FRANKFURT, Germany --- During a presentation at the auto show here, a leading Ford Motor Co. executive argued for the establishment of a biofuel accreditation system and for tax incentives to encourage greater biofuel use, Reuters reported. "Not all biofuels are good for the environment," said Richard Parry-Jones, Ford's head of global product development and chief technical officer. "There's a risk of a negative image emerging from the use of poor biofuels. We advocate the use of responsible biofuels, and we're developing a scheme for accredited fuels, like organic food." Parry-Jones pointed out that reliance on some biofuels can have unwanted consequences. "There have already been demonstrations in Mexico over the price of tortillas, the country's staple food, and in Indonesia and Malaysia rainforest is being felled for palm oil. Chopping forests down also causes the material on the floor to release CO2, further exacerbating the problems of irresponsible felling, and the food-chain can be affected too. So we need to isolate the biofuel negatives." Parry-Jones also backed more government incentives to spur greater use of responsible biofuels. "They're more expensive than fossil fuels, and likely to remain so," he said. "So we need a price incentive." Parry-Jones was hopeful about the potential supply of biofuel feedstock. "With second-generation cellulosic crops --- the fiber as well as the crop itself, can be fermented into alcohol --- you can use land not suitable for food," he explained. Parry-Jones cited switchgrass as an example of a crop that can be grown on poor-quality soil. He advocated the use of E40 on a widespread scale. "In the long-term the best way is not to have E85 or E70 for a dedicated fleet of vehicles, but to have a lower figure usable in nearly every car. This is more effective," he said.