Wednesday, November 12, 2008

Do-It-Yourself Microbiological fuel cells from dirt?

Basic Science with an Applied Product

Geobacter species are of interest because of their novel electron transfer capabilities, impact on the natural environment and their application to the bioremediation of contaminated environments and harvesting electricity from waste organic matter. The first Geobacter species (initially designated strain GS-15) was isolated from the Potomac River, just down stream from Washington D.C. in 1987. This organism, known as Geobacter metallireducens,

G. metallireducens [larger image]
© 2005 eye of science
was the first organism found to oxidize organic compounds to carbon dioxide with iron oxides as the electron acceptor. In other words, Geobacter metallireducens gains its energy by using iron oxides (a rust-like mineral) in the same way that humans use oxygen. As outlined in the publication links, Geobacter metallireducens and other Geobacter species that have subsequently been isolated provide a model for important iron transformations on modern earth and may explain geological phenomena, such as the massive accumulation of magnetite in ancient iron formations.

Geobacter species are also of interest because of their role in environmental restoration. For example, Geobacter species can destroy petroleum contaminants in polluted groundwater by oxidizing these compounds to harmless carbon dioxide. As understanding of the functioning of Geobacter species has improved it has been possible to use this information to modify environmental conditions in order to accelerate the rate of contaminant degradation. As outlined under the Bioremediation link, Geobacter species are also useful for removing radioactive metal contaminants from groundwater.

Geobacter species also have the ability to transfer electrons onto the surface of electrodes. As outlined under the Microbial Fuel Cell link, this has made it possible to design novel microbial fuel cells which can efficiently convert waste organic matter to electricity.

As outlined under the Genomics and Systems Biology link, the genomes of several Geobacter species have been sequenced and are being incorporated into a computer model that can predict Geobacter metabolism under different environmental conditions. This systems biology approach is greatly accelerating the understanding of how Geobacter species function and the optimization of bioremediation and energy harvesting applications.

[The following found at 12 Degrees of Freedom]

“You can just literally make energy from dirt”

Buckminster Fuller often talked about the difference between making money and making sense. Focusing exclusively on the former leads us down the road of over-consumption, environmental degradation, loss of biodiversity, social injustice and the global climate change.

Fuller practices something he called Comprehensive Anticipatory Design Science. Simply put he sought to solve problems of human life support by observing Nature and developing technologies based on her design strategy of "doing more with less".

Some of the best discoveries emerging from this process will not make the discoverer rich, but will make the world a better place for everyone.

Last year I was visiting the University of Massachusetts in Amherst and met Professor Derek Lovely. He was working with a bacteria known as Geobacter that possess electron transfer abilities capable of generating electricity in soils. I thought this was a very exciting concept, but had forgotten about it until I came across the following article. (GW)

For Africa, ‘Energy From Dirt’

START-UP companies around the world are looking at Africa — where 74 percent of the population lives without electricity — as a test market for new, off-the-grid lighting technologies.

Many of these efforts involve wind or solar power. But one group in Cambridge, Mass., is working to develop fuel cells made from the bacteria that occur in soil or waste.

“You can just literally make energy from dirt,” said Aviva Presser, a graduate student at the Harvard School of Engineering and Applied Sciences. “And there’s a lot of dirt in Africa.”

Ms. Presser is one of the founders of Lebone Solutions, which is being financed by a $200,000 World Bank grant and private investments. Lebone’s idea is a microbial fuel cell, a battery that makes a small amount of energy out of materials like manure, graphite cloth and soil, which are common to African households.

But Lebone — which means “light stick” in the Sotho language — does not just want to make the batteries and sell them to African consumers. The group hopes that eventually, as the technology becomes more refined, each household will be able to build a battery at a one-time cost of no more than $15.

“Africans are very, very creative,” said Hugo Van Vuuren, a Lebone founder. “It’s very entrepreneurial, just not in the way we traditionally define entrepreneurial.”

Mr. Van Vuuren, who is from Pretoria, South Africa, and who graduated from Harvard last year with a degree in economics, likened the simplicity of the battery to “the potato experiment that most of us did in high school class,” a two-step reaction that produces a simple charge.

But the bacteria in a microbial fuel cell produce electrons while doing what they naturally are supposed to do: metabolize organic waste, like dead leaves or grass or compost, for energy. The electrons then stick to an electrode, like a piece of graphite, and the chemical reaction that follows creates a small charge sufficient to power a small lamp or cellphone.

“It can be made by people with minimal training,” Ms. Presser said. “It doesn’t take a massive investment.”

The founders of the Lebone team were classmates at Harvard, and looking at sustainable lighting technologies for Africa was their class project. Last summer, they took the technology to Leguruki, a village in Tanzania, to see how the batteries work in households. For three hours each night, six families used batteries made of manure, graphite cloth and buckets, and a copper wire to conduct the current to a circuit board.

While in Leguruki, Mr. Van Vuuren said, the group learned as much about the people who used the batteries as the batteries themselves.

“People walk an hour or more a day to the local high schools to get their phones charged for two or three days,” he said, noting that the phones were sources of light as well as communication devices. The batteries are also used to power radios, Mr. Van Vuuren said, as important a medium of communication in Africa as the cellphone.

“Ideally, they would like to have a refrigerator,” Mr. Van Vuuren said. “But right now, their key need is a cellphone.”

Mr. Van Vuuren and several of his fellow Lebone researchers know the challenges of Africa personally, which he credits for the group’s commitment to focusing on Africa first.

“We are a group of Africans that have had the privilege of a first-rate education,” he said. “There are very few people who have insights into both. We lived through it.”

The group is expanding the refined prototypes into Namibia, where, over the next two years, it will examine how more easily available materials, like chicken wire, will create electricity. Mr. Van Vuuren said his group wanted to test the microbial cell batteries in African settings before bringing them to the American market.

Eventually, Lebone wants to create a new business model for energy distribution in Africa, helping to funnel fuel cells and other technologies tested in Africa to distributors there, rather than reducing developed technologies to meet African needs.

“If you work within those constraints, you can create something that works in the developed and developing world,” Mr. Van Vuuren said. “There’s no reason that people need to A: starve, or B: can’t read at night.”
Bug Powered Batteries interview w/ Derek Lovely, researcher.

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