Crescent Dunes Concentrated Solar Power Tower Will Power Up in March

Crescent Dunes Concentrated Solar Power Tower Will Power Up in March

Crescent Dunes Concentrated Solar Power will begin commercial operation before the end of March, and SolarReserve’s south-central Nevada solar project won’t stumble out of the gate the way power-tower forerunner Ivanpah

Crescent Dunes Concentrated Solar Power will begin commercial operation before the end of March, and SolarReserve’s south-central Nevada solar project won’t stumble out of the gate the way power-tower forerunner Ivanpah did, CEO Kevin Smith said in an interview with Breaking Energy.  

It would be an understatement to say there’s a lot riding on him being right.

Crescent Dunes, a three-hour drive north of Las Vegas, has been in an extended commissioning phase, gearing up since February 12, 2014, to feed power to NV Energy. That just happened to be one day before U.S. Energy Secretary Ernest Moniz and other notables celebrated the opening of the Ivanpah Solar Electric Generating System, 210 miles south of Crescent Dunes, in California.

Both projects were backed by big federal loan guarantees – $1.6 billion for Ivanpah and $737 million for Crescent Dunes. In addition, both projects are in line to have 30 percent of their construction costs reimbursed by U.S. taxpayers through a variation on the Investment Tax Credit for solar.

That federal backing has put a spotlight on the desert projects, but they’re also being closely watched because the basic technology they use to produce thermal power – sprawling fields of giant, computer-controlled mirrors reflecting light atop skyscraper-tall towers – is seen as the best hope for concentrating solar power in what has lately been a losing battle with cheaper photovoltaics.

Crescent Dunes, with the advantage of energy storage, could help repair power-tower tech’s image, which isn’t exactly shining brightly after a year in which Ivanpah became enmeshed in controversy – not always fairly, it could be argued – over bird deaths and low energy production.

Avoiding a similar fate at least partly explains why SolarReserve’s commissioning phase has taken so long.

“We certainly recognized that Ivanpah got hammered,” Smith said late last week. “From a management perspective, that led us to want to be more cautious.” But Smith was quick to add that the “rocket scientists” working on Crescent Dunes – SolarReserve’s technology comes from space propulsion company Rocketdyne – wouldn’t have had it any other way.

After Ivanpah’s early production woes were revealed, BrightSource Energy and NRG Energy, co-owners along with Google, said that all along they thought it would take at least four years to work out all the kinks at their three-unit, 372-MW plant. Different story with SolarReserve and its 110-MW plant.

“We believe we’ll be operating at our expected output within the first 12 months,” Smith said. “We don’t expect a four- or five-year ramp-up.”

The number Crescent Dunes is shooting for: 500,000 megawatt-hours annually, which computes to a capacity factor around 52 percent. (Through its first 11 months, Ivanpah’s capacity factor was about 14 percent.) Crescent Dunes will sell the electricity to NV Energy at 13.5 cents per kilowatt-hour, with the price rising 1 percent a year during the life of the 25-year power purchase agreement.

As for birds, Smith believes Crescent Dunes has a “site selection advantage” at its location outside the town of Tonopah. “It’s a remote area with not a whole lot of food for birds…. There’s very little wildlife in the area.” He said that during commissioning they “haven’t had any issues with regard to birds.”

Like any CEO would, Smith likes his product better than his competitor’s. Still, there’s no disputing that with energy storage, Crescent Dunes has an edge over Ivanpah as grid operators deal with the challenge of bringing more intermittent renewables online.

Instead of directly boiling water the way Ivanpah does, at Crescent Dunes a mixture of sodium and potassium nitrate is heated atop a 640-foot-tall tower that is bombarded with focused sunlight. That molten salt can be used immediately to superheat water, or stored in insulated tanks to drive the thermal-power process during cloudy weather or at night. The ability to store energy means Crescent Dunes doesn’t need supplemental natural gas to operate efficiently, unlike Ivanpah.

The 16-month-old, 280-MW Solana Generating Station in Arizona, which produced 606,385 MWh in the one-year period from December 2013 through November 2014, can also store energy. But its system uses arrays of long parabolic troughs, which focus the sun’s heat on an attached tube that has a transfer fluid running through it. That fluid is used to boil water or to heat the salt.

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“We’re using molten salt directly,” Smith said, giving Crescent Dunes the ability to drive the temperature of the heat-holding salt 300 degrees higher than at Solana. “They need two or three times the salt we have to get the same amount of heat storage,” Smith said. That leads to a bigger, more expensive footprint – “a whole lot more tanks, pumps and salt.” The multistep nature of the Solana process also results in less efficient operation, Smith said.

Even Solana’s owner Abengoa now favors towers over troughs, with a company executive telling Sammy Roth at the Desert Sun that it’s cheaper to build energy storage for solar towers than for parabolic troughs, and that any future CSP-with-storage projects the company does in the desert will likely be of the tower variety.

But will there be future projects? California, with its aggressive renewable portfolio standard, would seem to be a likely candidate, and it even has an energy-storage requirement for its big investor-owned utilities. But longstanding power-tower projects – Abengoa’s Palen project, SolarReserve’s Rice project, BrightSource’s Hidden Hills – are on hold now because the Investment Tax Credit is set to drop from 30 percent to 10 percent at the end of next year. A big PV plant could be built by then, but it’s not enough time to get a power tower done.

As for the energy-storage mandate, Smith says it “probably isn’t robust enough” and utilities still “are not feeling the heat” enough to pursue big-time storage with gusto. As he had in a recent interview with CSP Today’s Susan Kraemer, in our interview Smith pointed to Southern California Edison’s ballyhooed Tehachapi Energy Storage Project to illustrate how timid the energy-storage pursuit is right now.

Sure, Tehachapi might be the “largest battery energy storage project in North America,” as Edison called it – but it will store just 32 megawatt-hours of energy. And it will cost $50 million. Crescent Dunes will be able to store up to 1,100 MWh, 10 hours of full output. At a cost of $975 million, it appears to offer a lot more bang for the buck.

Smith said that if and when the state gets serious about large-scale energy storage, SolarReserve’s technology will step to the fore. Meanwhile, he expects his engineers to chip away at costs in future projects, three of which are solidly in the pipeline in South Africa and Chile, where the company is also developing PV plants, some in a hybrid setup with the towers.

“Right now, we’re focusing on international markets because those markets are ready,” Smith said. “California is going to get there eventually…. It might just take a few years to take hold.”

A good showing at Crescent Dunes could only hasten the process.