Select Committee on Environmental Audit Minutes of Evidence



  Changes in the way electricity is generated and used are accelerating. There is a need to provide energy in a more sustainable and efficient manner, in order to reduce impacts on the global environment, and supply energy from more diverse and secure sources. Renewable energy from biomass meets these criteria but to date its development has been sporadic. The £30 million ARBRE (ARable Biomass Renewable Energy) power plant—the first plant of its type in the world—has been developed to show that there is a way to utilise and convert biomass efficiently. The project is located in Yorkshire in the north of England. It generates 10 MW of electricity and is fuelled by short rotation coppices (SRC) specially grown within the region and wood from sustainable forestry operations. The project is calculated to save around 16,000 tonnes of carbon per annum by offsetting emissions from coal fired power stations. On a life cycle basis ARBRE has a non renewable energy requirement estimated at one eighth of a modern combined cycle gas fired power station. Wood fuels are carbon dioxide neutral, meaning that the carbon dioxide released when the fuel is consumed is equal to the carbon dioxide taken up by the plants during their growth.

  ARBRE's principal objectives are to:

    —  establish 1,500 hectares of dedicated sustainable fuel supply chains based on energy crops such as short rotation coppice; and

    —  construct a high efficiency Biomass Integrated Gasification Combined Cycle (BIG-CC) power station supplied by these fuels.

  The project utilises high efficiency BIG-CC electricity generation technologies to provide sufficient electricity for the domestic needs of 33,500 people. The plant converts energy stored in wood via an atmospheric circulating fluidised bed gasification process into electricity. The principal benefits of a BIG-CC system include significantly higher plant efficiencies (and hence lower fuel usage) and a reduction of emissions to atmosphere from the combustion process. In addition to CO2 emissions, acid rain is a serious environmental problem associated with fossil fuel use. Much of this arises from the release of sulphur oxides (SOx) when fossil fuels are burnt. Wood such as that used by ARBRE has a low sulphur content, so emissions of SOx will be minimal. ARBRE also has been designed to control the level of nitrogen oxide (NOx) emissions, the second major contributor to acid rain arising from fossil fuel use.

  The site has three principal areas of operation. Wood is delivered as chips and stored and processed in a building that holds three days' supply of wood chips. The second part of the process gasifies the wood chips and cleans the resultant gas by combination of tar cracking, filtering and scrubbing. The final stage of the process is combustion of the gas in a combined cycle plant, that utilises a 4.5 MW gas turbine and a 5.5 MW steam turbine. Waste heat from the boiler is then used to dry incoming wood chips.

  ARBRE has a wood fuel requirement of 43,000 oven dry tonnes year. SRCs are grown in a radius of 60 km and on land predominantly in agricultural arable set-aside. SRC consists primarily of high yielding varieties of willow, planted at high density and harvested on three year rotations. It is classed as an arable crop, as land preparation prior to planting is similar to that for crops such as wheat and barley. SRC can be grown on land ranging from currently farmed arable land, through grassland to reclaimed colliery spoil or sand and gravel workings. The coppice root stock is left in the ground and after each harvest new shoots emerge as in a traditional coppice. SRCs provide attractive habitats for songbirds and pheasants. Second and third year willow SRC in particular attracts high densities of songbirds of recognised conservation interest; migrant warbler species occur in higher numbers in willow SRC than in other woodland types including traditional coppice.

  The project commenced in 1995 and has achieved the following successes:

    —  an international joint venture company has been established to direct and manage its progress

    —  a long term contract is in place to sell electricity under the UK's Non-Fossil Fuel Obligation

    —  a grant has been won from the European Commission's THERMIE programme

    —  an environmental assessment and planning permission for plant construction has been gained

    —  the generating plant has been designed, constructed and is undergoing commissioning

    —  the establishment of 1,300 hectares of energy crops (short rotation willow coppice)

    —  several contracts to source forestry wood supplies

  The project has also completed a number of environmental technical and financial studies. For example, an Environmental Statement studied all effects of the project, including visual, emissions to air, water and land, transport and noise, and concluded these to be insignificant. The project is being independently monitored over a two year period by the European Commission and the DTI.

  Furthermore the project has acted as a blueprint for replication of other projects in the UK, mainland Europe and elsewhere. The requirement to double Europe's energy supplies and to provide 10 per cent of the UK's electricity from renewables by 2010 will require significant contributions from biomass. In the UK it is anticipated that 1,000 MW of biomass projects are required to be developed. The DTI have announced a New and Renewable Energy programme, where an obligation will be placed on electricity supply companies to deliver the target. In Europe a Directive on Renewable Energy is planned to be adopted this year, so the importance of renewables is increasing at pace. The successful demonstration of the technology and fuel supply establishment for the first time will encourage the opening up of the biomass sector. Future ARBRE projects will be developed at 4 times greater output and will benefit from even higher conversion efficiencies. They will each require some 100,000 dry tonnes of biomass fuels and a significant part of this will come from the establishment of 7,000 hectares of energy crops.

  The development and construction of the project has combined skills in engineering, environmental management, agriculture, forestry and finance. It has made a significant and positive enhancement to the personal knowledge of the individuals who have led the project and to the staff in their teams.

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