Dedicating crops and land to biofuel production will undermine efforts to combat climate change and feed the planet, according to a new report published Thursday by the U.S.-based think tank World Resources Institute. Firstly, turning plants into liquid fuel or electricity is inefficient. Providing just 10% of global transportation fuel from biofuels in 2050 would require an additional 30% of the total energy in all the crops currently produced, the report found. Meeting 20% of the world’s total energy demand by 2050 with bioenergy would even require humanity to at least double the world’s annual harvest of plant material, including plant residues, grass and timber. Secondly, using land for bioenergy production increases the competition for fertile land, the report found. So-called “second generation” technologies, which use crop residues or other wastes, could also lead to competition since most of these residues are already used for animal feed or needed for soil fertility. Increasing biofuel production at a meaningful scale therefore comes at the cost of growing food, animal feed or storing carbon. Thirdly, biofuels do not cut greenhouse gas emissions as much as previously thought. According to the authors, most calculations claiming that bioenergy reduces greenhouse gas emissions relative to burning fossil fuels do not include the carbon dioxide released when biomass is burned. This is based on the theory that these emissions are matched and implicitly offset by the carbon dioxide absorbed by the plants growing the biomass. However, if those plants were grown anyway, for example for food, simply diverting them to bioenergy does not remove any more carbon from the atmosphere. Emissions even increase if forests are cleared to generate bioenergy or to replace fields that were converted to growing biofuels. The report identifies some forms of bioenergy which do not compete for food or land and could reduce greenhouse gas emissions. Examples include growing winter cover crops for energy, timber processing wastes, landfill methane or wood from agroforestry systems. But their potential to meet a considerable share of human energy needs is limited. (ab)