The $2.2 billion DOE-funded Ivanpah solar thermal power plant delivers power for the first time:
From one perspective, things don’t look good. When you calculate the amount of power the plant is likely to produce over its lifetime, the cost per kilowatt-hour is likely to be much higher than for fossil-fuel power. It’s even likely to be higher than the cost of power from solar panels, thanks to the fast drop in solar-panel prices in recent years. If costs don’t come down — and decreasing the costs of mirrors and steam turbines is hard to do — solar thermal power might prove to be a dead end.
But solar thermal power has one chance at success. It’s the only form of solar that can run around the clock, even after the sun goes down (see “A Solution to Solar Power Intermittency”). This is possible because it’s relatively cheap to store heat produced during the day in the form of molten salt which can be used to make steam at night.
Solar thermal strikes me as a hedge or a back-up plan, not the go-to strategy for the next generation of power production.
You’re correct that solar thermal is more of a fallback technology. Solar photovoltaic is a lot more practical for a number of reasons. Of course, “more practical” is still not very. It seems that the two things that could make solar really work for large-scale power production would be:
1. Bringing multiple band-gap PV materials to the point of mass production and reliability that single band-gap PV has right now. I know some people working on this, but it’s still very much in the experimental stage with the panels costing multiple thousands of dollars per square inch.
2. A totally unexpected way of storing solar energy; maybe something along the lines of a high-efficiency artificial photosynthesis or an unforseeable materials science advance.
As a standalone solar thermal system, I suspect the economics on this plant are very bad because no matter how hard you look for the details of the contracts they have with the utilities, the only thing you can find about the cost per kWh is that it’s a secret. Obviously it is so high that everyone involved is scared to death of the public/ratepayers finding out. And like everyone else, I have to ask “where do they go” to lower costs.
If you assume a future where a higher percentage of sources are unreliable then obviously there is more value in a reliable source. But if you look at thermal storage, no one has been able to make that economical and how do you lower the cost of salt to improve that?
But Ivanpah has one trick up its sleeve: they cleverly sited themselves right next to a large natural gas pipeline. If the utilities have a need for more on-demand power, Ivanpah simply needs to install a natural gas burning boiler and they will be able to make steam and turn the generators any time needed.
Another future possibility would see Ivanpah converted to a hybrid facility called an integrated solar combined-cycle plant. On the generation side, it would be a two stage turbine like any other combined cycle plant: first a high temperature gas turbine whose exhaust goes into a boiler for a steam turbine.
On the hot side, the working fluid would first run through the solar tower for preheating and then into the gas fed “boiler” for superheating.
GE is working with eSolar to develop this kind of technology.
http://www.technologyreview.com/news/425012/ge-invests-in-solar-thermal-company/