Bug Juice 

Could termite guts hold the key to the world's energy problems? Don't laugh.

Here are a few numbers to keep in mind regarding the future of hydrogen-powered cars:

Tailpipe emissions: zero.

Dependency on foreign oil: zero.

Number of termites crawling the planet: One hundred quadrillion. That's a one followed by seventeen zeros.

Granted, not many people are hip to the termite part of the equation yet. And most of those who are can be found in Walnut Creek working at the Joint Genome Institute, a branch of the federal Department of Energy that is looking for alternative fuel sources in some very unexpected places -- like a termite's gut.

Even groups as disparate as environmentalists and auto industry execs can agree that hydrogen is a promising alternative to gasoline. Engines powered by the stuff are twice as efficient as their gas or diesel counterparts, and emit only distilled water -- which means no smog, no refineries, no $3-a-gallon gas. The public is hungry for clean vehicles, most auto manufacturers are developing prototype fuel-cell cars, and California recently ponied up $54 million to build hydrogen fueling stations statewide.

So what's the holdup? Sure, there are still significant technology issues, and fuel-cell vehicles are years from commercial viability, but perhaps the most profound problem lies on the supply side: Nobody knows where all this fuel is going to come from.

You can't just tap into a pre-existing supply of hydrogen the way you drill for oil. It has to be manufactured, which is typically done by stripping hydrogen molecules from water or natural gas using electricity. But hydrogen produced this way is only as environment-friendly as the electricity source used to make it. So-called "brown" hydrogen is indirectly derived from the big three -- coal, oil, and natural gas -- with greenhouse gases and other pollutants as byproducts, while "green" hydrogen requires electricity from sources such as wind and solar, which are renewable but represent a minuscule fraction of US electricity production. For years, energy experts have been searching for the holy grail: a way to make hydrogen that is cheap, nonpolluting, and scalable to the mass market.

Philip Hugenholtz, head of the microbial ecology program at the Joint Genome Institute, thinks nature may have the answer. Many microbes make hydrogen, after all, sometimes in vast quantities. His team believes the most promising candidates are bacteria that live in a termite's gut, quietly breaking down plant matter and releasing hydrogen as a byproduct. These microbes make termites the most efficient hydrogen producers on the planet: From a single sheet of printer paper, a termite can produce two liters of the valuable gas. "We don't know how they do it, but we know they do it well," Hugenholtz muses.

And there's the rub -- until recently these bugs within a bug have received scant attention from scientists. We know the bacteria are a motley crew consisting of at least six different lineages more distantly related to each other than human beings are to trees, but little is known about how they operate. Of at least 200 different microbial species living in the termite's nether regions, 190 are pretty much terra incognita. Indeed, when the JGI team sequenced microbial DNA from the first test batch of termites they found in Costa Rica, they were elated to discover as-yet-uncharacterized species of bacteria.

The trick is to figure out which bacteria make hydrogen, and which enzymes they use to do it. With this information, Hugenholtz says, you could replicate those enzymes in mass quantities to produce hydrogen on a commercial scale. What's more, you could fuel the process with agricultural and industrial waste -- lumber-mill tailings, scrap cardboard, and the endless tons of corn husks and sugarcane stalks that are burned or discarded because they're too tough for farm animals to eat. "It's kind of recycling, making use of what's already there," says Falk Warnecke, a JGI microbiologist working on the project.

This line of inquiry excites energy experts who think we'd be better off farming our energy resources than drilling for them. "It's going to be in the long run a dirt-cheap way to make hydrogen in a very easy-to-do manner," says physicist Daniel Kammen, director of the Renewable and Appropriate Energy Laboratory at UC Berkeley. "I think that's exactly where hydrogen could and should come from."


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