Last reviewed 19 June 2012

Last month’s feature article on the Biomass Battle described the ongoing debate between those in the power industry who wish to expand the use of biomass as a renewable energy source, and other users of wood who are facing price rises and potential supply shortages as demand for wood grows. The Government has responded with its official bioenergy strategy, published in April 2012. Those looking for concrete policies and proposals, or detailed predictions of future subsidy levels, will be disappointed. Nevertheless, the strategy does contain some carefully thought out general principles to guide the future direction of government intervention. Caroline Hand reports.

Four guiding principles

The strategy encompasses all types of bioenergy, including the direct combustion of wood or energy crops in power stations and the use of biofuels such as bioethanol and biodiesel in vehicles. Energy-from-waste, including the generation of heat and electricity through anaerobic digestion, is also included.

Bioenergy currently contributes around 2% of the UK’s national energy demand, but the strategy states that this proportion could rise to 12% by 2050. This level of growth is seen as necessary to meet our national target of an 80% reduction in greenhouse gas emissions. Over the next eight years, the UK must increase the contribution of renewables from 3% to 15% of total energy consumption in order to comply with the EU Renewable Energy Directive, and biofuels — as a flexible source of energy for electricity, heat and transport — will play an important part in achieving this goal.

  1. Policies that support bioenergy should deliver genuine carbon reductions that help meet UK emissions targets.

    The replacement of fossil fuels with biofuels does not necessarily lead to an overall reduction in carbon emissions. Biofuel production may have a significant energy cost in terms of shipping the fuel across the world (for example, much of the wood fuel used in the UK is imported from North America) or processing plant material into a transport fuel. Forests act as a carbon store and their destruction can release carbon into the atmosphere. Moreover, if agricultural land is given over to energy crops such as miscanthus, food production may be displaced and forests or other natural habitats cleared for agriculture. This is known as Indirect Land Use Change or ILUC and is very difficult to predict and quantify. Bioenergy policies such as subsidies will be informed by carbon assessments so that, as far as possible, these factors can be taken into account.

  2. Bioenergy should be supported when it offers equivalent or lower carbon emissions for each unit of expenditure than investment in alternative renewable energy sources.

    Biofuels may be relatively cheap to produce compared with other renewables such as solar or wind energy, but if their combustion is associated with higher carbon emissions the advantage is lost. This principle will determine which uses of biofuel should be supported as a cost-effective way of achieving our carbon reduction target. For example, the use of biofuel to replace fossil fuel in an existing power station satisfies this principle better than the development of dedicated biomass electricity generation. Drax’s decision not to go ahead with a new biomass power station as a result of a fall in ROCs (Renewables Obligation Credits) illustrates the outworking of this principle.

  3. Support for bioenergy should aim to maximise the overall benefits and minimise costs across the economy.

    It is this principle that takes into account the effect of bioenergy policies on other industries such as furniture manufacture, construction, paper making and waste management. The strategy does not go into detail as to how future levels of subsidy could impact these industries but assures other users of biomass that the Government will consult with them at an early stage of policy development.

  4. At regular intervals, policy-makers will review the impact of increased bioenergy deployment on wider objectives such as food security, biodiversity loss and global development.

    This principle addresses concerns about the loss of food production and damage to natural habitats in the developing world. It takes into account the impact of ILUC and the energy costs associated with the international trade in biomass. Transport biofuels must already meet sustainability criteria if they are to contribute to achieving the EU renewables target, but there is some question as to whether these criteria are satisfactory.

The main body of the strategy describes how the four principles are applied to:

  • the availability of bioenergy resources

  • determining the most sustainable means of deploying biomass

  • using biomass to help meet the 2020 and 2050 carbon reduction targets.

Biomass resources

Imports will continue to furnish most of the biomass used for fuel in the UK, but the strategy highlights opportunities to increase domestic supplies. In the UK, energy crops such as miscanthus or willow can actually be more sustainable than some food crops, eg they may be associated with higher biodiversity.

A helpful section of the report evaluates different options for woodland management. In terms of overall carbon emissions, it is better to use wood as a replacement for fossil fuels than leave the trees in the forest to sequester carbon. According to analysis produced by the Department for Environment, Food and Rural Affairs (Defra), the optimum use of woodland is management to supply a mixture of sawn timber (for furniture, construction, etc), particleboard and fuel. Neglected woodlands could be brought back into productive management under this scenario. The wood fuel would consist of otherwise unwanted offcuts, small branches and waste.

Deployment pathways

Defra has proposed four low-risk pathways for the deployment of bioenergy that conform to the four general principles. These are as follows.

  • Generation of electricity and heat through combined heat and power and anaerobic digestion, involving the recovery of energy from landfill gas, sewage gas and other wastes.

  • Using solid biomass or biomethane to provide heat for high temperature industrial processes.

  • Replacement of fossil fuel with biomass for electricity generation.

  • Biofuels for transport, providing these replace fossil fuels. This could increase in the long term if new technologies to create fuels from waste and woody feedstocks are commercialised.

Short- and medium-term policies for the period up to 2030 will concentrate on supporting these particular uses of biofuels.

An uncertain future

One of the reasons that this strategy lacks detailed proposals is the degree of uncertainty surrounding the sustainability and technical feasibility of bioenergy expansion. It is notoriously difficult to undertake accurate and meaningful life-cycle assessments of biofuel production, taking into account all the indirect impacts. It is also difficult to predict the state of global markets in 20 years’ time, and estimate how much biomass will be available to the UK through international trade.

Throughout the strategy there are frequent references to carbon capture and storage (CCS), which is not yet viable on a commercial scale. Bioenergy CCS is described as an exceptionally valuable technological option, which, if effective, would lead to net carbon removal from the atmosphere. This could mean that power generation from biomass and the production of biofuels for transport become much more sustainable options in the long term. Without CCS, Defra predicts a much smaller role for biomass generation post-2030.

There are already policies in place to support the expansion of bioenergy. These include a variety of research projects, the promised Green Investment Bank and the Renewable Heat Incentive. The Government is willing to give short-term financial support to the development of technology, infrastructure and markets.

With the safeguards inherent in the four general principles, the Government believes that bioenergy can contribute a greater proportion of our national energy demand than was hitherto thought. The Department of Energy and Climate Change’s target of 12% by 2050 exceeds the more cautious 10% recommended last year by the Committee on Climate Change. It is now for scientists and policy-makers to meet the challenges of drawing up sustainability criteria, assessing environmental impacts and developing the new technology necessary to meet this goal.