Washington, July 30 - A catalyst made out of shrimp shells may churn out faster, cheaper and greener biodiesel, according to a new study.

Xinsheng Zheng and colleagues, who led the study in China, described the development of a new catalyst produced from shrimp shells. In lab tests, the shrimp shell catalysts converted canola oil to biodiesel (89 percent conversion in three hours) faster and more efficiently than some conventional catalysts.

An energy-hungry world, concerned about global warming, increasingly puts its future fuel hopes on renewable fuels like biodiesel.

Today's biodiesel production processes, however, require catalysts to speed up the chemical reactions that transform soybean, canola, and other plant oils into diesel fuel.

Traditional catalysts cannot be reused and must be neutralised with large amounts of water -- another increasingly scarce resource -- leaving behind a lot of polluted water.

The new catalysts can also be reused and the process minimises waste production and pollution, the scientists said.

Their study is slated for publication in the Aug 20 issue of The American Chemical Society's Energy & Fuels.