With high oil prices and concerns over energy security and the environment prompting governments in many consuming countries to mandate greater use of biofuels in transportation,oil companies are rethinking where green fuels fit into their strategies.And since most majors don't have the specialist staff to produce the cleaner,plant-based fuels themselves,they are either linking up with firms that do or pouring money into research.The two types of biofuels now in use,ethanol and biodiesel,are made from food crops,but are often expensive and energy-intensive to produce,and less energy-efficient than fossil fuels.
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