The UK's newest EfW plant

by the CADDET UK National Team

Built at a cost of 40 million, one of the latest in the new generation of energy-from-waste (EfW) plants in the UK is now up and running at Teesside in north-east England.

The new plant complements five other state-of-the-art EfW facilities around the UK which are helping to ensure that incineration with energy recovery plays a role in developing an integrated and sustainable system for managing the UK's waste.

The owners and managers of the new Teesside plant are Cleveland Waste Management (CWM), a joint venture between Northumbrian Environmental Management and the former Cleveland County Council. The facility will be used to dispose of the domestic waste produced for the next 25 years within the area served by the local district councils of Hartlepool, Stockton, Middlesborough, Redcar and Cleveland. A further 25-year contract has also been signed to handle a proportion of the waste produced by North Tyneside Council.

As for power sales, a 15-year contract under the UK's Non-Fossil Fuel Obligation (NFFO) began in May 1998. Since then, the plant has been generating around 20 MW of electricity ­ enough to meet the needs of around 20,000 homes. It is also hoped that, within a year, the 65,000 tonnes/year of bottom ash produced by the facility, which currently goes to landfill, will be re-used as a substitute aggregate. This will further enhance the plant's environmental performance and so help the local councils meet their recovery and recycling targets.

The process
Waste is brought to the plant by lorry and tipped into a 3,500 tonne capacity storage pit. Together, the local district councils are under contract to supply CWM with at least 180,000 tonnes/year of waste. This represents around two-thirds of the overall amount of municipal solid waste generated in the area covered by the councils. The gate-fee is currently less than the fee they would pay if their waste was disposed of to local landfill, a position which will improve further as landfill tax rates increase.

An overhead crane is used to lift the waste out of the pit into a pair of hoppers, which feed the two incinerators. Each incinerator burns waste at a rate of 16 tonnes/hour. The heat produced is used to raise the temperature of the water in a circulation boiler to 400C. Superheated steam from the boiler is then harnessed to turn a single-cylinder turbine linked to an electricity generator. The power produced is sold to Northern Electric plc under the terms of the NFFO contract.

The incineration process reduces the waste by 90% in volume, leaving only ash and clinker as by-products. Ferrous metals are reclaimed from the ash magnetically. After being fed through a trommel, where any excess ash is shaken off, the metals are baled and dispatched to British Steel for recycling. At present, the inert ash that remains is sent to landfill, though in the future, it could be used as a construction material or aggregate. Using the ash as aggregate would increase the recycling rate of the Teesside plant from the current 5% to around 30%.

The plant is fully computer-controlled and incorporates fail-safe shutdown systems. Shift teams ensure that operation­and power generation­is continuous. The safe, efficient working of the facility is also guaranteed by the duplication, or in some cases triplication, of many of its components.

Environmental issues
To ensure that emissions from the plant comply with European legislation, sophisticated flue gas cleaning techniques are employed to remove gaseous and particulate pollutants produced by incineration of the waste. These techniques include acid neutralisation through treatment with lime, dioxin elimination through treatment with activated carbon, and removal of large particulates through the use of bag filters. The environmental standards that the Teesside facility is obliged to meet are set out in its Environment Agency authorisation, and these have been bettered in independent tests undertaken since commissioning.

The development of close links with the local community is a stated aim of CWM. As well as liaising with and informing local residents to try to ensure that any concerns they may have about the plant or its operation are alleviated, this also involves investing in community education, recycling and other appropriate projects.

The site has been landscaped to a high standard in consultation and collaboration with the Tees Valley Wildlife Trust. Features designed to encourage local wildlife have been incorporated and a near-natural habitat has been provided for a wide range of plant species, several of which are considered rare or endangered within the Teesside area.

For more information contact the CADDET UK National Team in Oxfordshire.

Schematic of the Teeside plant.

The CADDET Renewable Energy Newsletter is a quarterly magazine published by the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors. They do not necessarily reflect the official view of CADDET.

Enquiries concerning the Newsletter should be addressed to Pauline Toole, Editor, CADDET Centre for Renewable Energy, ETSU, Harwell, Oxfordshire OX11 0RA, United Kingdom. Tel: +44 1235 432968, Fax: +44 1235 433595.