Microbial Electrosynthesis: Wiring Microbes to the Sun for Chemical and Fuel Production
- Nevin, K.P., T.L. Woodard, A.E. Franks, Z.M. Summers, and D.R. Lovley. 2010. Microbial electrosynthesis: feeding microbes electricity to convert carbon dioxide and water to multicarbon extracellular organic compounds. mBio 1(2)
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Microbial Electrosynthesis: Converting Carbon Dioxide and Water to Fuels and Chemicals
ME Technology: What is it?
Microbial electrosynthesis (ME) technology represents a new form of photosynthesis that uses renewable solar energy to convert carbon dioxide emissions to fuels and other useful products. Like plant photosynthesis, carbon dioxide and water are combined to produce organic compounds with the release of oxygen. However, ME technology is much more efficient. One reason for this is that the photovolatics (i.e. solar panels) that are used in ME technology harvest solar energy 100 times more effectively than plants.
The ME technology does not require cultivatable land and avoids the environmental degradation associated with intensive agricultural processes. Furthermore, ME technology produces organic products directly. This is much more efficient than plant-based approaches, such as fermentation to ethanol, which require additional energy inputs and produce extensive wastes in order to generate a product.
Why is ME Technology Important?
Sunlight is the most abundant source of renewable energy. Photovoltaic technology for converting solar energy into electricity is well developed and can harvest solar energy much more effectively than photosynthesis. However, photovolatics only produce electricity when the sun is shining. Storing electricity is difficult. ME technology can convert the electrical energy produce from solar panels into chemical energy in the form of fuels and chemicals. Fuels and chemicals are easily stored and can be distributed through existing infrastructure on an as needed basis.
How does ME Technology Work?
ME technology is based on the discovery made at the University of Massachusetts that some microorganisms can feed on electricity. The microorganisms live on the surface of electrodes, using the electrons released from the electrode as their food source. The microorganisms use carbon dioxide in the same way that humans use oxygen. The microorganisms "breathe in" in the carbon dioxide and convert it to organic compounds that the microorganisms then "breathe out". Acetic acid (i.e. vinegar) is the simplest example of a ME product, but other products, such as the fuel ethanol, have also already been produced. Short-term product targets include the gasoline substitute butanol and butanediol, used to produce plastics.
UMASS Wins Grant to Convert Carbon Dioxide Emissions to Fuels
[April 29, 2010]
Vice President Joe Biden announced today that the Department of Energy has awarded the University of Massachusetts-Amherst a research grant to develop a new technology to convert carbon dioxide into transportation fuels. The technology is based on the UMASS discovery that some microorganisms can feed on electrons delivered with electrodes. The electrical energy powers the microbes to "breathe in" carbon dioxide and "exhale" fuels and other useful products. Any source of electricity will suffice, but the technology is primarily designed to be coupled with solar panels, to power the microbes with renewable solar energy. The technology, known as microbial electrosynthesis, is expected to produce fuels and other chemicals that can be used within the existing infrastructure, without the environmental risks associated with petroleum or intensive farming of biofuel crops.
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Microbial electrosynthesis apparatus
Microbial electrosynthesis apparatus
Geobacter on electrode
Microbial electrosynthesis apparatus
Microbial electrosynthesis apparatus with UMASS investigator Kelly Nevin
Microbial electrosynthesis apparatus with UMASS investigator Kelly Nevin
Video
Professor Derek Lovley describes microbial electrosynthesis in this excerpt from "New uses for microorganisms".
Produced by UMass News/Media Relations Office; © 2009 University of Massachusetts
Basic Science with an Applied Product
About Geobacter
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,
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.3600x.jpg)
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.
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