|The Crescent Dunes CSP facility, via PowerMag|
CSP stands for 'concentrated solar power', with 'with storage' always understood. In fact, the Ivanpah CSP plant, which is the biggest in the US, doesn't have storage, but the Crescent Dunes facility at Tonopah in Nevada has 10 hours' worth. You can read an excellent detailed article about the Crescent Dunes plant here.
On a normal day, Crescent Dunes begins generating power around 10 a.m., reaches full power around noon, and stays there until 10 p.m. to midnight per the terms of its PPA, which calls for 12 to 14 hours of generation a day. This helps NV Energy meet peak evening demand, and Crescent Dunes shuts down as that demand falls late at night.
But that’s only what it’s contracted to do for the utility. The PPA, in fact, doesn’t exploit the plant’s full capabilities. By reducing its net output slightly, Crescent Dunes can actually operate 24 hours a day, banking excess thermal energy while the sun shines and using it to generate steam all night. As a proof of concept, SolarReserve ran the plant for a continuous 120-hour period during July. While doing so, it was able to maintain full power for most of the day, only ramping down to about 60% power during the early morning hours.
SolarReserve has an array of new plants in various stages of development that will be less expensive and even more efficient than Crescent Dunes, Smith said. Two near-term examples will move substantially past what the company has achieved in Nevada.
The 100-MW Redstone project in South Africa, which breaks ground this fall and will incorporate 12 hours of storage, should see about a 30% decrease in construction costs from Crescent Dunes, as well as reduced construction times. The 260-MW Copiapó project in Chile, with 14 hours of storage, plans to bid its power at under $70/MWh, without subsidies. That plant, using two solar towers and an additional 150 MW of PV generation, is being designed from the ground up to operate as a 24-hour-a-day baseload facility.
Other projects are in the works in China and Australia, Smith said. “We have an agreement with Shenhua, China’s largest coal generator, to build a 10-tower facility, and another agreement with State Grid Corp. to build another 10 towers, though they may not be all on the same site.”
[Read more here]
SolarReserve is planning a new CSP plant in Nevada, which will be the largest solar plant in the world, more than 10 times larger than the Crescent Dunes one:
The race to build the world's largest solar power plant is heating up. California-based energy company SolarReserve announced plans for a massive concentrated solar power (CSP) plant in Nevada.
SolarReserve CEO Kevin Smith told the Las Vegas Review-Journal that the $5 billion endeavor would generate between 1,500 and 2,000 megawatts of power, enough to power about 1 million homes. That amount of power is as much as a nuclear power plant, or the 2,000-megawatt Hoover Dam and far bigger than any other existing solar facility on Earth.
SolarReserve's Sandstone project involves at least 100,000 mirrored heliostats that capture the sun's rays and concentrates it onto 10 towers equipped with a molten salt energy storage system. The molten salt, heated to more than 1,000 degrees, then boils water and creates a steam turbine that can drive generators 24/7.
Compared to photovoltaic arrays, the appeal of CSP systems is that solar power can be used after sunset.
"It's really the ability to provide renewable energy that's available on demand 24 hours a day," Smith told NPR.
[Read more here]
This single plant will provide about 4.5% of California's peak electricity needs.
Note that the electricity from the first CSP plant, Crescent Dunes, was contracted at $US135/MWh, after subsidy, but that the Chile plant costs US$70/MWh, though that includes PV (photo-voltaic, i.e., solar) panels which would reduce the cost. The big advantage of CSP over battery storage is that the CSp tanks containing the molten salts don't degrade over time as batteries do.
Lazard costs the cheapest CSP at US$119/MWh, and PV with battery at $92/MWh (although I question their battery degradation rate of 1.5% per annum; I think that's way too low. But they are more expert at this than I am). The costs of both technologies are falling fast, and I'm not sure which will win out in the end. Probably we'll use both, PV plus batteries at homes and small businesses, CSP at utility level. Whichever wins, in sunny places around the world there will be no technical or economic difficulty switching to 100% renewable electricity generation.
[P.S. Some have expressed concern at birds who are killed flying through the concentrating beams. The fewer birds incinerated, the better. Fortunately, they've fixed that problem]