How can we create effective energy and fuels that are both efficient and better for the environment?

Thanks to the Sustainable Energy Education and Research Center (SEERC), UT is discovering new answers to that very question and quickly becoming a world leader in green energy research.

Directed by Bamin Khomami, professor and head of the Department of Chemical and Biomolecular Engineering, SEERC was established to educate the next generation of industry and academic leaders by bringing together scientists and engineers from foundational disciplines and by forging partnerships with key organizations.

“The idea of SEERC is to build the intellectual and physical infrastructure to train future leaders of sustainable energy research,” Khomami says. This mission, coupled with strategic investments of resources to fund seed research and educational projects, will further strengthen existing areas of research and promote new directions.

“When I started thinking about developing a research center, it became very clear that sustainable energy was going to be the most important challenge facing the human race in the twenty-first century,” Khomami says. “With its close proximity to ORNL, it was obvious that UT needed an umbrella organization to foster all renewable energy research on campus.”

Khomami first identified faculty involved in sustainable energy research on campus and developed a plan for umbrella hires in strategic areas. Once a core group was assembled, SEERC’s three “research thrusts”—advanced materials, biofuels, and energy conversion and storage—were created.

Advanced Materials

One of the most pressing needs for a sustainable future is the development of clean energy alternatives to current finite resources such as coal and oil. Because of their ability to transform energy from the sun into electricity, photovoltaic devices are perhaps the most attractive alternative sources.

Organic photovoltaics are one of the most promising new technologies available for this conversion. An organic photovoltaic cell uses conductive organic polymers—or small, conductive organic molecules—for light absorption and charge transport.

In SEERC’s advanced materials research thrust, chemistry professor Mark Dadmun and his colleagues are working to improve the function of organic photovoltaics by better understanding the structures of the materials involved. Since organic photovoltaics are based on mixtures of two materials, how well these materials mix and the structure they form when they mix is critical to turning sunlight into energy.

According to Dadmun, most of the research in this area has focused on the function of the material and how it worked.

“Very few scientists were looking at the structure of these organic photovoltaics,” Dadmun says. “In order to improve function, we must understand the structure.”

By controlling and characterizing the structure, Dadmun and his team create materials in the hopes of discovering the characteristics that provide optimal energy production. They record the characteristics and correlate those to the function of the material, determined by measuring its photovoltaic efficiency. Computational studies also provide insight into the structure of the material.

“If we can correlate the structure of a material to its function, we will be able to develop better ways to create energy from the sun,” he says.

Although there are few organic photovoltaics on the market, they have a bright future. As with any new technology, there are engineering obstacles to overcome before they can be as efficient as silicon cells. Dadmun is confident that as these engineering problems are addressed, the use of organic photovoltaics will help ease our dependence on finite resources for energy production.

Biofuels

SEERC’s biofuels research thrust is lead by Paul Frymier, professor in the Department of Chemical and Biomolecular Engineering.

Along with colleague Eric Boder, Frymier is developing methods to form photovoltaic devices and systems using a biological process. Some bacteria exhibit a property known as the “photoelectric effect,” which causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.

Frymier’s research focuses on using cyanobacteria, a phylum of bacteria that obtains its energy through photosynthesis, in order to develop an electrical current. The key is combining proteins that capture energy with enzymes that attach them to surfaces.

“The photosystem is one big protein that is shaped like a lampshade,” Frymier explains. “Its primary function is to move an electron. When it absorbs a photon, it separates the positive and negative parts of the protein’s reaction center. This moves the electron. The bigger the separation, the further the electron moves. Eventually, the electron can move away from the protein altogether. Left with a hole, another electron moves in its place.”

The constant movement of electrons creates an electric circuit, a system that has potential for sustainable energy applications. Today’s solar cells generate current by inorganic molecules called “dopants” that are incorporated into silicon. The energy system Frymier is developing generates energy with proteins that bacteria make naturally. The idea is to grow bacteria on an inexpensive source like sugar, harvest the proteins, and use them in the photosystem.

According to Frymier, photosystem proteins can be easily attached to a solid surface. The trick, however, is how to get them aligned properly.

“Our method is working to get them all pointed in the same direction, so the electrons move in the same direction and generate more current,” he says.

Frymier believes cyanobacteria are a good source for the desired proteins because the genetics are very well known and they grow quickly. Combining his research with the tools of molecular biology, new proteins can be generated that can be easily attached to surfaces or given improved properties like faster rates or higher stability.

“This is a completely different way of making solar cells that could potentially reduce the cost,” Frymier says. “Bacteria are very efficient in transferring the energy of a photon to charge separation—almost 100 percent efficient—giving it the potential to be more efficient than any other process.”

Also, cyanobacteria do not compete with land use for food production. When bacteria grow in the lab, the bulk of what researchers feed it is another carbon source, which could be atmospheric carbon dioxide.

Energy Conversion and Storage

Stephen Paddison, professor in the Department of Chemical and Biomolecular Engineering, leads SEERC’s third research thrust: energy conversion and storage.

Fuel cells have emerged as a promising alternative to power conversion devices like internal combustion engines because they create electrical energy rather than thermal energy, which is linked to global climate change.

The technology known as proton exchange membrane (PEM) fuel cells, also called solid polymer fuel cells, could enable the mass production of affordable hydrogen-powered fuel cell vehicles.

A PEM fuel cell creates electrical energy by transforming the chemical energy released during the electrochemical reaction of hydrogen and oxygen. A stream of hydrogen is delivered to the membrane electrode assembly where an electric current acts as a catalyst, creating a chemical reaction that splits the hydrogen into protons and electrons.

“Our research addresses the functionality of a PEM fuel cell and its limitations in transporting materials across its interface,” says Paddison. “Once we understand the limitations, we can dictate the transportation of the materials across interfaces.”

When applied, Paddison’s research will be valuable for the creation of a hydrogen-supply infrastructure to

support electric vehicles powered by hydrogen fuel cells.

Leading the Way to a Sustainable Future

While research is important to SEERC, the education component is equally vital. Recently, SEERC received an IGERT (Integrative Graduate Education and Research Traineeship) grant from the National Science Foundation to develop its flagship interdisciplinary training program, STAIR (Sustainable Technology through Advanced Interdisciplinary Research). Under the leadership of David Keffer, director of STAIR and professor of chemical and biomolecular engineering, a graduate certificate in sustainable energy was established at UT in 2010, offering courses based on case studies of energy projects.

In the last year, sixteen graduate students were taking part in IGERT, and ten undergraduates were conducting research for projects sponsored by SEERC.

“We have worked very hard to build synergy across all the thrusts of research,” Khomami says. “I wish to expand sustainability science, but it’s a bit more abstract than we are used to as scientists.”

Whether it’s organic photovoltaics, cyanobacteria, or PEM fuel cells that change the way we consume energy, research conducted at SEERC will continue to thrust UT into a leading role in the sustainable energy future.

Published online, Quest, November 3, 2011