8 Cray Cray Ways to Harness Solar Energy
A look at some of the most unusual ways to harness the sun for power.
Solar power has become fairly pedestrian since the first photovoltaic cells came out of the lab in the 1950s. Today, utility-scale solar farms soak up the sun and photovoltaic panels dot rooftops across the world. The power generation is finding its way into transportation, too, alongside other clean-burning fuels like hydrogen. Just a few years ago, the Solar Impulse prototype plane flew nonstop without any fuel from San Francisco to New York. And companies like Toyota are looking to bring hydrogen cars mainstream.
"The U.S. was really the pioneer of the whole global solar photovoltaic industry," said Juris Kalejs, an IEEE member and CTO of the Lowell, Massachusetts-based solar developer American Capital Energy. Having worked in photovoltaic technology development for more than 30 years, Kalejs has seen wild ideas come and go. The energy crisis of the 1970s spurred dozens of pie-in-the sky ideas, he said. But that hasn't stopped people from innovating. Here's his grounded take on highly unusual ways to harness solar power today.
The Los Angeles-based startup V3Solar made the news rounds last year with its literal spin on solar. Slick renderings showed a design for deep blue solar cells in a cone shape that could rotate. The company says they want to take photovoltaics from flat and static to 3-D and dynamic. A new video V3Solar put out this summer had more details about how its spinning mechanism could maximize energy generation.
Kalejs said he said he thought the setup could work but he was skeptical about the complexity. "It looks like something that's a nice decorative piece you might find in a fountain," he said. The company said it would show its prototypes to potential investors with a non-disclosure agreement.
Other designers are imagining different shapes for traditionally flat solar panels. Going rounder could mean capturing sunlight from every possible direction. Last year the Japanese optics company Kyosemi launched Sphelar Power to manufacture micro-spherical solar cell beads from discarded silicon and electrodes that are wired into a mesh. André Broessel, an architect at solar architecture company Rawlemon in Barcelona, designed glass spherical lenses filled with water that act like solar concentrators both large and small.
Kalejs called Broessel's idea a neat one that would appeal to consumers but pointed to companies attempting a similar technology with 20-foot-diameter solar concentrators. "It's a very tricky system to make and you need to make it on a large scale to make it cost effective," he said.
Scores of scientists are working on artificial photosynthesis by developing systems that chemically convert sunlight, water and CO2 into oxygen and plant fuel. Unfortunately, photosynthesis has less than a percent efficiency versus 20 percent to 30 percent for regular solar cells, Kalejs pointed out. The risks with artificial plants and microbes are also quite high because a disease or fungus could wipe everything out.
British researchers from the University of East Anglia announced earlier this year that they're working on artificial photosynthesis by placing minuscule solar panels on microbes in an effort to create hydrogen for fuel. Kalejs said he found their approach interesting and added that he's attended National Science Foundation meetings where attendees discussed putting photosynthetic material on top of a solar cell. "Everybody's been looking for a boost," he said.
Effective transparent and thin-film solar cells have been on the technology wish list for a long time. Several companies have already started manufacturing flexible solar panels but rigid ones remain more affordable and easier to produce, resulting in high quality. Earlier this year Stanford University and the U.S. National Renewable Energy Laboratory came up with reusable peel-and-stick solar cells that can be made easily and affixed to just about anything solid: toys, helmets, transistors and even business cards. The resulting power is still relatively small, though.
Kalejs cautioned that sunlight breaks down materials made with polymers, making the technology unstable. "It's a short-life product right now," he said. "The organic solar cells probably wouldn't last more than a year or two, if that long."
One person's trash represents solar tech treasure for someone else. Last year blogger and tech writer Ryan Matsunaga posted step-by-step instructions on how to convert a water bottle into a solar lantern for $2. In February, Kenyan designers launched a Kickstarter campaign around the Bottle Charger, a way to recharge cell phones using a water bottle filled with boiling water and a mini-turbine. Although the initial prototype simply required a temperature differential, the designers hoped to integrate a small solar dish that could heat water with sunlight continuously during the day.
"I have no idea how cheap or stable it is," Kalejs said of the Bottle Charger idea. "I guess you'd say, well if it works, use it."
Solar technology's sleek lines and deep colors are tempting to designers who have incorporated solar cells into purses, necklaces, jackets and mini-dresses. That technology tends to be more high fashion than high function. Charging a phone in a jacket that has a solar power component can take hours. Solar-powered clothing companies have come and gone. Kalejs said that organic solar cell material wears out in a few years so even if the fashion looks timeless, the tech isn't. He remembered seeing a company that turned spherical solar beads into jewelry and said he can still see how it would appeal to consumers.
Roads and highways are a natural lure for solar technology innovators. Asphalt does a great job at absorbing and storing heat. Plus there's so much of it around already -- the infrastructure is there. Several years ago engineers and chemists at the University of Rhode Island created a project to develop ideas for harvesting solar heat from roads. Their suggestions included placing flexible photovoltaic cells on concrete highway dividers and installing water pipes in asphalt. At the same time, the company Solar Roadways wants to embed solar panels directly into roads.
Kalejs was highly skeptical of that, calling it a poor use of solar modules. However, solar modules could be put in conventional arrays beside the road, he said, as they've done in Oregon. There's no shortage of land for that.
Solar panels are a classic that's hard to mess with, but giant arrays beg the question whether it would be easier to just paint photovoltaics directly onto surfaces. Leveraging advancements in thin, flexible solar technology development, researchers have been working on making solar paint happen for real. Two years ago University of Notre Dame scientists experimented with a paste-like paint dubbed Sun-Believable that can generate electricity when sunlight hits it.
"The titanium oxide cells now being used to make dye-sensitized solar cells with efficiencies greater than 10 percent could be incorporated into paint," Kalejs said. He compared that to what's being done with window glass, where transparent window solar cells are being used on building facades.
And this year, scientists at at the University of Manchester and National University of Singapore combined graphene with atom-thin layers of metal to produce a solar-powered coating that could be painted onto buildings.