October 2008

Here Comes the Sun

Solar energy is too expensive, but engineer Thomas Vandervelde is working to make it cost efficient for everyone and change the way we use power

By Marjorie Howard

Imagine the roof of your home decked out with $30,000 worth of solar panels. Sure, you could pat yourself on the back for powering your house in such an environmentally friendly manner. But the panels would take a big chunk out of your wallet, and it could take up to 11 years to recoup that money in energy savings. Worth it? Maybe not.

He’s got his eye on the sun: Thomas Vandervelde is testing something called quantum dots to increase the amount of light that gets converted into electricity. Photo: Joanie Tobin

That’s because solar energy is expensive, says Thomas Vandervelde, an assistant professor of electrical and computer engineering who arrived at Tufts this fall. He is researching ways to make solar energy more efficient—and therefore cheaper.

“Solar energy is not cost efficient right now,” he says, explaining that it costs more to produce a watt of energy from the sun than it does with traditional power sources. There are, says Vandervelde, two approaches to bringing down the cost of solar energy. The first is to make solar panels very cheap; the other is to make the panels very efficient.

Researchers around the world are working with polymer-based solar panels and ones made of organic materials, such as carbon. Vandervelde says such carbon panels can be produced cheaply and quickly in factories. “The bad news is you might have to have 10 football fields worth of them to power your house, because they’re so inefficient. Also, the sun breaks the panels down, and you have to replace them every few years.”

Vandervelde is bringing new approaches to the quest for cheaper solar power. One technique uses quantum dots, tiny crystalline structures that enhance the absorption of light. The crystals, which are one ten-millionth of an inch in diameter, are already being used in scientific- and military-grade cameras.

Vandervelde is working with graduate students to fabricate solar panels with quantum dots and with other materials that are sensitive to different wavelengths or colors in sunlight, to test them for efficiency. The standard efficiency level for solar panels is about 12 to 15 percent and the world record is 40 percent. The quantum dots, he says, could boost efficiency by 20 percent and, when combined with other advancements, possibly by 50 or 60 percent.

“By embedding them into a regular panel, you can increase the sensitivity of that panel to the sunlight and extend the wavelengths the panel is able to absorb,” says Vandervelde, who holds the John A. and Dorothy M. Adams Faculty Development Fellowship, a new program that endows a junior faculty position for three years. 

Vandervelde and his students are collaborating with researchers at other universities, including the University of New Mexico, Ohio State University and the University of Virginia, as well as several solar power companies, on the project.

New-fangled Steam Power

Vandervelde came to Tufts from the University of New Mexico’s Center for High Technology Materials, where he was a research professor and intelligence community fellow. In looking for a new position, he says he sought a setting that would be large enough to support research but small enough to have what he calls “quality interactions” with students. He also wanted a university that values teaching.

“That’s what I’ve found at Tufts,” he says. “I had offers from other schools, large Midwestern universities where there are 300 faculty members, and you never see your department head, let alone the dean, and nobody knows who you are. That’s not the environment I wanted to be in.”

In addition to teaching a course on electricity and magnetism and doing his research, he is working with undergraduates on their senior design projects. Based on his idea, the students are designing and building a small, compass-sized container with a solar cell that would fold out like an umbrella and serve as a portable charger for electronic devices such as cell phones and iPods.

Vandervelde is also doing research on thermal photovoltaics, which use ambient heat from things such as light bulbs or water heaters to return heat back to the system.

“The intelligence community is interested in thermal photovoltaics for what they call energy harvesting,” he says. For example, the Navy is interested in using them as a way to convert heat from a power plant directly into electricity. Vandervelde says the process could also benefit consumers because it could be used in everything from cars and power plants to household appliances and electronic devices to manage waste heat and make products more energy efficient.

Marjorie Howard can be reached at marjorie.howard@tufts.edu.

Article Tools

emailE-mail printPrint