Santa Clara University


Energy Scavengers


Usually, the word “scavenger” conjures up negative images of dirty dumpster diving or creepy vultures awaiting their turn at the fallen lion in the Serengeti, but our own Hohyun Lee, assistant professor of mechanical engineering, is part of a new breed of energy scavengers that is putting a positive spin on the term.

From investigating ways of providing residential consumers with the efficiency of solar thermal energy to developing a health monitoring system powered by the body’s own heat, Lee is tackling the challenges of thermal energy harvesting.

“When talking about solar energy, people usually think about PV [photovoltaic panels] converting light to electrical energy and then converting electricity into thermal energy. Using solar thermal energy directly makes more sense when thermal energy is the final form of application, such as for heating. We know we can generate electricity from solar thermal by using a turbine—that’s been proven with huge concentrated solar thermal plants. But solar thermal has not yet been effectively put to use on a smaller scale, so my students and I are working on adapting the technology for residential use,” Lee said.

In addition to harvesting solar thermal energy, Lee also seeks ways of putting wasted heat to use. “More than half the energy produced—up to 60 percent—is wasted heat,” said Lee. “If we can recover wasted heat effectively, we can reduce fuel consumption by at least 30 percent.”

To this end, Lee is working on generating power from the human body using material with highly efficient thermoelectric properties. “I’m running projects with students this year trying to harvest energy to power a health monitoring system that will send information to a cell phone or health care provider. The undergraduates are researching how to optimize the process of obtaining power from the thermoelectric modules and graduate students are doing modeling work to provide theoretical support,” he said.

Another student project for harvesting thermoelectric energy involves a cook stove. “Wasted heat from the cook stove can be used as a local power source in off-grid communities,” Lee reports. Still more student teams are working on a number of other energy scavenging projects for developing countries, including a water purification system, neonatal incubator, and even a chicken brooder.

Not content with following just these avenues for energy harvesting, Lee and his student scavengers are also busy working on energy storage, solar tracking systems, efficient building materials and more.