ERE'S a statistic that probably keeps China's leaders up at night: last year, China became more dependent on imported oil than the United States.  In the past decade, China has doubled the amount of oil it consumes but only marginally raised its own oil production. The result is that China now depends on foreign oil for 55pc of its needs.  and the future is not looking rosy. Even though 14m new cars are hitting the roads each year, only 5pc of Chinese are car owners.  There are over a billion people still to learn to drive, and even if you assume that only a minority of them will actually buy a car, China's thirst for petrol is looking ominous. We believe the number of cars on the road is going to nearly triple to 185m by 2020.  Electric cars are one solution, although Chinese companies have had the same difficulties with the technology that has troubled car companies in the West, and biofuels might be another.  In Brazil, ethanol is already providing over half of all motor fuel. In the US, it is powering almost 9pc of cars, up from 3pc in 2005. In fact, american petrol consumption has shrunk in that period by 121,000 barrels a day.  So far, however, ethanol has not been much used in China, which needs corn to feed people, not to convert into fuel. China is already a net importer of food and does not have any grain to spare. Grain consumption is rising by 2pc each year and there are questions over whether China will be able to keep meeting its domestic needs, as more and more grain-fed meat becomes part of the national diet. But what it does have is agricultural waste, almost a billion tons a year, most of which is currently burned.