SolarReserve Introduces Gigawatt-Scale Solar Thermal Storage Project for California

SolarReserve plans its second U.S. dispatchable solar project to be at the gigawatt scale of a nuclear plant. At 2 GW, the Sandstone Energy 10X project will have nearly 20 times the 110-MW capacity of Crescent Dunes; the California firm’s first fully dispatchable solar plant, able to deliver solar on demand.

This puts the Sandstone at the same capacity as the 2 GW Hoover Dam, at the other end of Nevada from Crescent Dunes. 

Serious Grid-scale Storage

Sandstone is “all about storage,” according to SolarReserve. The gargantuan concentrated solar power (CSP) project would cost an estimated $5 billion and be delivering solar day or night by 2021.

At 20,000 MWh of storage, its solar storage would dwarf the capacity of the 400 MWh AES battery storage bid for Southern California Edison and pronounced “the world’s largest storage battery.”

Sandstone would have 50 times as much storage and would come online in 2021; the same year as the four hours of storage of the AES 100 MW (400 MWh) battery.

Its generous capacity would give Sandstone the flexibility to generate very large blocks of power on demand, morning, noon or night, including California’s peak evening load period. 

Cheapest Stored Solar

CEO Kevin Smith told Renewable Energy World that the price will be cheaper than PV with battery storage, at somewhere “under 10 cents,” a remarkable 25 percent drop from SolarReserve’s first CSP project.

Crescent Dunes had a 13.5 cent per kWh power purchase agreement with NV Energy, negotiated in 2009. 

Back in 2009, solar PV was in the 9 cent range, and is now breaking world records at around 3 cents. But the relatively higher solar price of SolarReserve’s CSP with storage really is not comparable to the price of solar PV without storage. 

If utility-scale PV included battery storage to make it as dispatchable as CSP with its thermal storage, the combination, even at today’s lower battery prices, would likely be 15 cents or higher.

Sandstone would deliver solar at any hour day or night whenever the grid needed the generation, on demand, at under 10 cents.

Longer Life Than Battery Storage

“We are truly bulk energy storage, with large blocks of power that we can move around as required by the utility, even be within the same day, depending on the utility’s power requirements,” Smith said. “Our project in Nevada charges and discharges 1,100 MWh of storage capability every single day, and unlike batteries, there’s no degradation. If you look at some of the top line battery manufacturers, you will see substantial degradation in a few years, while we have no degradation for 30 or more years.”

Sandstone would store each day’s solar heat in molten salt in tanks, where it loses only 1 percent of the stored energy daily, and the heat is tapped to generate steam for electricity generation at any time, in the same way as a gas, coal or nuclear plant. 

So the firm’s solar power can be delivered on demand day or night, unlike solar PV, which needs backup power (often provided by natural gas plants) on cloudy days and peak usage hours in the evening.

The huge project would help supplant California’s requirement for dispatchable natural gas generation, further reducing California’s carbon footprint.

Nevada DNI

Part of what determines a solar price is the level of the solar resource, which for CSP is DNI, Direct Normal Irradiance; or relatively clear unpolluted air with few particles to scatter irradiance. 

For example, in Chile’s Atacama desert, which has the best DNI in the world, SolarReserve recently tendered the world’s lowest bid ever for CSP with thermal storage — at just 6 cents per kWh for 24/7 power delivery that includes 14 hours of full load storage.

The solar resource in the Nevada desert is world class, but not quite at the level of Chile’s Atacama desert.

Where Nevada is well situated is for the huge scale of solar generation that California will need to meet its otherwise impossible targets.

Why California Will Need Stored Solar from Nevada

California’s need for renewable energy is due to both the size of its economy, now fifth in the world, in combination with its very ambitious clean energy targets; 50 percent by 2030.

Recently, California crippled large-scale solar development by a choked off public land supply. The final Desert Renewable Energy Conservation Plan (DRECP) decision very sharply limited the availability of public land for future renewables in California.

“What is singularly unique about the Southwest desert is it is close to some of the country’s major metropolitan centers,” Shannon Eddy, head of the Large-scale Solar Association (LSA), told Renewable Energy World.

LSA who fought unsuccessfully to limit the DRECP kneecapping of renewables.

solarImage: One of the two molten salt thermal energy storage tanks at SolarReserve’s 110 MW Crescent Dunes CSP project. Credit: Susan Kraemer

“There’s really no other place in the world where you have that world-class solar resource and within reach of transmission access to huge load centers in California, so this is one of the best places in the world to put renewable energy,” Eddy said.

With about 1,500 acres needed for each tower and heliostat field, Sandstone will be a 15,000 to 20,000-acre site; just 0.03 percent of the federal lands in Nevada, but on a scale of electricity generation with the Hoover Dam, Nevada’s other gigawatt-scale renewable generation.

The two sites that SolarReserve has narrowed the search down to are in Nye County, like Crescent Dunes. 

“We’ve probably looked at 15 or 20 different sites over the past 18 months, and we’re now focused on two sites that we think are a good fit,” Smith said. He expects to choose and to begin the permitting process in six months. 

Solution for California’s Duck Curve

According to Karim El Naggar, chief digital officer for GE energy connections, a major driver for storage comes from the growth of daytime solar PV, time-shifting demand into the evening hours.

“The duck curve is a big problem today, and it’s going to be an even bigger problem because there are definitely more and more distributed energy resources among the generation that is coming into the grid, and it is coming in at a faster and faster pace,” he said. “I look at California as a peek into the future of many other places around the world especially in mature markets — developed markets, where more and more solar is coming online.”

Back in 2011, Smith had mentioned that their next CSP project in the U.S. would not be until “after 2020,” when the duck curve became more pronounced and California’s need for storage would be clear.

“We really feel the time is right. It will take about five years to develop and construct the first phase of the project,” he confirmed this week.

“It is now clear to regulators that California’s rising renewable portfolio standards levels will need a substantial amount of energy storage, and our view is that our molten salt technology is really the clear choice, much more cost-effective and environmentally mindful than trying to put a million batteries out there that will need to be replaced in 10 to 15 years,” Smith said.

California’s First Gigawatt-scale CSP

SolarReserve envisions 2021 for the first power delivery from the Sandstone Energy project, given the estimated five years to permit, finance and construct.

Construction would begin on the 2 GW project in two to three years and SolarReserve hopes to work with one of the big U.S. construction firms, such as Fluor, Bechtel or Shaw.

Due to the much larger scale, Smith expects substantial savings in supply chain capital costs compared to Crescent Dunes, which was “completely first of a kind and custom-made.”  

The Crescent Dunes project was selected as a finalist for Renewable Energy World’s 2016 Project of the Year Awards. Read more about the finalists and honorable mentions here.

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Susan Kraemer reports on renewable energy for CSP Today, Wind Energy Update, PV Insider and Renewable Energy World, and has written about renewables for Cleantechnica, Green Prophet and other sites.

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