Beef and trains. Two All-American favorites. But what if they could somehow be combined? Well, Amtrak is testing a new train and it is powered by beef-based biofuel. Is this the most American form of transportation ever?

CAMBRIDGE, MASS. — At MIT's EmTech conference, venture capitalist Vinod Khosla made a shocking assertion: Electric cars are irrelevant. Unless some unlikely breakthrough in battery technology comes about, they will never take enough of the market to matter. This is a financially convenient argument for Khosla to make: He has invested heavily in biofuels startups. But he raises a point few in the privileged West think about: Will the rising middle classes of China and India buy a $25,000 Prius, or a $2,500 Tata Nano?Make no mistake: Khosla intends to overturn oil-based transportation, and make a bundle while doing so. He is a skeptic of corn-based ethanol, but favors biofuels made from cheaply grown biomass like switchgrass. But he also thinks combustion engines can be improved to reach 100 miles per gallon — a "diesel Prius," he calls. Electric cars? Too burdened with heavy batteries, too costly to ever make up a large portion of our transport. Oh, but just in case he's wrong, he's got a couple of long-shot startups in his portfolio which could make them practical. (Photo by James Duncan Davidson/O'Reilly Media)