by Susan King
Hambourger developed an interest in photosynthesis during college, and his research focuses on adapting principles learned from photosynthetic organisms to improve renewable energy systems.
"Photosynthesis is a fundamentally amazing process," Hambourger said. "The vast majority of life on Earth is powered by the sun via photosynthesis. Likewise, the vast majority of human marketed energy is obtained from the sun via photosynthesis. The fossil fuels that comprise more than 80 percent of the energy used in the U.S. all came from the sun; albeit an ancient sun of a few hundred million years ago, with that solar energy stored safely in the ground in the form of chemical bonds."
Hambourger said an environmental studies course he took as an undergraduate at Appalachian "opened my eyes to the challenges facing our species, and a plant physiology course showed me the inner workings of plants at a chemical level. As soon as I began drawing connections between these two topics, I was hooked."
Hambourger graduated from Appalachian with a bachelor's degree in biology in 2001. Following a stint in the Peace Corps in Morocco, Hambourger entered graduate school at Arizona State University, where he focused on chemistry for his doctorate.
" I am glad to have had undergraduate training in biology. However, I thought chemistry would provide me with the best chance to make a difference, by developing technologies that can minimize our environmental impact," he said.
"My graduate work was in artificial photosynthesis, which aims to mimic the magic of plants in human engineered systems," Hambourger said. "Plants are amazing, but they also are highly inefficient. Most of the day, plants are working to get rid of excess solar energy. Plants typically do not grow well in the winter, and they are green rather than black, which means there is a lot of visible light that is not being harvested. The idea of artificial photosynthesis is to strip away the evolutionary baggage of the plant and build a small chemical system that can achieve the same type of energy conversion, but more efficiently and with human needs in mind."
In his laboratory, undergraduate students are working to develop catalysts to convert electricity into stored chemical energy. How does this relate to photosynthesis?
Technologies exist to generate electricity from renewable energy sources. However, our ability to store this energy has lagged behind. This matters, he said, because the sun doesn't shine at night and the wind doesn't blow all of the time. To use renewable energy at these times, storage is required. Storage also is critical for transportation, since a vehicle requires lots of energy in a compact and light form.
In order to store renewable electricity, Hambourger is studying cobalt complexes that catalyze the production of hydrogen gas using electricity.
"The goal would be to take renewable electricity, apply voltage between two electrodes placed in water, and collect the hydrogen and oxygen gasses that are produced at the respective electrodes," he said.
The hydrogen gas could be collected and then burned on demand, releasing the energy stored during the electrolytic process.
"On the surface, it seems far removed from photosynthetic plants, but there are a large number of parallels between plants and renewable energy technologies," Hambourger said. "At the most basic level, plants use sunlight to drive unidirectional electron flow, which is highly analogous to the light-driven flow of electrons that occurs in a photovoltaic panel. Likewise, the catalysts we are developing fill the same role as enzymatic catalysts in photosynthesis. Nature has been doing photosynthesis for a few billion years, there is a lot that we can learn by studying that example."
Currently, renewables account for less than 10 percent of the energy used in the United States.
"Right now our society is spoiled by abundant, cheap fossil fuels. The public is not going to adopt renewables if it doubles the cost of energy. So catalysts have to be dirt-cheap. Catalysts also have to be highly efficient. Cobalt is one of a few metals that seems to have the right chemical properties while also being Earth-abundant and inexpensive," he said.
Asked how his research fits into the big picture, Hambourger explains, "We continue to find new fossil fuels, and seem to have sufficient reserves to meet projected energy demands, at least until 2100. So, I'm not too worried about running out of fossil fuels. Prices may go up if supplies are constrained, but markets can handle that.
"However, climate change is real and very scary. Humans have collectively pushed our atmosphere to conditions not seen in at least a half million years, probably much longer. Carbon dioxide is a known greenhouse gas. We know that humans are emitting carbon dioxide into our atmosphere by burning fossil fuels. The intentional delusion that is required to not put the pieces together and acknowledge that human activities are warming the planet boggles my mind," he said.
Hambourger sees this as a self-correcting problem.
"Life on Earth will evolve to maximize reproductive fitness under prevailing climatic conditions," he said. "It is by no means apparent that homo sapiens will prove quite as versatile. I view climate change as the defining challenge of our times. The time to act was 30 years ago. Renewable energy might be a solution to this problem, and perhaps our research can make a small contribution toward that end. But let's be honest. I like driving my car at 60 mph. I like flipping a switch and receiving instant gratification. I suspect we will use renewables to justify our excesses, rather than to live within the carrying capacity of our planet."