Many experts have also become concerned about biofuels' questionable green credentials.

However, some in the industry argue that there are biofuel crops that don't require agricultural land

Oxburgh stresses that jatropha—a hardy plant from which his company, D1 Oils, extracts oil to make biodiesel—will not compete with food for land, nutrients, or water

"Biofuels are getting a bad name because people are using food crops to produce them," said Oxburgh

"But jatropha grows on marginal or degraded land where not much else will really grow.

High oil prices and concerns about global warming have fueled demand for renewable energy sources such as biofuels

Jatropha curcas, one of 175 different plants, shrubs, and trees in the Jatropha family, produces seeds containing up to 40 percent oil

The advantage of drought-resistant jatropha is that it can be grown primarily on nonagricultural or marginal land in Africa and

the plant grows along the rail line between Mumbai and Delhi