When police bring the traffic to an abrupt halt in Raipur, capital of the remote Indian state of Chhattisgarh, drivers know what to expect next. Soon, flashing red lights atop speeding government vehicles come into view. Raman Singh, Chhattisgarh's chief minister, is passing through. Government motorcades are a common sight in Indian capitals. But what is different about this one is that all of Chhattisgarh's official vehicles, including the chief minister's Tata Safari jeep, are run on oil from the wrinkled black nut of a shrub-like tree called jatropha. Unlike biofuels made from crops such as soybeans and maize, jatropha (below) is inedible, grows on non-arable land and needs little water or care. "It has good potential, no doubt about it,' says Suhas Wani, principal scientist at the International Crops Research Institute for the Semi-Arid Tropics, near Hyderabad. Chhattisgarh is well positioned to become the country's biodiesel hub. It's fleet of 40 or so jatropha-powered cars reflects the state's push to develop alternative energy sources that also include solar, wind, small hydroelectric, biomass and industrial waste. India, which imports more than 70 per cent of its oil and gas, is trying to launch one of the world's biggest jatropha biofuel projects in order to bolster energy security. The country's Ministry of Rural Development has proposed spending $375 million (