To Make Ethanol, Start with Sawdust, Chocolate and Used Diapers

Last Updated Jul 20, 2009 10:36 AM EDT

The morning email contained a rather calculated solicitation: a "Russian scientist" and a University of Iowa student had cooked up a fungus that translated into inexpensive cellulosic ethanol--mandated by the federal government as part of the Energy Independence and Security Act of 2007. What's more, 21 billion gallons of the 36 billion gallons mandated had to be "advanced biofuels." The secret was ordinary sugar, and this one company had a lock on it.

It sounded like they were, literally, selling snake oil, since sugar is the key to many, many companies' efforts to create cellulosic fuels from biomass.

Still, there's something to this sugar thing, and biofuels are definitely on the ascendancy, and the federal renewable fuels mandates are indeed a driver (the email got that part right). Lately I've been assailed with legitimate processes to make biofuels from the most unlikely substances: coffee grounds, sawdust, used diapers, urine, turkey guts, methane from the rear ends of cows and more. I've even heard of engines that will burn just about any liquid fuel. Here's a brief rundown of the field, condensed from a longer piece I wrote on the subject:

Chocolate. At the University of Warwick in England, scientists are using waste Cadbury's chocolate to make biodiesel powering a Formula 3 race car (with a steering wheel partly fabricated from carrots).

Used diapers. They were already reclaiming the paper pulp from diapers, but now the poop itself is going into the pot at a Quebec-based company that plans to take in 180 million diapers annually and produce 11 million liters of diesel fuel from it. The great thing about diapers is they collect the raw material (a/k/a "feedstock") in a nice package that can be easily transported--and kept out of the landfill.

Sawdust. Both university and commercial researchers are racing to produce standard fuels--gasoline, diesel and jet fuel--from biomass in a pyrolysis process (high heat without oxygen). Many cellulose-rich plants work, but University of Massachusetts scientists are working with sawdust because it's cheap and readily available.

Turkey guts. Again, this is a readily available waste product, and a Missouri plant has already opened, producing a fuel oil that can be further refined for America's waiting gas tanks. Unfortunately, the Changing World Technologies plant has had both production difficulties and complaints about the smell--but the process definitely works.

Cow power. Emissions from the livestock industry result in 18 percent of the world's global warming gas, says the United Nations. It's about time the cows gave back, and now they are in the form of methane to run generators and produce electricity. "Cow power" is sweeping dairy states like Vermont.

Urine. This one's new to me, but Ohio University researchers say that within six months urine powered cars "could be available." The byproduct in this case is hydrogen, an energy carrier that many see powering the transportation of the future. Again, the fuel factory could be cows: "One cow can provide enough energy to supply hot water for 19 houses, said Professor Geraldine Botte. "Soldiers in the field could carry their own fuel."

Coffee grounds. This unwanted waste product contains 10 to 15 percent oil, and could produce as much as 340 million gallons of fuel annually from the world's 15 billion pounds of annual coffee consumption. Scientists at the University of Nevada, Reno say that coffee can become fuel in a simple two-step process. Could Starbucks one day rival Exxon?

Flickr/Skinnyde photo