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photovoltaic panel
(Roy Kaltschmidt/LBNL photo)

Sun struck
Harnessing renewable energy from the sun is a research challenge firing student interest across the campus

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"Student interest in PV seems to be exploding."

–Becca Jones

 4 student researchers

Four students talk about the Berkeley solar outburst and their own research

— After a six-year stint in the business world, chemical engineer Cyrus Wadia decided to "revisit" the solar question: how better to harness, as electricity, the limitless supply of energy from the Sun raining down on Earth. "Every argument about the future of our energy," he observes, "ends with the same comment: 'Man, we have a lot of solar!'"

Now a doctoral student with UC Berkeley's interdisciplinary Energy & Resources Group, Wadia spends many daylight hours in a chemistry lab, synthesizing super-small "nanoparticles" in a three-necked flask apparatus — a technique so simple, he claims, that "anyone who feels comfortable in a kitchen could do it" — then coating his solution on a glass substrate and analyzing his new device for photocurrent. Via these experiments, Wadia hopes to identify a material that is "extremely cheap, non-toxic, and abundant" in nature and suitable for manufacturing photovoltaic (PV) cells. Such a material "may not exist," he admits, "but we have to try."

Wadia's sense of urgency about energy alternatives is shared by many Berkeley graduate students and undergrads across the disciplines who — having grokked the dangers of global warming — are keen to be part of the solution. Their interest is giving birth to new course offerings and campuswide "greening" projects, and stimulating serious research on transportation biofuels and renewable sources of electricity. Among the latter, solar is a frontrunner — though the technical challenges alone, as Wadia can attest, are anything but child's play.

Traditional silicon-based photovoltaic (PV) cells have been around for decades, but they're fragile, relatively heavy, and still so costly to manufacture that a rooftop PV array remains unaffordable to the average Bay Area homeowner, not to mention the masses in the developing world. Consequently, many of the best scientific minds at Berkeley are attempting to bring solar technology to the next level, some by improving "first-generation" silicon-based PV, others by developing entirely new light-converting technologies.

"In the past few years, student interest has risen dramatically in all energy-related matters, especially photovoltaics," observes Eugene Haller, professor of materials science and engineering. "Many of the best applicants to our graduate program want to work in this field."

Last year, at the urging of Ph.D. student Becca Jones, Haller and Professor Dan Kammen, a campus expert in renewable and appropriate energy, co-taught "Photovoltaic Materials," a graduate course that had been hugely popular when first introduced in 2004. With nearly 50 takers for the 2006 reprise, grad-student interest proved to be unabated.

'Nanomaterials, because we do them in solution, we could use that solution as a dye. You could be looking at a wall that’s yellow, but that yellow is solar paints. Today this is science fiction; but everything we do is moving us toward that.'
— Cyrus Wadia

One of Berkeley's undergrad PV enthusiasts is senior Kevin Wang, a double major in electrical engineering and materials science and engineering. Wang says his "environmental education and awareness of global warming" predates college, and that he wrote about his interest in solar-technology research in his application to Berkeley. "I feel we really need a better source of energy than petroleum; it's running out soon."

Of the various renewable energy technologies on the table, solar "fascinates me the most because I like electronics," adds Wang. "Everything we use needs electronics — computers, video games, cars." PV, by his lights, is "one of the best" alternatives — "to capture our energy from the sun and directly turn it into electricity.... I always liked solar. Being out in California, we get a lot of it!"

Wang actively sought out PV research opportunities during his college career, eventually landing a role in two different campus projects — one of them creating and testing nanoparticles under Wadia's direction. "I got to see the whole process of how a new generation of solar cells is being made," he says.

Why PV?

While Wadia and Wang explore common elements in a nanoscience lab, Jones is placing her bets on more exotic materials. A materials science and engineering student, she is researching indium gallium nitride, a semiconductor material that shows promise for use in long-lived and highly efficient solar cells. "Coupled with inexpensive mirrors or lenses," says Jones, these devices could focus "a lot of light on a very small solar cell."

A leader of campus environmental efforts (she co-founded "Students for Greener Berkeley" and helped win student approval last spring of a $5-per-semester fee increase to fund projects to "green" the campus), Jones became concerned about rainforest degradation in high school. Along with the public, she has grown increasingly aware of global warming. "Climate change is a serious problem that is going to take a lot of effort to solve. I don't see how solar could not continue to grow," she says.

'Research moves slower than I would expect. I’m learning that it takes years and years to develop a new technology in this field.'
— Becca Jones

Jones is drawn, as well, to the technical challenges presented by photovoltaics — just as many UC researchers before her have explored the frontiers of electronics: "People in California, especially, have a lot of history with semiconductors," she notes.

Postdoc Lucas Wagner, a quantum physicist who does theoretical research on solar — conducting computational studies of nanostructure systems for PV applications — has a similar take on the attractions of solar research. "It's interesting science," he says, "and you feel you can face yourself when you go home at night."

Wagner is part of a research team led by physicist Jeffrey Grossman; Jones is a senior student of materials scientist Eugene Haller; Wadia's campus mentor is nanoscience guru Paul Alivisatos. And that's to name just a few of the groups doing PV-related work at Berkeley.

To bring all this brainpower together, solar-cell researchers from across campus meet twice a month at midday to discuss their research problems, experiments, findings, and frustrations. Launched in spring 2006, the grad student-run PV Idea Lab has grown from about 10 initially to a regular cast of 20 to 30. Free lunch helps. But the main draw is highly technical and stimulating conversation in which issues like ohmic contact and semiconductor band-bending figure large. "It's very directed and very driven, because we all want to solve the same problem, and we can help each other," Wadia says. With representatives from eight different teams now in the room, "it's really starting to feel like a multi-lab collaboration."

Encouraging the adoption of solar

PV buzz at Berkeley extends beyond scientists and engineers to specialists in public policy, economics, and business. That's a welcome development to Wadia, who believes that "bridging pure science with social science is what we need to put a solution on the table." For solar technology to live up to its potential, it needs to be affordable not just to those in the U.S. and Europe, he insists, but in developing nations like China and India — since it's there "where the real demand for energy in the next several generations will be coming."

What does it take to translate breakthroughs in the lab to widely-adopted products in the market? At the Haas School of Business, the spring 2008 course offerings will include "Energy, Sustainability, and Business Innovation," taught by faculty members Christine Rosen and Drew Isaacs, and "Energy and Environmental Markets," led by Severin Borenstein and Jim Bushnell. "Campus interest in alternative energy and greenhouse-gas reductions has taken off in the last two years," notes Rosen, an expert in business and environmental history. "It's a sea change at Haas."

'I’m interested in the uptake of technology — figuring out how you create incentives [for] people to choose what makes sense, in terms of creating an energy future that is sustainable.'
— Merrian Fuller

One of those keenly aware of energy alternatives, and PV in particular, is Merrian Fuller. An MBA student with a bachelor's degree in international relations, her focus is renewable energy and energy efficiency, and how better to streamline their adoption. "A lot of times," she says, "you'll see technology that makes a lot of sense," but that "doesn't get adopted because of financial barriers, because the up-front cost is very high."

Fuller notes that in the U.S. and Europe, subsidies and tax incentives encourage individuals and businesses to invest in PV systems (in California these can cover as much as a third of the cost). Some analysts view such policies as a step forward, since they speed adoption of renewable energy sources. Others argue that they help first-generation PV technology, which may be nearing its optimum efficiency, compete in the marketplace — instead of using the same resources to invent and promote more efficient and affordable products.

"There are several different ways to go about promoting solar, and each needs to be evaluated based on its current and future impact," says Fuller. "If you invest in current technology, would that money be better spent investing in new product development?"

To deepen her understanding, she worked this summer in the New Homes division of SunPower, which manufactures solar cells and installs PV systems. Fuller was tasked with analyzing potential markets for PV installations on large-scale residential projects — asking "Where are new houses being built? Where are the policies and incentives that we might be able to tap into? And what sort of utility rates and rate structures are in those states?" She found that opportunities for solar are growing across the country, and that the California market is far from saturated.

With research interests spanning economic development, international relations, public policy, and the environment, it's not surprising that Fuller is at the forefront of campus interdisciplinary collaboration, as outgoing co-chair of the Berkeley Energy & Resources Collaborative (BERC). The student-run organization promotes contact between students interested in all forms of energy, including PV, and the business community and government. The two-year-old organization currently has at least 300 members across the campus — in law, business, public policy, the sciences, and engineering — and has helped spur the launch of a new academic collaborative, the Center for Energy & Environmental Innovation.

According to Fuller, BERC's goal is to "continually try to mix people from different schools and to make connections that hopefully will lead to new ideas, new collaborations." Global warming is something "we have to take seriously," she says. "... If we want to not create ecological disaster, and continue to live decent lives," renewable energy technologies like PV are "something of vital importance."