Post by Swamp Gas on Nov 15, 2007 12:55:56 GMT -5
www.wired.com/cars/energy/news/2007/11/hydrogen_bacteria
New Method Uses Bacteria to Generate Hydrogen Gas
By Chuck Squatriglia Email 11.12.07 | 7:00 PM
Researchers at Penn State University say they've developed a way to use bacteria to extract hydrogen from almost any biodegradable organic substance, from grass clippings to wastewater.
Hydrogen is often touted as a virtually limitless source of clean energy, but its ecological benefits have been minimal because it is often produced using natural gas in a process that releases carbon dioxide -- a problem the new method seems to solve.
The discovery, published Monday in Proceedings of the National Academy of Sciences, holds great promise for advancing hydrogen as a viable sustainable fuel because, the researchers say, it uses existing technology and can be put to use immediately.
"It's crossed the line from a science-fair project to feasible technology," said Bruce Logan, a professor of environmental engineering who led the research. "You can do it from any renewable organic matter."
Most of the major automakers are at least experimenting with hydrogen fuel cell vehicles, which use hydrogen and oxygen to create electricity that powers the car. Several have developed test fleets, and 107 fuel cell vehicles are on California roads, according to the California Fuel Cell Partnership. But fuel cells remain frightfully expensive and aren't very durable, two issues Daimler and Ford hope to address through a joint venture to make the technology more viable.
Although widespread adoption of hydrogen won't happen for at least a generation, if it happens at all, Logan says his discovery offers immediate environmental benefits because hydrogen can be mixed with compressed natural gas to produce fuel that pollutes less than natural gas alone.
Compressed natural gas is often used in and fleet vehicles. It also is used in some cars, including the Honda Civic GX. BMW produces the 750hL, a "flex fuel" vehicle that can run on gasoline or hydrogen. A relatively easy means of producing hydrogen could prompt further development of hydrogen and CNG vehicles.
"You can take existing technology and make this switch," said Logan, who hopes to patent his discovery.
Logan and his research assistant Shaoan Cheng's method uses bacteria called exoelectrogens to break down acetic acid -- produced by fermenting cellulose, glucose or other biodegradable organic matter -- in a microbial electrolysis cell to create hydrogen.
When bacteria consume the acid, electrons are transferred to a graphite anode. The bacteria also release protons -- hydrogen atoms stripped of electrons -- that are held in solution. As electrons are transferred to a platinum cathode, they combine with the protons and generate 0.3 volts of electricity. Adding another 0.2 volts creates hydrogen gas.
Logan said microbial electrolysis cells are easy to make, and the bacteria needed for the process are plentiful. Although one could, in theory, build such a cell for home use, Logan said it would be far more practical on a commercial scale.
Hydrogen is the most abundant element in the universe, but it rarely appears alone and must be extracted from other substances. The cheapest and most common method is steam reforming, where natural gas and steam create a chemical reaction that yields hydrogen and carbon dioxide. This method produces almost half the hydrogen available today.
Greener methods use wind, solar and other sustainable energy to generate electricity for electrolysis, which divides water into hydrogen and oxygen. But it requires a lot of water and energy, making it relatively inefficient, and accounts for just 4 percent of all hydrogen produced.
Finding more sustainable ways of producing hydrogen would go a long way toward making it a viable form of energy, and is the subject of a growing body of research. Hydrogen advocates said Logan's discovery places sustainable hydrogen within reach.
"There's a great deal of focus on this from the academic worlds, and the research they're doing at Penn State will help prove that that hydrogen is a viable alternative," said Roy Kim, a spokesman for the California Fuel Cell Partnership, a consortium of 34 automakers, fuel cell researchers, transit agencies and other organizations.
"If we can develop a method that can be mass-marketed to produce enough fuel," Kim said, "it would be a great addition to the diversity of feedstock that we can use to produce hydrogen."
The researchers noted that the method produces up to 82 percent more energy than the electricity and biomass needed to produce it.
That, Logan says, makes hydrogen far more attractive than corn-based ethanol, which produces at best 30 percent more energy than is required to produce it. Cellulosic ethanol promises to make the process far more efficient, but it remains at least a decade away from viability.
New Method Uses Bacteria to Generate Hydrogen Gas
By Chuck Squatriglia Email 11.12.07 | 7:00 PM
Researchers at Penn State University say they've developed a way to use bacteria to extract hydrogen from almost any biodegradable organic substance, from grass clippings to wastewater.
Hydrogen is often touted as a virtually limitless source of clean energy, but its ecological benefits have been minimal because it is often produced using natural gas in a process that releases carbon dioxide -- a problem the new method seems to solve.
The discovery, published Monday in Proceedings of the National Academy of Sciences, holds great promise for advancing hydrogen as a viable sustainable fuel because, the researchers say, it uses existing technology and can be put to use immediately.
"It's crossed the line from a science-fair project to feasible technology," said Bruce Logan, a professor of environmental engineering who led the research. "You can do it from any renewable organic matter."
Most of the major automakers are at least experimenting with hydrogen fuel cell vehicles, which use hydrogen and oxygen to create electricity that powers the car. Several have developed test fleets, and 107 fuel cell vehicles are on California roads, according to the California Fuel Cell Partnership. But fuel cells remain frightfully expensive and aren't very durable, two issues Daimler and Ford hope to address through a joint venture to make the technology more viable.
Although widespread adoption of hydrogen won't happen for at least a generation, if it happens at all, Logan says his discovery offers immediate environmental benefits because hydrogen can be mixed with compressed natural gas to produce fuel that pollutes less than natural gas alone.
Compressed natural gas is often used in and fleet vehicles. It also is used in some cars, including the Honda Civic GX. BMW produces the 750hL, a "flex fuel" vehicle that can run on gasoline or hydrogen. A relatively easy means of producing hydrogen could prompt further development of hydrogen and CNG vehicles.
"You can take existing technology and make this switch," said Logan, who hopes to patent his discovery.
Logan and his research assistant Shaoan Cheng's method uses bacteria called exoelectrogens to break down acetic acid -- produced by fermenting cellulose, glucose or other biodegradable organic matter -- in a microbial electrolysis cell to create hydrogen.
When bacteria consume the acid, electrons are transferred to a graphite anode. The bacteria also release protons -- hydrogen atoms stripped of electrons -- that are held in solution. As electrons are transferred to a platinum cathode, they combine with the protons and generate 0.3 volts of electricity. Adding another 0.2 volts creates hydrogen gas.
Logan said microbial electrolysis cells are easy to make, and the bacteria needed for the process are plentiful. Although one could, in theory, build such a cell for home use, Logan said it would be far more practical on a commercial scale.
Hydrogen is the most abundant element in the universe, but it rarely appears alone and must be extracted from other substances. The cheapest and most common method is steam reforming, where natural gas and steam create a chemical reaction that yields hydrogen and carbon dioxide. This method produces almost half the hydrogen available today.
Greener methods use wind, solar and other sustainable energy to generate electricity for electrolysis, which divides water into hydrogen and oxygen. But it requires a lot of water and energy, making it relatively inefficient, and accounts for just 4 percent of all hydrogen produced.
Finding more sustainable ways of producing hydrogen would go a long way toward making it a viable form of energy, and is the subject of a growing body of research. Hydrogen advocates said Logan's discovery places sustainable hydrogen within reach.
"There's a great deal of focus on this from the academic worlds, and the research they're doing at Penn State will help prove that that hydrogen is a viable alternative," said Roy Kim, a spokesman for the California Fuel Cell Partnership, a consortium of 34 automakers, fuel cell researchers, transit agencies and other organizations.
"If we can develop a method that can be mass-marketed to produce enough fuel," Kim said, "it would be a great addition to the diversity of feedstock that we can use to produce hydrogen."
The researchers noted that the method produces up to 82 percent more energy than the electricity and biomass needed to produce it.
That, Logan says, makes hydrogen far more attractive than corn-based ethanol, which produces at best 30 percent more energy than is required to produce it. Cellulosic ethanol promises to make the process far more efficient, but it remains at least a decade away from viability.