The Solar Future May Still Hinge on Old-School Centralized Power Generation

A pervasive, general notion about solar power is that it's an energy alternative whose future might depend on individual action. Unlike, say, coal or nuclear power plants, solar is something that can deployed house by house, street by street. That's empowering, in a way, and aligns well enough with the general DIY (or libertarian/everyday survivalist) vibes of the future-forward tech community, in addition to the parallel/related "be the change"/Whole Foods philosophy of lifestyle activism. Given the right environment, any goofball can plaster their roof with solar panels and, address by address, the oil companies will be fucked into obsolescence. That's fine until you run into an unsunny climate or the general real world of already overtaxed humans who just want to pay an electric bill to whoever and get on with a restful evening because tomorrow's going to be another shitty one.

My point is that centralized power is not a dead concept, and it turns out that effectively deploying solar energy across very large populations might actually depend on centralization. A study out today in the journal Nature Climate Change (re)examines concentrated solar power (CSP), an lesser-discussed alternative solar technology that hybridizes old-school thermal turbine-spinning generation and solar panel technology, and its potential for delivering enough power to provide for the very large scale energy needs of a population. That potential, it turns out, is quite robust, with the study finding that centralized CSP plants could kick out roughly the same amount of juice as a typical coal or nuclear-based power plant, promising enough electricity to handle 70 to 80 percent of demand. What's more, it can do this without adding anything to the overall energy pricetag.

The solar panels we typically consider are based on photovoltaic cells. Incoming particles from the sun collide with these cells, which are electrical conductors, giving formerly chilled-out electrons the boost of energy needed to put them into motion along the cell. Together, all of these newly energized electrons form an electrical current, which is then routed onto a grid or stored in a battery. Battery storage, however, is difficult and inefficient, even at the small scale of single households, requiring the installation of basically a chemistry set in the user's basement or garage. It's getting better, and the future of batteries is just nuts, but even in optimistic schemes, batteries represent a barrier. A far more promising energy storage solution than electrochemistry is not to store power as electricity at all and instead store it as thermal energy: heat. This is where CSP comes in.

CSP doesn't rely on the photovoltaic effect. Instead, it simply converts the sun's energy into heat. Imagine a large array of solar panels, only instead of the conventional super-absorbent black, the panels are mirrors. These mirrors are all aligned in such a way that incoming sunlight is reflected back toward one location, where all of those rays are collected as heat. This thermal energy is then used to heat up some liquid, which turns to steam and, as in a conventional power plant, that steam moves turbines. It's possible to store thermal energy reasonably well with help from molten salt.

This isn't a brand new technology and CSP is being actively deployed across the globe right now, with massive power plants planned in China and Greece. The United States Bureau of Land Management has set aside very large swaths of land in the southwestern corner of the country for eventual CSP projects. Nonetheless, the current study is the first to fully examine the technology's potential at large scales with a very large, connected networks. The advantage of the largest possible network should be obvious: if the sun isn't shining here, maybe it is there.

"We simulate the operation of CSP plant networks incorporating thermal storage in four world regions where CSP is already being deployed, and optimize their siting, operation and sizing to satisfy a set of realistic demand scenarios," the study summarizes. "In all four regions, we show that with an optimally designed and operated system, it is possible to guarantee up to half of peak capacity before CSP plant costs substantially increase." The fundamental barrier remains the possibility of extended periods without sunlight, even with extremely large geographic areas.

"Our study is the first to look closely at whether it's possible to build a power system based primarily on solar energy, and still provide reliable electricity to consumers around the clock, every day of the year. We find this to be possible in two world regions, the Mediterranean basin and the Kalahari Desert of Southern Africa," explains study co-author Anthony Patt. The rest of the world, it seems, will still have to squeeze out electricity in other ways, perhaps from those DIY roof arrays (and all of those  myriad other green energy solutions already on the market or in development) or, better, by cutting our electricity demands in the very first place.