Economist: MAKE something people want to buy at a price they can afford. Hardly a revolutionary business strategy, but one that the American biofuels industry has, to date, eschewed. Now a new wave of companies think that they have the technology to change the game and make unsubsidised profits. If they can do so reliably, and on a large scale, biofuels may have a lot more success in freeing the world from fossil fuels than they have had until now. The original 1970s appeal of biofuels was the opportunity…