This ‘Other’ Form of Solar Energy Can Run at Night, and It Just Got a Big Backer - by Joe Romm

Converting sunlight directly into electricity, the photovoltaic (PV) solar panel industry has dominated the solar generation market recently because of its astounding price drops.  Prices have fallen 99 percent in the past quarter century and over 80 percent since 2008 alone.  This has also helped to slow the growth of the “other” form of solar, concentrating solar thermal power (CSP), which uses sunlight to heat water and uses the steam to drive a turbine and generator.

Fortunately, one country appears to be making a major bet on CSP — China.  SolarReserve, the company that built the Crescent Dunes plant (pictured above) recently announced a deal with the Shenhua Group, the world’s largest coal provider, to build 1,000 megawatts of CSP with storage in China.  And the country as a whole has plans to build some 10,000 megawatts of CSP in the next five years.

I say “fortunately” because CSP has one huge potential advantage compared to PV.  The heat it generates can be stored over 20 times more cheaply than electricity — and with far greater efficiency.  So CSP’s “killer app” is that it can provide power long after the sun has set — and it doesn’t disrupt the grid when a cloud passes overhead.
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Because of its built-in cheap, efficient storage, CSP — aka Solar Thermal Electric (STE) — has the ability to directly address the “variability” or “intermittency” problem that PV has when the sun isn’t shining.  As a result, the 2014 STE Technology Roadmap from the International Energy Agency (IEA) concludes that while PV could generate 16 percent of the world’s electricity by 2050, as much as 11 percent could be generated by STE at the same time.

In this scenario:  “Combined, these solar technologies could prevent the emission of more than 6 billion tonnes of carbon dioxide per year by 2050 — that is more than all current energy-related CO2 emissions from the United States or almost all of the direct emissions from the transport sector worldwide today.”
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Both the IEA and the U.S. National Renewable Energy Lab have said that after solar PV makes a deep penetration into the electricity market, CSP will likely become more valuable.  A 2014 NREL study found a CSP project with thermal storage “would add additional value of 5 or 6 cents per kilowatt hour to utility-scale solar energy in California where 33 percent renewables will be mandated in six years.”

Right now, solar PV produces power at the most valuable time — the daytime peak in electricity consumption, especially during the summer, when air conditioning use creates a huge power draw.  But once solar PV hits 10 percent to 15 percent of annual electric generation in a region, it can become less valuable.  The IEA projects that when that occurs, perhaps around 2030, “Massive-scale STE deployment takes off at this stage thanks to CSP plants’ built-in thermal storage, which allows for generation of electricity when demand peaks in late afternoon and in the evening, thus complementing PV generation.”
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For a while it seemed as if the United States would be that big driver, but CSP was stalled by the collapsing price of PV.  Also, the reputation of CSP as “green” was harmed in this country by a shocking estimate of 28,000 birds burned a year by one CSP facility — an estimate that turned out to be no more than pure speculation.  The actual number of birds burned in one year appears to be 700 — and that was before any abatement actions were taken.  It turns out that just using standard strategies to ward off birds can cut that number by two thirds.  And the Crescent Dunes facility built by SolarReserve (see top picture) was able to virtually eliminate bird burning entirely by changing how the mirrors were operated when in standby mode.
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The continued expansion of CSP worldwide is crucial to reducing its costs, just as it was for wind and solar PV.  Obviously, CSP has a very long way to go to catch up to PV, which hit 227 gigawatts of capacity in 2015 and continues to rise rapidly.

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