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Published on August 29th, 2015 | by Susan Kraemer


Solar Opponents Win: Palen To Be Trough, Not Tower

August 29th, 2015 by  

According to a filing with the California Energy Commission (CEC) this week, Abengoa has apparently given up on attempting to permit what would have been California’s second concentrated solar power (CSP) project after Ivanpah to use tower technology.

In its latest iteration, this was to have been a 250 MW tower with storage.

Instead, in response to opposition, Abengoa will revert the plan to a trough project.


Image Credit: Brightsource Ivanpah

“In response to the concerns that have been raised, the Project Owner has determined that a solar trough project, similar to that approved in the original application for certification, will be pursued for this site, and the design will include energy storage,” the company said in its filing.

It’s a sad day for California, which had a chance at state-of-the-art advanced technology; tower CSP with storage, thanks to decades of investment in research by NREL and Sandia.

Workers at a

Image Credit: Google

As part of trying to stop Palen, a well-orchestrated media frenzy was created by opponents, centered on the supposed danger to birds at Ivanpah, and claimed 28,000 birds were killed by the project.

This opposition is directly responsible for Abengoa’s dialing back to less advanced technology.

NRG Energy as ⅓ owner was operating Ivanpah when thousands of identical stories made outlandish claims about avian mortality. Many began with this line: “Workers at a state-of-the-art solar plant in the Mojave Desert have a name for birds that fly through the plant’s concentrated rays….”

“Ivanpah is like a lightning rod for news,” former NRG Energy spokesman Jeff Holland confided at the time; astonished by the rancorous coverage. “Everything else is so quiet.”

In April of 2015, the actual first year avian mortality was estimated by HT Harvey (the environmental firm commissioned by the CEC to assess the project) to be at most 3,400, not 28,000.

With no count of the background mortality rate in an equivalent 3,500 acres next to the 3,500 acre Ivanpah site, there is no way to compare this estimate to background mortality rates. The CEC concluded: “Comprehensive Analysis of Ivanpah’s First Year Qualifies Avian Impact as ‘LOW.’ ”

But as soon as Abengoa’s filing appeared, the opponents started up again, on the CEC docket. This time, Abengoa cut short the circus, and after the first five comments on the Palen docket in response to its earlier request to extend the deadline so it could do the engineering design to add storage for the tower project, the firm threw in the towel.

Trough configuration had previously been approved for the Palen site for Solar Millennium, which was bankrupted by the PV price wars in 2011. Abengoa together with BrightSource (as Palen Solar Holdings) bought the permitted site, and had planned to build a 500 MW tower CSP project.

After a long and contentious permitting process, a 250 MW tower with storage appeared to have a way forward, and BrightSource sold its share to the older firm, Abengoa, which has global experience building CSP towers with storage.

Tower is best for storage

Storage is the reason we need CSP. There’s plenty of cheap PV. It does a great job — in the daytime. But to fully replace carbon combustion, we need a solar technology for nighttime too.

Trough is the older technology. Because it uses oil as the heat transfer fluid, it has to sort of “bolt-on” molten salt storage. The hot oil has to go through a heat exchanger to store the heat in tanks of molten salts, ready to boil water to make the steam to drive the turbines when needed.

And since the hot oil is run through miles of pipes out through the solar field, it can’t get to the high temperatures and efficiencies of tower CSP.

Tower is the advanced CSP. It is inherently much more efficient in enabling storage, because the same molten salts circulating up and down the tower can also be stored in tanks for use when needed.

For these reasons, tower — with molten salts — is the obvious choice if you want storage. And California wants storage.

Thank you Jimmy Carter

Image Credit: io9

Instead, the state will now get older trough technology developed in the Carter era, not designed to include energy storage.

The first trough plant, SEGS, was built before storage became a necessity. Its developers were bankrupted by the abrupt repeal of Carter’s advanced energy incentives when the Reagan administration went back to backing fossil fuels.

Like the other nascent solar technology of the time (PV), CSP was then driven from America. While PV went to Japan where Sharp and Panasonic grew to become the first major solar panel makers; CSP went to Spain, and Spanish firms became world leaders in trough CSP.

With generous government support once again advancing clean energy technologies, two California tower CSP developers (SolarReserve and BrightSource), were able to find investors.

BrightSource developed the 377 MW Ivanpah tower CSP in the Mojave desert and SolarReserve is now commissioning Cresent Dunes, the 110 MW tower with 12 hours of molten salt storage at Tonopah.

Despite starting a decade after Spanish CSP, tower bids are now as likely to be awarded to these two US startups globally as to the now well-established Spanish CSP industry.

BrightSource is developing tower projects in Israel and — with storage — in China.

SolarReserve has a 6 GW global pipeline and is developing tower projects with 12 hours of storage in South Africa and with 24 hours of storage at Copiapo in Chile.

But back home in their native California? Just more trough. Thanks, solar zombies.

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About the Author

writes at CleanTechnica, CSP-Today and Renewable Energy World.  She has also been published at Wind Energy Update, Solar Plaza, Earthtechling PV-Insider , and GreenProphet, Ecoseed, NRDC OnEarth, MatterNetwork, Celsius, EnergyNow, and Scientific American. As a former serial entrepreneur in product design, Susan brings an innovator's perspective on inventing a carbon-constrained civilization: If necessity is the mother of invention, solving climate change is the mother of all necessities! As a lover of history and sci-fi, she enjoys chronicling the strange future we are creating in these interesting times.    Follow Susan on Twitter @dotcommodity.

  • Similarly, weren’t there windmills in Holland in like the 17th century. Even run-of-the-river pumped hydro was essentially what drove water wheels using gravity since the somethingth century.

    But SEGS was the first developed at commercial scale (354 MW) in the US, that was the beginning of the solar thermal industry.

  • cumfy

    The most significant problem with tower CSP is the very low energy density.

    Trough is significantly superior here.

    I use to think CSP would prevail, but it is clear PV and EV battery storage will win. Does anyone still think CSP will be big ?

    • PV and batteries are our best option for rooftop and vehicles, but at grid scale needs, would you rather spend $500 per kilowatthour of storage or $30?

      Per the DOE, that is why they think CSP (tower) is a better bet for storage at the grid scale. CSP storage at $30 is already an order of magnitude cheaper than $500 or if batteries cut their costs by 50%; $250.

      And there is no life cycle limit with CSP storage because you’re just rolling molten salt into huge tanks.

  • eveee

    Right now solar diminishes the market for storage. Until there are sufficient market mechanisms that reflect or anticipate economics for storage, economic demand will not drive it.

    So right now, CSP with or without storage is at a disadvantage with solar PV and wind, which displace fuel.

    The reality is, that while detractors have claimed storage, none is needed. There are already adequate reserves and plenty of gas turbines. With solar matching demand well, there is less need for gas turbines.

    It will take higher integrations before storage becomes useful.

    In fact, rather than needed for renewables, storage will displace gas peakers because of its unanticipated lower costs at this early stage.

    • Solar increases the need for storage. The more solar cancels out the afternoon peak, the steeper the ramp-up needed in the evening.

      • nakedChimp

        PV is just about to flatten the daytime peak and moving it into the evening – a peak being a high point with downward trajectories before and AFTER.. why would the ramp up to the evening peak get steeper if the level it starts from is becoming higher and getting closer?

      • GCO

        Yes, the CAISO has made dire predictions for some time… which have failed to materialize so far.

        And btw, even them don’t advocate for storage (at the grid level), but more flexible generation instead (which, granted, could be CSP with storage). Demand management IMHO would be the other side of that coin.

      • eveee

        Total energy stored is reduced. The number of total kwhrs of storage is lower. In Germay, pumped storage is being shut down or running on reduced margins only a few days a year.

        Read about it here.


        The day/night energy storage arbitrage would give 8 hours of peak storage at high amounts, including some early evening.

        All that is left is the fewer and smaller early evening storage, the ducks head. Its lower than the daytime peak load.

        The ramp can be handled by peakers or storage. Since batteries are better than gas peakers at this, and market penetration is low right now, you have a point.

        It won’t slow utility battery storage market penetration one bit.
        Just look at Teslas PowerBlock. 610 million in orders in 7 days.

    • globi

      I agree, there’s no need for storage.
      Even during maximum solar production in Germany, the coal power plants produce more power at noon than at midnight.

      Also, why 0.25 GW of solar power in Southern California would need storage is not clear to me anyway. Since Southern California is already interconnected to the BPA in the Northwest which has 15 GW of flexible generation on tap. http://www.bpa.gov/news/pubs/GeneralPublications/gi-BPA-Facts.pdf

  • vensonata

    So, the final estimate is 1 bird per acre per year. Jeez. Natural mortality has to be at least that. So maybe it is actually making birds live longer! Anyway, these bird mortality solar/wind turbine stories seem strange when Americans are eating 9 billion birds per year! I had to read that number twice on wiki to believe it.

    • Brett

      Never mind the number of birds killed every year by domestic cats. Those things are cute little murder machines.

      • dRanger

        This situation might lead us to think that maybe this opposition is not really about birds at all. But what else could it possibly be?

        • eveee

          Astroturf with other interests backing it in the shadows?

          • dRanger

            Well, when something doesn’t make sense it’s often good advice to follow the money. I would feel that the protests were more honest if they protested tall buildings and cats with proportional vigor.

          • eveee

            Yes. Nobody is calling for equipping all cats with bells and limiting eliminating tall buildings. One more, cell phone towers. Everyone turn in your cell phones. We are going back to land lines. And no more power lines, either. Its ridiculous.

          • Kevin McKinney

            Of course you are right. If they cared about the birds, they’d start with the biggest threats. It’s all crocodile tears.

          • Bob_Wallace

            You’ve got a spelling error in your last sentence. It should be –

            “It’s all Kochodile tears.”

        • Bingo

        • Brett

          @disqus_5J3ahCwism:disqus Sinister cat cabal with interests in fossil fuels. They don’t like CSP eating at their profit margins, or over cooking their snack food.

          • dRanger

            Yesssss…it’s all starting to make sense…

      • mike_dyke

        Didn’t someone cure this bird-killing problem a little while ago by altering the position of the mirrors when in standby mode?

      • Alastair Leith

        These arguments are advanced by the same people who oppose feral cat controls on compassionate grounds.

        • Brett

          Which, what? How would someone oppose feral cat controls based on the fact that domestic cats kill animals?

    • eveee

      This and wind get all the focus for killing birds, but as you say, they probably lower the number of bird deaths.
      For sure, if you wanted to lower bird deaths you would use these instead of FF.
      Absolute instead of comparative thinking. The question should be how many compared to the alternatives.

  • Thanks for the excellent coverage, Susan. Sucks about the influence of those solar zombies, though. Personally, I would have hoped Abengoa had pushed through the nonsense, though.

    • Larmion

      Abengoa is the market leader in both designs and actually produced trough designs on a much larger scale. As such, I doubt they care much about which design they get to build.

      It’s California that loses out, not Abengoa.

      • I agree. A sad day for California. We coulda been a contendah!

      • Alastair Leith

        yeah capitalism is great lol

    • JamesWimberley

      The OP disses trough technology without strong evidence. The UAE, an autocracy which can ignore public opinion, chose it for the big Shams plant (link), presumably on technical grounds.

      Tower technology will only become clearly superior when the CSP industry cracks the Brayton cycle: direct heating of air to 1000 deg C in a ceramic receiver, then feeding it through a high-efficiency gas turbine. One big problem is finding a way to store heat at that temperature.

      • Larmion

        Shams does not include any storage, presumably because the NG-dominated power grid in the UAE is flexible enough to do without any. In that case, there is little reason to choose the newer, more expensive solar tower technology.

        California, on the other hand, desires storage (even though it is not yet strictly necessary). Solar towers can directly melt salt for storage and thus avoid the need of an inefficient heat exchanger to melt salt, as a trough system requires. This is explained pretty well in the article.

        As such, comparing Shams and Palen is a bit of a an apples-an-oranges affair.

        I’m looking forward to the completion of Noor in Morroco. Then we will have both solar towers and troughs of the same generation in the same location, both with storage. That’ll be the first truly meaningful comparison we have.

        • JamesWimberley

          Without data, I assume the UAE load curve is pretty much dominated by daytime a/c. Practically the only industry is oil & gas who burn their own stuff.

      • My strong evidence comes from about 4 years of frequent interviews with the industry and researchers at the government labs.

        What they say is that further advance is only possible with tower, which is why all their R&D (DOE, NREL, Sandia, ARPA-E awards) centers on tower.

        I should revisit some of these early R&D awards for Brayton cycle, Super-critical CO2, and see how they are going:

        • JamesWimberley

          You provide an argument that R&D should go to tower. Fine. That’s not a reason for preferring it strongly today. The extra stage of heat exchange can’t be that significant: you have to put in a heat exchanger to get the heat out of storage anyway.

          • Yes, I agree. Partly because CSP can only be built at utility-scale – and ideally around 100 MW per tower, it hasn’t had the numbers of projects needed to come down in cost as fast as PV.

            Yet, just a few years ago, Abengoa’s trough with storage was 21 cents a kWh, and their most recent tower with storage in Chile is 11.5 cents. SolarReserves’s first tower/storage was 13.5 cents in NV in 2009, and their second, awarded in January was 12.5 cents in South Africa.

            So slowly but surely, in time for the 2020s…

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    • Miller Plant

      Didn’t Nikola Tesla propose the trough type solar concentrators in the
      Electrical Experimenter, March 1916 on the cover story “Utilizing the
      Sun’s Energy”, and not in the “Carter Era”? peswiki com/images/7/73/Tesla_Solar_Electrical_Experimenter_p2_crop_800 jpg

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