The report reviews more than 90 global studies. It has been produced by the Technology and Policy Assessment function of the UK Energy Research Centre (UKERC), which addresses key controversies in the energy field, and aims to provide authoritative and accessible reports that set very high standards for rigour and transparency.
A debate has been raging about the role biomass could play in the future energy system: some say it could play a major role in fuelling the planet, others argue it risks an environmental disaster. To get to the heart of the controversy, UKERC scientists at Imperial College London have undertaken the first systematic review of the evidence base.
The report finds that the main reason scientists disagree is that they make different assumptions about population, diet, and land use. A particularly important bone of contention is the speed with which productivity improvements in food and energy crop production can be rolled out.
"If we make the best use of agricultural residues, energy crops and waste materials then getting one fifth of current global energy supply from biomass is a reasonable ambition," says Dr Raphael Slade, the report's lead author and a Research Fellow at Imperial College London. The report finds that getting more than this is technically possible but requires assumptions about food production and changes in diets that look increasingly challenging, especially as people in Asia and Latin America begin to adopt a high meat western diet as incomes rise.
"The more bio-energy you want the harder it becomes to reconcile demand for food, energy and environmental protection" says Slade. Replacing all fossil fuels with biomass would be equivalent to all of global agriculture and commercial forestry combined, and would only be possible if we can grow more food on less land.
Technical advances could be the least contentious route to increased bio-energy production, but policy will need to encourage innovation and investment. A renewed focus on increasing food and energy crop yields could deliver a win-win opportunity as long as it is done without damaging soil fertility or depleting water resources. The report highlights the potential for policy to promote learning by encouraging development of sustainable biomass now, rather than waiting for the definitive answer on the ultimate potential.
"The main mistake is to think of this as all or nothing. There's plenty of scope for experimentation to make sure we get it right," says Dr Slade.
Energy is an essential input into global agriculture, and the interactions between these two areas need to be better understood. The report stresses the need for scientists working on food and agriculture to work more closely with bio-energy specialists to address challenges such as water availability and environmental protection. If biomass is required to play a major role in the future energy system the linkages between bio-energy and food production will become too important for either to be considered in isolation.
"Bioenergy may need to play a part in a future low carbon energy mix," says Dr Ausilio Bauen, Head of Bioenergy at Imperial College's Centre for Energy Policy and Technology. "Ensuring bio-energy, food and forests don't compete for land won't be straightforward. But, if we use land more productively, and make better use of available plant material, we should be perfectly capable of producing bio-energy, feeding a growing population, and conserving the environment all at the same time."
The report is available on the UK Energy Research Centre here.