Autumn 2009: Dynamic Forces
Secrets of the Swamp
A chemical reaction could spark the creation of clean energy
By Carol Clark
Can microbes that live in swamp mud help us produce green energy?
Chemistry Professor Brian Dyer is researching that possibility through his work at the intersection of chemistry, physics, and biology. Formerly with the Los Alamos National Laboratory in New Mexico, Dyer joined Emory this summer to help unite the University’s multidisciplinary research into renewable energy sources.
“The need for renewable energy is one of the key problems of our time,” Dyer says, “and Emory is well positioned to really make an impact in this area.”
Dyer uses laser spectroscopy to study how light can interact with materials. Early in his career, he began working with proteins that can do photochemistry, drawing his inspiration from natural photosynthesis.
“Ultimately, plants are taking light and storing it as chemical energy,” Dyer explains. “The elegance of some of these reactions is astounding. It’s an incredibly complex process, done with a series of proteins that are highly optimized for a specific function, such as light harvesting and water oxidation. The proteins are like tiny machines. A good analogy is an internal combustion engine, where you actually have integrated, working parts.”
In recent years, science and industry have begun seeking ways to develop systems of artificial photosynthesis to help solve the energy shortage and reduce carbon emissions. So far, humans’ attempts at tapping the sun’s power have fallen far short of Mother Nature’s.
While living in Los Alamos, located at 7,500 feet above sea level on the Pajarito Plateau, Dyer installed solar panels on his family’s house. “I wanted to understand the issues of solar energy at the practical level of a home owner,” he says. Even with 320 days a year of New Mexico sunshine, he found conventional solar panels to be inefficient and not cost effective.
“An even bigger problem is the batteries required to store the intermittent solar flux,” Dyer says. “Their storage capacity is limited, and their lifetime is short. They also contain hazardous chemicals, like lead and sulfuric acid.”
Dyer is focused on solving this solar energy storage problem. He wants to convert solar energy to fuel, using a particular protein to develop a photocatalyst for solar hydrogen production—which brings up the swamp bugs.
A type of anaerobic bacterium that lives deep in the mud of swamps, where there is little oxygen, survives by splitting water into hydrogen and oxygen. While humans need to use expensive systems to perform this process on a large scale, the bacteria do it naturally by generating the protein hydrogenase—the most efficient catalyst known for making hydrogen. By studying the biological system, Dyer hopes to find ways to adapt the microbial catalysis of hydrogenase so that it can be harnessed for solar hydrogen production.
“You can trick bugs to make lots of certain kinds of proteins, like a little factory,” Dyer explains. “It’s called ‘directed evolution,’ where you push bacteria a certain way, forcing them to adapt and to produce an evolved protein that has the properties you need.”
His goal is to generate hydrogenase in a form that allows the protein to bind to quantum dots, which are good at absorbing light and could provide the energy to drive the reaction.
“We envision producing hydrogen in a photochemically driven process, where the electrons and protons needed to produce the hydrogen are furnished by water,” Dyer explains. “You could then burn the hydrogen as fuel and get water back. It would be a perfectly clean cycle.”
At Emory, Dyer is teaming with other scientists in his experiments, including Tim Lian, William Henry Emerson Professor of Chemistry and a leader in quantum dot technology, and Stefan Lutz, an associate professor of biomolecular chemistry who specializes in protein engineering.
Dyer will also serve as the director of a renewable energy center on campus. The aim is to further integrate ongoing energy research among chemists, physicists, biologists, and computer scientists.
“The energy field has suffered from thirty years of people saying that the search for more energy is an engineering problem,” Dyer says. “Actually, it’s primarily a science problem. Most of the advances in renewable energy are going to be made at that interface.”