UT Professor's Biosolar Advances Make an Old Energy Source New Again

There are a few ways to go about doing proper science. On one end of the spectrum is the technocrat, with his sterile corridors and context-free calculations. He is the hollow lab coat with no heart inside, the passionless disinterested observer who knows but doesn't care.

And then there are people like Dr. Barry Bruce of the University of Tennessee's Biochemistry and Cellular and Molecular Biology Department. Bruce is an alchemist in a world of bureaucrats, a hands-on researcher and instructor in a field that seeks to harness one of nature's Philosopher's Stones to help address our ever-growing energy needs.

At first glance, Bruce doesn't come off like a guy whose work could one day change how we approach solar energy. He seems a bit laid-back for a researcher, with a vague Lebowski-like quality emanating from somewhere between his unkempt hair and his sandals. He leans back in his seat when he talks science, betraying an ease that's almost too comfortable with the subject matter.

But when he does talk, watch out. Bruce's biochemistry pedigree stretches back nearly 40 years, and what may be his most important work—applied photosynthesis, and specifically the emerging field of biosolar energy—has been slowly taking shape in his mind for much of that. Having played an integral role in a series of advances that could soon make biosolar into a viable alternative energy source, Bruce's demeanor may just be that of someone who is 10 moves ahead, waiting for the rest of the world to catch up.

With biosolar systems, the active ingredients aren't mined and processed, but instead cultivated. "We can grow it once and use it hundreds of times," Bruce says. "With biomass, you typically grow it once and use it. One crop of switchgrass or one crop of algae is one cycle. But when we make our product, it can be used over and over again. So you might grow it for six days, but then you make the device and it's used for a hundred days, or a thousand days."

Biosolar energy is a pretty simple concept. Traditional silicon-based solar cells have never been cheaper or more prevalent, but they remain an inefficient imitation of photosynthesis, the process by which plants and some single-celled creatures have used sunlight to generate energy for billions of years.

So why bother with a knockoff of photosynthesis, biosolar proponents ask, when we already have access to all sorts of organisms that long ago evolved components that can do the real thing better?

Bruce's work harnesses the capabilities of a subcellular dynamo called photosystem-I, a protein complex integral to photosynthesis that, if utilized correctly, can take the place of much of the synthetic elements of traditional solar cells.

Photosystem-I isn't the kind of thing that can be put together with parts off the shelf. "These are sophisticated macromolecular complexes that we can't build ourselves," Bruce says. "We have to have a living organism build them, and we take them out of the organism and functionalize them in new ways to make them do new things."

Roughly translated, if you can come up with enough photosystem-I and wire it into a solar cell, then bingo! Cheap, easy solar energy.

Actually getting your hands on the stuff is relatively easy. Bruce had this part of the process down as early as 2001, when he and colleagues adapted work he did in graduate school to come up with a system that produced molecular hydrogen when exposed to light. Until recently, the hard part was getting harvested photosystem-I to remain stable over long periods of time. Recent advances have addressed this issue, leading to a system that can remain up and running under normal sunlight for 90 days or more.

What sounds like an incremental change is actually the turning point that could kick interest in biosolar energy into high gear. Once the system is efficient enough, Bruce sees it as a quick and easy solution to filling basic electricity needs in areas that lack the necessary infrastructure to be provided for in more conventional ways.

"You could take a genetically engineered strain and go to a less developed place that had sunlight and water, grow this and isolate [photosystem-I], and make a low-power solar cell that would work for weeks to months," Bruce says. "We can grow it once and use it hundreds of times. With biomass, you typically grow it once and use it. One crop of switchgrass or one crop of algae is one cycle. But when we make our product, it can be used over and over again. So you might grow it for six days, but then you make the device and it's used for a hundred days, or a thousand days."

The whole process is just a bit Frankensteinian, with photosystem-I harvested wholesale from the corpses of a few thousand unlucky cyanobacteria (or spinach, in the case of Bruce's earlier experiments) and rewired into completely alien systems. A fresh batch can be purified in a few days; at any given moment, a prime patch of laboratory real estate might contain a vat of green liquid watched over by an attentive research assistant like Melissa Bigler, an undergraduate BCMB student who works in Bruce's lab.

"I think a lot of times people want to take the avenue of, ‘Well, we can artificially construct this,' but these have had millions of years to work out the kinks," Bigler says. "We would never be able to produce a man-made version of this that's as perfectly efficient as what we have here."

Bruce wants as much as possible as early as possible from his students. "I don't want a student for a semester, I want him for two years at a minimum. We have to build a skill set here that will allow them to become more productive and independent." He expresses no surprise when students who stick around reap benefits from it. Despite being only two years out of high school, Bigler's work has already netted her an upcoming summer fellowship with the Army Research Laboratory.

Bigler is no anomaly; Bruce's lab alumni list includes many similar accomplishments. Awards and fellowships show up by the dozen, punctuated by the occasional national award, like Bruce Lab alumnus Carole Dabney-Smith's recent Presidential Early Career Award for Scientists and Engineers.

"Barry definitely feels that the younger the student is going into the lab, the better their experience will be," says Khoa Nguyen, a BCMB graduate student who sought work at Bruce's lab after graduating from UT with a bachelor's degree in microbiology. "It might take a year in here before a student knows enough to actually be able to do something useful, and they appreciate that a lot more than if they just go in later and figure a couple of things out just in time to graduate."

The approach can have its downsides. "We have a lot of training that goes on here," Bruce says. "For a little bit of discovery, there's a lot of education. It can be a distraction, if we get too bottom-heavy. If we're just teaching people, there's a lot of value for the student, and that's great for them, but the work doesn't move forward."

But as an educator as well as a researcher, Bruce sees the value in long-term cultivation. "The hope is that, if they're here for a certain window of time—probably six months or so—they're able to work and be productive on their own." Bruce says. "If they stay here long enough, then the whole system moves faster."