On one side of a factory here, workers dump 500-pound sacks of pine chips into a hopper. Deep inside the plant, an 8,000-degree blow torch roars like a jet engine as the chips are processed. At the far end, the workers turn a tap and out pours ethanol, ready for use as a motor fuel. The facility, built by a company called Coskata, is not quite proof that a new era is at hand for American transportation fuels. But with the company claiming it will be able to convert wood waste into biofuel for about $1 a gallon, the plant suggests that day may be drawing nearer.