In labs across South Carolina, scientists are teaming up to find ways to use microbes to create a new fuel to replace gasoline in cars and light trucks.
The key components are as novel as they are unlikely: living microbes that, when stimulated with electricity, will turn carbon dioxide — the plentiful compound best known as a destructive greenhouse gas — into an alcohol-based fuel.
"This research will be focused mostly on the bench scale, and will provide insight into how to do it at the commercial production level," said Stephen Creager, chairman of Clemson University's chemistry department. "As with other biofuels, a scalable, reliable process, along with production costs and volumes will be the issues."
The research is part of a U.S. Department of Energy (DOE) initiative that involves scientists at South Carolina's research universities.
Clemson's contributors — electrochemist Creager and microbiologist Mike Henson, a research associate professor in the biological sciences department — are trying to determine the best mix of microorganisms and chemical reactions to ramp up the fuel-making process. Researchers at the Medical University of South Carolina and the University of South Carolina are working on other pieces of the puzzle.
"This is a remarkable collaboration, leveraging the expertise and creativity of scientists from our research universities," Henson said. "Among the projects approved, ours does something unique by having all the principal investigators in one state: South Carolina."
Ethanol and butanol
The research could lead to an industrial process to produce light motor fuels that could replace gasoline without having to modify engines.
Ethanol is currently being used as such a fuel. However, the scientists have higher hopes for butanol, which they say could meet the needs of virtually all current passenger and other light vehicles. What's more, it could provide a dramatic boost for the economies of oil-dependent nations and reduce anxiety about fuel supplies from abroad.
Has significant advantages
Butanol has significant advantages over ethanol. For one, it has a much higher "energy density" than the weaker ethanol: Butanol has about 90 percent of the energy content of gasoline, compared with about 60 percent for ethanol.
Unlike ethanol, butanol does not mix with water, which means it will not corrode steel pipes and steel storage tanks, the infrastructure of the existing fuel-transportation network. Butanol also is compatible with aluminum vehicular fuel systems and does not need to be mixed with fossil fuels to spark ignition.
It is, the scientists say, a "drop-in" replacement for gasoline.
To make butanol, the researchers intend to use an electrochemical process to release electrons that will be consumed by microbes to convert carbon dioxide into butanol. The result of the process is the alcohol fuel.
Creager, the electrochemist, is researching chemical reactions that generate, store and utilize electricity. Some chemical reactions create electricity spontaneously — the way batteries work. Others need to be given a "push" to do so. The push is a catalyst, which is a substance that starts or speeds up a process. The bacteria will act as a biocatalyst in this process.
Creager's work will focus on creating an environment in which the microbes can live and access the electrons from the electrochemical source.
Finding and optimizing the microorganisms that will do the work of converting carbon dioxide to butanol molecules using the electrons is the research challenge for the microbiologist. Henson must identify a microbe or microbes that not only produce the alcohol but also can thrive in an electrochemical environment. He has some candidates but more work must be done to find the best choice.
Sean Norman, an assistant professor and microbial ecologist at the University of South Carolina, will analyze the microbe's genes. His research aims to identify and optimize the genetic pathways that allow the microbes to produce biofuel and thrive — to create, enhance and grow a synthetic "microbiofuel-maker."
Creager and Harold May, a Medical University of South Carolina professor and the principal investigator for the project, teamed up on a similar experimental idea several years ago. When the Department of Energy recently sought groundbreaking biofuel research, the four scientists from the three universities applied for a grant.
"The idea is groundbreaking yet practical. We just need to figure out which pieces are the right ones and how they will fit together," Creager said.
The three-year, $2.3 million research project, begun last year, is one of 13 such projects funded by the energy departments' Advanced Research Projects Agency-Energy (ARPA-E) to explore alternate ways to make fuel out of existing and synthetic organisms.
Launched by U.S. Secretary of Energy Stephen Chu, the grants are to spur leap-taking research that would optimize organisms to make energy-rich liquid fuels. The goal is develop fuels that "could be 10 times more efficient" than the existing biofuel (ethanol and biodiesel) technologies, according to ARPA-E's website.
South Carolina's project, "Electroalcoholgenesis: Bioelectrochemical Reduction of CO2 to Butanol," is to "develop an electrolysis cell that will employ microbes that can use electricity to convert carbon dioxide into ethanol and butanol."
The MUSC, USC and Clemson researchers are presenting a progress report on their research at the ARPA-E annual summit meeting in Washington, D.C., this month.