But building a system to turn any carbon into ethanol is one thing; finding a steady diet for such an omnivore is another. Take trash, for instance. Many environmentalists are eager to harvest fuel from bald tires and junk plastic. Yet Range Fuels’ fancy new ethanol plant, which will eventually pump out 100 million gallons of fuel a year, will feed mostly on wood chips. “What’s nice about wood chips is that they’re pretty uniform. You’re not sorting out hearing aid batteries from it,” says Samir Kaul, a principal at Khosla Ventures, a venture capital firm started by Sun Microsystems founder Vinod Khosla. Khosla Ventures is financing at least three ethanol producers, including both Range Fuels and Coskata, and so is sensitive to practical issues. “Garbage is risky,” Kaul says, “and when you scale a technology for the first time, you don’t want to add risk where you don’t have to.”
Surprisingly, the other problem with trash is that there may not be enough of it. Coskata estimates that municipal solid waste is less than 10 percent of all the available biomass—too little, perhaps, to make developing a sorting process worthwhile, at least at the outset.
Other sources of waste are more promising. The government biomass study that came up with 1.4 billion tons of annually available biomass identified farming and timber residues (cornstalks and the unusable parts of logged trees) as the source for nearly half of the nation’s bioenergy. The trick will be cheaply delivering these leftovers to the ethanol plant.
Range Fuels initially hoped to feed its refinery with leaves and small limbs that the timber industry cannot process. The Georgia Forestry Commission reports that each year loggers leave behind some 8 million tons of waste wood, including too-small living trees, within a 75-mile radius of the new refinery—enough for four of Range Fuels’ plants. But getting that material to the refinery has proved difficult. “The timber industries are really not set up to do that,” says Range Fuels’ Mandich.
Nobody has yet figured out how to compact forest leftovers for transport. “Have you ever tried to move your leaves in the fall?” asks Richard Hess, a scientist studying the problem at Idaho National Laboratory. “You fill up this garbage sack and it doesn’t weigh anything. That’s the problem. It takes a lot of energy to move air.” Still, Hess expects optimized handling systems will be ready by 2012, meeting the government’s goal and in time for a wave of new refineries. “We’re rich in opportunities to make fairly epic gains,” he says. Until then Range Fuels will source its wood chips from whole trees—not a waste product at all, but a commodity used to make paper pulp.
It might not be long before the ethanol companies are paying to get more biomass waste headed into their plants. According to Richard Bain, a researcher at NREL, the estimated cost of producing a gallon of ethanol stands at $2.10 today. By 2012 this should fall to $1.33—at least for those companies using steam to turn biomass into syngas (several firms, he says, have developed this technology). At the same time, the steep price of gasoline—and corn—means that next-generation ethanol can be profitable even if its price doesn’t reach what Khosla Ventures’ Kaul calls the “holy grail” of $1 a gallon. Freed from the bad rap of corn ethanol, biofuel-powered cars could then drive us toward a better future.
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