Defra’s Biomass Task Force Report to Government notes that biomass (fuel from forestry, energy crops and waste) could reduce the nation’s carbon emissions by almost three million tonnes a year if used to provide heating.
Heat generation accounts for 40 per cent of our national energy consumption. The carbon saving would be the equivalent of taking 3.25 million cars off the road. The report estimates that there could be 20 million tonnes of biomass available annually.
The section on biomass feedstock potential shows that there is a clear link with food issues; sources of biomass include animal wastes, manures and slurries, energy crops and municipal solid waste (which will include a food element).
While published estimates of feedstock volumes can vary greatly depending on assumptions made, what is clear is that significant amounts of biomass materials are available within the UK. The total, from the data we have assembled, shows 20 million tonnes of material which could be used for energy.
Wastes – both municipal solid wastes (MSW) and animal wastes – offer the greatest immediate sources of energy, with 2.5 million tonnes of MSW already being used for energy generation and a 400% increase in available tonnage anticipated by 2010. However, the development of Refuse Derived Fuel (RDF) from MSW, although offering improved handling characteristics, higher calorific values and a more consistent burn than MSW, has had restricted market penetration to date due to the need to burn it in Waste Incineration Directive-compliant plants. Also, there could be a significant contribution from forestry, wood waste and crops with what we consider to be conservative estimates totalling nearly 5 million tonnes.
Around 3 million tonnes of wet animal slurries and manures are generated annually in the UK; if 50% of these farm wastes were processed in anaerobic digesters, they would potentially contribute up to 1.1 TWh per annum of electricity, resulting in carbon savings of over 0.13 MtC per year. Co-firing has raised the profile of both forestry and energy crops as sources of biomass and, although much of the co-firing capacity currently uses imported materials, the hectarage of energy crops is increasing annually, with current combined plantings for short rotation coppice and miscanthus of around 2,500 hectares (equivalent to yields of around 25,000 tonnes per annum).
Our [the Biomass Task Force] vision statement assumes that around 1 million hectares of land may be available for non-food uses in general. This could mean around 8 million tonnes of energy crop. The development of biofuels in the UK is likely to lead to competition for feedstocks although some biofuels, or their feedstocks, will be imported.
The use of biomass generally focuses on the potential to deliver heat or electricity yet biomass also has the potential to deliver absorption cooling from the heat produced by CHP or from a district heating network. In these circumstances water is used as the refrigerant. An absorption chiller has the effect of increasing the base heat load all year round, leading to increased energy savings. Woking Borough Council has the first small scale CHP/heat-fired absorption chiller system in the UK which provides heating, hot water services, air conditioning and electricity to the Civic Offices.
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