The 392-MW Ivanpah solar thermal plant in California near Primm, Nevada officially goes online today, with a dedication ceremony.
Celebrities include execs from the project’s creators NRG Energy, Bechtel, and Brightsource, and financial backers Google and the Department of Energy’s Loan Projects Office which provided a $1.6 billion loan guarantee. Energy Secretary Ernie Moniz is flying in to do the ceremonial honors. Grammy-nominated rock band The Fray, which used Ivanpah as the backdrop for their “Helios” album cover and a music video, reportedly will be performing.
Crescent Dunes in Nevada, another solar thermal plant, starts commissioning this week with a series of start-up procedures, testing the system slowly before coming online with full power. It stores excess heat in molten salt so energy can be produced at night too.
Solar thermal power plants can use twice as much water as fossil fuel plants and are generally in deserts. The problem is obvious, water is pumped from aquifers. The primary advantage solar thermal has over solar photovoltaic (which uses practically no water) is energy can be stored for later use. Solar thermal reflects the heat of the sun to a central tower to power steam turbines. Excess heat can be stored in molten salt and used to create power when the sun isn’t shining. This makes power production steadier and more reliable.
Newer solar thermal plants use dry cooling rather than evaporation. However, it is costlier and doesn’t work efficiently on hot days, forcing cutbacks in production precisely when it is needed the most.
One approach to solving this problem is to oversize the cooling system so that it can deliver enough cooling even on hot days. That’s the approach taken by the developers of California’s new Ivanpah solar thermal plant, which is about to start production. But it adds to the cost of an already expensive system.
However, the extra cost is generally about 5% of the total construction cost and reduces water use by 90% over traditional methods.
The Gemasolar solar thermal plant in Spain uses molten salt to store excess heat from the sun to power turbines at night. It recently produced electricity day and night for a record-breaking 36 days. Solar thermal uses heliostatic mirrors to reflect the heat of the sun to a central tower to heat water which powers the turbines. Many solar thermal system convert the steam back to water, thus hugely cutting water usage.
Molten salt is used in solar power tower systems because it provides a low-cost medium to store thermal energy and operates at temperatures that are compatible with steam turbines as well as being non-toxic and non-flammable.
Brightsource has cancelled plans for a ginormous solar thermal plant on 4,000 acres of desert near Blythe CA, citing costs. A similar plant in Inyo County has been suspended. The Calico Solar Project in the Mojave has also been cancelled, due to “changed market conditions.”
All three projects were planned to be solar thermal, where the heat of the sun is reflected to central towers to drive turbines. However, the rapidly dropping cost of photovoltaics made the projects less economically feasible. Plus, solar thermal uses water to power the turbines, and no matter how much the water is reused, it still uses large amounts of water compared to solar PV, and in deserts where water is scarce. On top of that is the problem of getting the power from remote deserts to cities. New transmission lines often need to be built, creating more delays. And of course there are environmental concerns too.
California has ambitious plans to have 33% renewable energy produced within the state by 2020. These plants would have totalled more than 1.5 GW. Their cancellation makes California’s goal more difficult to reach.
BrightSource just cancelled a proposed solar thermal plant due toÂ uncertainties surrounding transmission lines, costs, and the time involved in making changes to plans. They wanted to change their Hiddens Hills construction plans in Inyo County CA to include molten salt heat storage so the plant could generate electricity even when the sun isn’t shining. But this would have meant starting all over again on permits.
Solar thermal reflects the heat of the sun to a central tower to power turbines and can store the heat in the molten salt. However the price of solar panels keeps plunging, plus solar thermal uses water, sometimes lots of it, in deserts where water is scarce. By contrast, solar panels use practically no water.