|Valparaiso University Alumna Katie Kruger
in Front of Solar Simulator
Photo of Katie in Laboratory
The stories of how Katie Kruger '08 became interested in solar energy and how she ended up pursuing her doctorate at the University of Minnesota are pretty similar: They both started in Valpo's International Engineering Program (VIEP).
Krueger studied mechanical engineering with a secondary major in German. During her second and third years at Valpo, she lived in the Kade-Duesenberg German House, where she was able to practice German conversation each night over dinner with her housemates.
Those two years of practicing the language were good preparation for her fourth year, most of which she spent in Germany, taking classes for several months before beginning an internship at the German Aerospace Center in Stuttgart. The internship is where she first started working with solar research, which has remained the focus of her studies since then.
"I was really drawn in by the prospect of doing research to further the development of renewable energy," Krueger said. "I think it is quite important to protect our natural resources and to come up with more sustainable alternatives to electricity."
After Krueger and fellow VIEP students Nate Leonard and Peter Krenzke '08 spent their senior year designing and building a solar-powered reactor to separate zinc and oxygen, they traveled to Switzerland with Robert Palumbo, professor of mechanical engineering, to test it.
At the Paul Scherrer Institut (PSI), a multi-disciplinary research center in north-central Switzerland, Krenzke, Krueger, and Leonard were able to witness the functionality of their design when concentrated sunlight was applied.
The excitement has not worn off. Three years later, Krueger is making tremendous advances in solar engineering research. She is currently testing the output and efficiency of the first solar simulator in the United States, which she designed. The simulator is currently operational at the University of Minnesota Solar Energy Laboratory. Her project, called “Experimental characterization of reacting systems under direct high-flux irradiation,” is intended to be a model for other research institutions that may want to build a reactor of their own.
“I enjoyed the excitement of doing completely new things in research, so I decided to take it a step further,” she said. Krueger began working on the solar simulator about halfway through her first year at University of Minnesota. For the remaining two and a half years, Krueger has designed, modified, predicted, adjusted, and measured the operation and power of the simulator.
“The reason we opted for a solar simulator is so we can really control the conditions we are exposing the reactors to,” Krueger said. “Our experimental conditions are then extremely repeatable and reliable so we can characterize the reactors really well. With natural sunlight, we don’t have that kind of control. A cloud might come by when you aren’t expecting one, and your power decreases. It’s still possible to work with natural sunlight, but if you are in the middle of an experiment, it’s really not the best time for a cloud.”
She designed the simulator to use seven xenon arc lamps — electrically-powered light sources that use xenon gas to mimic sunlight — and concave, football-shaped reflectors to concentrate the artificial sunlight to a point about three inches wide. She used complex mathematical designs to establish the geometric relations necessary to focus the lamps and is now measuring the flow of energy, or flux. And when she’s done, she’ll receive her doctoral degree.
Also pursuing doctorates at the University of Minnesota are Krenzke, Luke Venstrom ’07, and Leanne Matthews ’10, each of whom is conducting solar fuel research at the University of Minnesota Solar Lab.
“We all greatly valued our Valpo experiences, and all of our projects help round out the picture of the solar research happening here at University of Minnesota.” Krueger said.
Leonard is currently researching the role of catalysts in fuel cells. He is a research assistant at Michigan State University, where he is pursuing a doctorate degree in chemical engineering.
“Not only are they all brilliant students who will do great things, they are also exemplary individuals,” said Scott Duncan, assistant professor of mechanical engineering and senior design advisor for the reactor team that traveled to Switzerland. “They are all good people, treat others with respect, and work very hard.”
Krueger hopes her hard work will pay off when she seeks a job.
Katie Kruger, Nate Leonard, and Peter Krenzke
“I’d really like to be able to keep using German,” she said, excitement about the perfect job audible in her voice. “If my employer needed me to travel to Germany to meet with engineers and be able to communicate with them, I would really, really like to do that.”
But, she realizes, it might be difficult to combine all the things she wants to do into one ideal job.
“I would like to keep working with solar energy when I’m finished with my degree,” she said, “I at least hope I can work on an initiative for renewable energy, a way to keep innovating ways people use energy and the types of energy they use.”
“I think there will be something out there for me.”