Tumblr Icon RSS Icon

Super Hot Salt: A Super Cool Solar Energy Storage Technology Innovation

By Climate Guest Contributor  

"Super Hot Salt: A Super Cool Solar Energy Storage Technology Innovation"

Share:

google plus icon

by Lauren Simenauer and Sean Pool, reposted from Science Progress

Policymakers and energy industry experts often talk about clean energy as though it isn’t reliable. In fact, while an MIT study recently found the existing grid would probably be up to the challenge of absorbing clean energy, intermittency does present a real challenge that renewables must address to get to high levels of penetration.

But BrightSource Energy, a major player in the market for concentrating solar power, or CSP, recently announced the installation of new thermal energy storage technology at three of its planned power plants in California. This thermal energy storage technology will go a long way toward solving the intermittency problem for concentrating solar power. BrightSource’s announcement demonstrates that we can in fact get reliable baseload power from the sun [or, even better, load-following power].

The thermal energy storage system, built using SolarPLUS technology, works by using hundreds of flat glass mirrors–called heliostats– to concentrate the rays of the sun, heating molten salts to several hundred degrees above the boiling point of water. The superheated salt is then stored in a giant insulated container. When the power plant needs to add additional output, it can use the heat stored in the molten salt to boil water to create steam to drive its turbines.

The added storage capacity will allow BrightSource’s new concentrating solar thermal power plants to continue producing electricity up to two hours after the sun stops shining. It will also enable the power plants to produce electricity at a steady and predictable rate throughout the day and will smooth out fluctuations that make managing solar power tricky for grid operators. Even better, the new thermal storage systems will allow the CSP plants to produce twice the electricity on the same amount of land as could be produced by traditional photovoltaic panels. This advance is yet another step toward the near future when solar energy can replace rather than simply supplement energy produced by fossil fuel power plants.

Adding this storage capacity to three existing plants will increase production by 4 million megawatt-hours, according to BrightSource. The company had originally planned to build seven plants at its location in California, but by applying storage technology, it discovered it could decrease the number of plants while producing more energy. The new plants are slated for completion over the next five years.

The deal is awaiting approval from the California Public Utilities Commission, or CPUC, which tentatively gave the green light to Pacific Gas and Electric to make a power purchase agreement with the Mojave Solar Project amid objections that the agreement would be too costly. But the CPUC has little to worry about with BrightSource and Southern California Edison. The technology BrightSource employs, which consists of mirrors and a water boiler, is cheaper and more cost-efficient than the older CSP technology that the Mojave Solar Project utilizes, and since the plants are air-cooled, they consume low amounts of precious desert water resources. By increasing storage capacity, BrightSource estimates it will actually lower costs for customers.

Additionally, the CPUC should approve the contracts because the deal is a natural consequence of a 2010 California bill, AB 2514, imploring the CPUC to determine good commercial targets for improved energy storage. The bill would hold the commission responsible for identifying cost-effective storage targets for power producers and then creating the appropriate regulations and incentives for storage deployment. BrightSource’s announcement of thermal storage technology shows the company is remaining a step ahead of the game.

Some environmentalist opponents object to the impact that the solar plants will have on Mojave ecosystems. But the storage technology will allow BrightSource to produce as much power with six plants as it otherwise would have with seven. The decision to scrap the seventh plant will translate to even more price cuts for consumers, as well as 1,280 acres of desert spared from development.

In what looks like a win-win for BrightSource, Southern California Edison, the environment, and consumers, solar storage is evolving from a distant dream to the reality of the present. Altogether the Ivanpah project will lead to 1,400 union construction jobs at peak construction, $650 million in worker wages over the life of the project, and avoid 13.5 million tons of carbon dioxide emissions. Said BrightSource Chief Executive John Woolard, “We came out very strongly with what I believe is the largest solar storage deal in the world.” If the CPUC approves the landmark contracts, the rest of the nation could also come out very strongly, as the region and the nation reaps the economic and environmental benefits of this new and dynamic industry.

Lauren Simenauer is a former intern with Science Progress, and Sean Pool is Assistant Editor of Science Progress. This piece was originally published at Science Progress.

Related Post:

Tags:

‹ CHART: Big Oil Backers Of Keystone XL Pipeline Gave Big To Senate GOP Allies

More Than Two-Thirds Of Western Voters Say Renewable Energy Will Create Jobs In Their States ›

17 Responses to Super Hot Salt: A Super Cool Solar Energy Storage Technology Innovation

  1. Mike Roddy says:

    I’d like to see some numbers on the current cost of molten salt storage. They have previously been all over the place, partly because there are several ways to calculate them: total cost per kwh, with or without rebates/subsidies, reduced transmission load factor, busbar or not, etc.

    It would also be interesting to see how CSP cost currently compares to PV utility plants. A price should be put on CSP’s ability to provide baseload, offsetting PV’s current cost advantage. This is also a complex exercise, since we don’t know if PV’s current depressed prices are permanent or indicative of a long term trend.

    We will need both PV and CSP, but cost information would be helpful here. Maybe you can provide some links, Sean- PPA’s are not transparent, and existing studies from two or three years ago are already out of date.

  2. fj says:

    Hot stuff, but a lot cooler than fusion to say the least; pretty close to liquid fire, but not anywhere near plasma . . .

    Intriguing

    And, likely very important transition technology considering it still seems we’re in a state of technological metamorphosis where mechanics is rapidly changing into electronics (and light) via insight by Hermann Minkowski early 1900s.

  3. Bill Woods says:

    “The thermal energy storage systems, built using SolarPLUS technology, work by using hundreds of parabolic mirrors to concentrate the rays of the sun on a tank of molten salts, heating the salts to several hundred degrees above the boiling point of water.”

    This doesn’t seem to be correct. Torresol’s Gemasolar plant heats the salt directly, but according to the source, BrightSource is still heating water, which is then used to heat “two tanks of molten salt [] placed at the base of its power tower.”

    “Adding this storage capacity to three existing plants will increase production by 4 million megawatt-hours, according to BrightSource. The company had originally planned to build seven plants at its location in California, but by applying storage technology, it discovered it could decrease the number of plants while producing more energy.”

    Four million MW-h per year, an average of 450 MW, is the total power of the six or seven plants — “the new set of agreements will provide approximately the same amount of energy annually but with one less plant”.

    I don’t see an explanation for the increased power per acre. Are they adding more mirrors to the collector field, or is generating power in the cooler evening hours notably more efficient?

    • Bill Woods says:

      There should have been a close-italics tag after ‘… while producing more energy.”’. Arrgh.

      What happened to the Preview feature?

  4. Leif says:

    Could pumped hydro from wind generation be used in conjunction with CSP to increase the steam pressure of the boilers or perhaps even direct induction heating of the salts themselves? Extending the night time productivity window and balancing out the wind production as well.

    • David B. Benson says:

      Much too expensive.

    • Bill Woods says:

      If you’ve got pumped hydro, you can generate electricity with very high efficiency, by running it down though the turbines. Using it any other way would be throwing energy away.

  5. KAP says:

    CSP has in the past been more expensive that PV even without storage. In fact, it’s fair to say that CSP is the most expensive energy source in the current mix. So adding storage is a technical advance, but it won’t help with deployment. And only deployment can save the planet.

    • Happy Heyoka says:

      Most CSP/Solar Thermal designs seem simple enough to build. I think any small town engineering firm that can weld steam pipe and polish metal could do it.
      Control system electronics are pretty cheap, widely available commodities. The salts themselves seam to be pretty commonly used in other industrial processes (= cheap). Steam turbines are a hundred year old technology, also well understood.

      You can’t say that for PV – sure you can assemble a PV system, but the most expensive bits (the panels) are essentially “magic” technology.

      Sure, PV is easier to deploy on your house or up to, say, 40kW – but for hundreds of multi-megawatt sized plants in less developed parts of the world, I think thermal plants might have an advantage.

      • Leif says:

        I believe you fail to see the value in distributed solar over the cost of infrastructure, and maintaining there of, required of distributed energy. With distributed solar a sunny back yard can become a cash cow. NO Middle men. Neighbors help neighbors and keep the profits at home. My 25K investment last year is expected to reap ~$1,500 in vacation money this year. How did Wall Street treat you.

        • Happy Heyoka says:

          I believe you fail to see the value in distributed solar over the cost of infrastructure, and maintaining there of, required of distributed energy.

          You’re labouring under the misapprehension that it must be either/or. And some basic regulatory and physics issues with the grid (…)

          My 25K investment last year is expected to reap ~$1,500 in vacation money this year.

          So you made $26.5k worth of power this last year? I want your feed in tariff… my 2.1kW system is good for about $200 a month.

  6. David B. Benson says:

    Unfortunately this is not solve the cloudy day problem. Solving that, and less expensive per kilowatt-hour would be a thermal store energized by an NPP. Unfortunately I know of no such arrangement anywhere in the world, but the engineering appears to be quite straightforward and entirely over on the conventional side.

  7. tim bastable says:

    Is the “2 hours after the sun stops shining” statement correct?

    Torresol are claiming up to “up to 15 hours operation without solar input” and are expecting to achieve 20 hours a day average production for the plant in Spain (http://www.torresolenergy.com/TORRESOL/gemasolar-plant/en) – 2 hours is a bit on the disappointing side by comparison!

    • Javier Kienzle says:

      That’s because the molten salt isn’t being heated directly, steam is heated directly and the molten salt tank is kept on the ground. The configuration provides more safety and reliability by not pumping the molten salt.

  8. Kevin Smith says:

    SolarReserve is building a 110 MW facility in Nevada right now and BrightSource hopes to start building one in acouple of years – about three years behind SolarReserve. SolarReserve’s technology has 10 hours of full load storage. BrightSource is hoping for 2 hours. I think you profiled the wrong company.

  9. Theodore says:

    To the young, all things are new.