filters to capture dust. 7. Flue Once the gas has gone through the exhaust gas clean up it is then passed through the flue and into the atmosphere. Emissions from the flue are strictly monitored by the Environment Agency and must comply with European legislation. Operators overseeing the equipment at Cyclamax Click here to enlarge image Overall, the Cyclamax at Dagenham will process 120,000 tonnes of waste annually and provide enough power to contribute to the daily running of the Sustainable Industries Park and local residences. The decision made by Cyclamax to locate their pioneering waste-to-energy resource park in the Thames Gateway demonstrates how the region represents an exciting hub for growth for the recycling industry. Gareth John, Director of Invest Thames Gatewaye-mail: [email protected] Gasification: an overview Gasification has been used since the late 1800s to make gas for street lighting and cooking in the home. It’s a process which can take non-inert materials and convert the solid materials to a gas (synthesis gas or syngas) made up of differing proportions of hydrogen, carbon monoxide and some methane. Gasification uses the principles of combustion, but the conditions are controlled so that they remain sub-stoichiometric, that is to say one part of the reaction is at a level less than required for the perfect reaction. In the case of gasification, the oxygen levels are kept purposefully low so that the combustion reaction only gets to the volatilization stage where combustible gases are produced. >The low level of oxygen ensures that these gases cannot combust themselves to complete the combustion reaction where all energy in the waste materials is then spent. The syngas generated can then be tapped off and used elsewhere for a multitude of applications. Gasification is a highly efficient process whereby virtually all the energy in the material being gasified is released into the gas and, therefore is a very efficient method of generating steam and electricity from waste materials. Waste types accepted for energy generation will include packaging which is too contaminated for recycling, treated wood wastes, damaged and/or out of date stock from supermarkets and other wastes which are too low in value to recycle. More Waste Management World Articles Waste Management World Issue Archives