What if we could switch on the energy of the sun like turning on a tap? That “dispatchability” is what we can have with the thermally stored solar energy available with Concentrated Solar Power (CSP).
Because of its ability to store solar energy, CSP provides a completely different benefit to the grid than Photovoltaic (PV) solar, and far from competing with PV, CSP is complementary to the better-known solar.
And precisely because PV has been so successful and is growing so fast, now CSP with storage is needed as the complement to PV in a completely new grid system. Here’s why the grid is changing to accommodate solar PV.
Once the atomic-level engineering is in, a solar panel is a simple mass produced object, with a simple installation process at utility-scale. The revolutionary simplicity of PV is why prices at utility-scale plunged so fast.
PV’s Success Creates the Need for Dispatchable Power
Because of PV’s simplicity, it is inevitable that it will become the obvious choice for supplying most daylight needs. But with one proviso: solar PV is not dispatchable. You can’t turn it on when you want it. Night falls, clouds pass over.
Intermittent generation like PV needs to be backed with a source that can take care of the predictable hours after daylight. As long as base load power dominated the grid, there was little need for dispatchable power, a flexible form of power that can be delivered on demand.
But that’s changed now. Because it is such a disruptive technology, PV is changing the grid from a base load grid to a lumpy grid with gaps. The very success of PV is creating a new need: dispatchable energy to fill in.
Initially, backup for intermittent renewables had been the job of natural gas.
Natural Gas is Dispatchable but at a Risk
Natural Gas is not Climate-safe
Burning natural gas is a climate risk, just like burning other fossil fuels like coal or oil. Though natural gas emits lower emissions during power generation than coal, methane leaks during drilling and transporting more than make up the difference. Natural gas is predominantly methane.
While the impact of CO2 destabilizes climate for thousands of years, making it the greater danger overall, methane is a 20-times more potent greenhouse gas than CO2 in the short term, with immediate effects that will raise temperatures for the next several decades.
Natural gas is also an immediate physical danger. It is a gas that can literally kill people and animals. Workers must use protective safety gear to produce it. The chemicals used in fracking are suspected of potentially polluting the water table under populated areas.
Despite the dangers of natural gas, very large quantities must always be stored near densely populated areas, ready to burn in power stations, because populated areas are where the demand is high. Leaks are unavoidable, and are costly.
Unpredictable Fuel Costs
Natural gas prices are unpredictable. Over the long run, prices will rise as resources run dry. Typically, a utility passes through the extra cost to customers when natural gas fuel costs rise.
The natural gas industry also faces shortages of workers in the future, due to its unpopularity with millennials. Part of the reason that nuclear power is costly has been the lack of younger engineers coming in to replace older ones as they retire once nuclear power became unpopular.
CSP is Dispatchable Solar
Like a natural gas plant, a CSP plant runs a power block. This makes it as dispatchable as a natural gas plant running a power block. The difference is that it runs on clean solar energy, like PV.
So CSP is the dispatchable form of solar, that can be turned on or off on demand, supplying energy when needed. CSP can use its own thermally stored solar energy to dispatch power any time on demand. CSP is well-suited for covering the recurring gaps in PV generation.
Like the better-known solar, CSP contracts are set at a stable price over a 20-25 year span and CSP doesn’t risk human health throughout its production cycle, won’t emit greenhouse gases, and won’t destabilize the climate. The same cannot be said for natural gas. So CSP has important advantages over natural gas as dispatchable energy.
With PV for daytime and with CSP taking stored solar power into the late evening, most of the hours in a day can be solar-powered. So CSP supplies part of the route to a 100% renewable electric grid, that will include various mixes of PV, onshore wind, offshore wind, hydro, geothermal, landfill gas and CSP with storage.
No one renewable source can do it all. We will need them all. And that includes both forms of solar generation: PV and CSP.