Turning Waste into Energy

From Joel Makower at the Two Steps Forward blog:

Turning waste into fuel. Seems like one of those too-good-to-be-true concepts — like cars that run on water. But it’s far from farfetched.

An Agricultural Research Service soil scientist at the North Central Soil Conservation Research Laboratory in Morris, Minn., has teamed up with an inventor of a patent-pending process to turn agricultural biomass — wastes like peanut shells — into hydrogen fuel and charcoal fertilizer. Volatiles and steam released by charring biomass produce hydrogen. The charring turns the biomass into charcoal pieces. This charcoal becomes a nitrogen-enriched fertilizer with the addition of ammonia formed by combining a third of the hydrogen with nitrogen. The remaining hydrogen can be sold as fuel, both for a hydrogen-based, clean diesel and to run fuel cells.

Researchers from the University of Wisconsin at Madison have found a way to use the carbon monoxide — a waste gas — to produce more energy in a reaction that can take place at room temperature. The method could eventually be used in portable systems that use renewable fuel produced from plant matter, said James Dumesic, a U of W professor of chemical and biological engineering. The process could also be used to treat wastewater and contaminated gas streams, he said.

Dr. Bruce Rittmann, a professor at Northwestern University, has posed an answer to the following quandary: On a two-year trip to Mars, according to one estimate, a crew of six humans will generate more than six tons of solid organic waste — much of it feces. So what do you do with all that?

According to Space.com, what Rittmann proposes to do is to harness bacteria — specifically, a member of the Geobacteraceae family that feeds on, and can decompose, organic material. Geobacter microbes were first discovered in the muck of the Potomac River in 1987; they like to live in places where there’s no oxygen and plenty of iron. They also have the unexpected ability to move electrons into metal. That means that under the right conditions, Geobacter microbes can both process waste and generate electricity.

This isn’t just pie-in-the-sky stuff. In Washington state, King County’s Wastewater Treatment Division, FuelCell Energy Inc., and the U.S. EPA are jointly sponsoring the world’s largest demonstration project of a fuel cell using digester gas — a.k.a. methane — as fuel. Two King County wastewater treatment plants now use gas generated during treatment operations, which is sold to two local utilities.

What’s going on here? While a typical fuel cell runs on hydrogen, these microbial fuel cells rely on bacteria to metabolize food, releasing electrons that yield a steady electrical current. Other microbial fuel cells have used fuels like glucose or ethanol. In the case of King County, the fuel was skimmed from the settling pond of a wastewater treatment plant.

The potential, suffice to say, is tremendous. Why drill, dig, and mine "virgin" energy sources when there is endless potential to capture the detritus of human and industrial activity and transform it into electricity and usable fuels?

Link: The Alchemy of Turning Waste into Energy