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The Future of Solar Technology Is Still Wide Open

Solar panels are cheaper for the moment, but the government's not giving up on solar towers yet.

The Department of Energy announced this week that it will hand out $60 million over the next three years for research into concentrating solar power technology, the ugly duckling cousin of the more popular solar panel systems. Considering the beating that Congress and the Beltway press have laid on the government for funding clean energy projects, the Energy Department comes off as brave for pushing forward with solar research at all. But the new investment also shows the importance of exploring multiple options to wean the country off of gas, coal, and oil.

“Concentrating solar power” projects are more futuristic and fantastic than the name makes them sound. A CSP solar installation might feature a desert tower hundreds of feet high, lording over a field of mirrors arrayed around in it. At the tower’s top, a single point collects solar energy reflected by those hundreds of mirrors. That single point collects enough energy to heat water into clouds of steam, which in turn drive a turbine and create electricity. Or it heats gallons of molten salt, which can store that energy for use when the sun doesn’t shine. Other CSP systems use long, mirrored troughs to collect and concentrate solar energy on a bar running down a trough’s axis. The troughs track the sun, turning their faces towards the light like flowers do. A third type of CSP, a dish-and-engine system, resembles a large satellite dish.

It’s expensive to build a looming solar tower, until recently, these projects compared favorably to solar panel projects on cost. But solar panels have become so cheap that the solar industry has shied away from any alternative. More than one solar company has converted a solar tower projects into a solar photovoltaic project in the past few months. That’s the problem that the Department of Energy is asking applications to address. It’s looking to fund research that will bring down the price of CSP projects: ideas like putting the mirrors on a hill, instead of around a tower, to decrease the cost of pumping water or molton salt hundreds of feet into the air.

If the price of solar panels keeps dropping, the Department of Energy’s continued interest in solar towers might seem like another misguided fantasy. But there are plenty of reasons why the price of panels might stall out. American solar manufacturers could be right that China is dumping panels here at unfairly low rates. The supply of rare earth materials that go into thin-film solar panels, the cheapest per watt to produce, could dry up. (China also controls this resource, and its largest rare earth supplier recently decided to shut off supply.) An alternative to panels might be welcome in the near future.

But the solar industry is small enough right now that it doesn’t have the resources to hedge against those possibilities. Solar companies want to install as much capacity as they can, while the government is still incentivizing those projects. They don’t have the capacity to continue innovating in solar towers when solar panels are cheaper. The Department of Energy, on the other hand, does.

Solar towers and their siblings might end up being “losers” in the long run. But what happens if the solar industry is making the wrong bet by going all in on photovoltaics? To push back on climate change, renewable energy sources like solar need to take over a significant portion of the country’s electricity generation—right now, solar contributes about 1 percent of the country’s energy. The Department of Energy is right to keep researching a backup plan for photovoltaic systems: if the country is left without a way to keep expanding solar power cost effectively, we’ll all lose out.

Photo courtesy of Sandia National Laboratories

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