Fall 2018 /What's Next?/

What’s Next in Solar Energy?

solar energyWhen we think about the future of solar energy, we usually think about new generations of solar cells that are more efficient or more affordable or longer-lasting—or some happy combination of the three. Lots of scientists and engineers are at work on that side of the equation, including Professor of Physics David Tanenbaum, whose current research involves the development of perovskite and organic polymer-based solar cells that should be cheaper to produce than the silicon variety.

And yet, while better solar cells will help, Tanenbaum believes the next big step forward in solar energy probably won’t be on the production side at all—it will be mainly about energy storage.

“It’s really about battery technologies, capacitor technologies and other ways to deal with the fact that we’re changing our world from centralized baseline power plants to distributed intermittent energy generation, whether it’s wind or solar,” he explains. “And the storage of that energy is what’s driving utilities like Southern California Edison bonkers.”

The most important leap forward in terms of generation, he says, may already have happened. “Twenty years ago, when we talked about this, the question was, ‘Can we harvest large amounts of energy from the sun and the wind? Will it work?’ Now we’ve said, ‘Yeah, we can do this,’ but the question is, ‘Can we build a system that can deal with energy that’s produced intermittently as opposed to energy that’s produced constantly?’”

Today’s battery technologies were all designed for portable electronics and are far too small and short-lived to do the job, he says. “All batteries, no matter how well you treat them, eventually need to be replaced. For a product like your laptop computer, which you’re going to replace in five years anyway, that’s not a big deal. But for a product that’s part of your energy grid, that’s not a good situation. Our energy grid needs to be made of parts that will last at least 25 years.  Some parts of our grid are 100 years old and still work.”

Eventually, he believes, some new energy storage technology will be built from the ground up to meet that need, but it’s unlikely to look like anything you’d recognize as a battery. “It’s more likely to be heavy, solid, non-portable, thermal, chemical or mechanical energy storage, that will hold significantly larger amounts of energy than batteries designed for portable electronics.”

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