This policy brief, published by the International Water Management Institute (IWMI), examines the likely adverse impacts of growing biofuels and outlines options for reducing these.
Rising oil prices, coupled with concerns over energy security and climate change, have stimulated interest in biofuels across the developing world.
But such crops need a lot of water — 2,400 litres for maize to yield one litre of ethanol in China for example. And growing biofuels in water-scarce areas will aggravate the already fierce competition between domestic users, industry, agriculture and the environment, say the authors.
Producing biofuels from crops such as wheat, maize or sugar cane could also impact food supplies and prices. And switching from industrial crops, such as cotton, could affect livelihoods.
Biofuel crops could also add to conflicts between environmental and livelihood goals in the water sector, say the authors. For example, in India, irrigated sugar cane for biofuel is putting pressure on the Krishna Basin, where water flow requirements are seldom met because more and more water is being withdrawn.
Policymakers, say the authors, must make sensible tradeoffs between biofuels and other water uses. They should focus on less thirsty crops such as jatropha or sweet sorghum, that are less likely to compete with food crops.
Supporting new technologies is also important. New ways of making ethanol, for example from waste straw using enzymes, might become cost-effective in the next decade and will typically require less water than traditional biofuel crops.