Published on May 4th, 2013 | by Zachary Shahan


Eos Energy Storage — Next Big Thing In Energy Storage?

May 4th, 2013 by  

We’re creating a resource page on some of the most standout energy storage options moving towards commercialization. If even one of these technologies makes it to market with the specs claimed, it could change the energy game. Let’s hope that happens.

The first article in this series was about the zinc-iron redox flow batteries Zinc Air Inc. has been developing under the radar up in Montana. In this post, I’ll delve into the claims Eos Energy Storage is making about its own zinc-based batteries, which are initially being targeted for grid storage application.

The battery Eos has been developing is a zinc-air battery, which would probably draw some flags for you if you keep up with this sector of cleantech in a bit of depth. Zinc-air batteries have a number of shortfalls that make them less than ideal for grid storage (i.e. cycle life and efficiency issues). However, in a presentation about Eos that I watched last year (sorry, the video doesn’t seem to be online any longer), the claim was that the company’s zinc-air batteries were nothing like conventional zinc-air batteries — that they had built the batteries from the ground up in a completely different way than was previously done. As far as I know, the details of that are under wraps at the moment, but if you have specific questions, I’m pretty positive we could get folks from Eos to answer those in the comments below.

Based on publicly published documents for its grid-storage battery (the Eos Aurora), Eos is presenting cycle life, cost, and efficiency data that puts its technology in very good light.

As you can see in the image below (click here to see a larger version), the claimed cost is $1,000/kW or $160/kWh, the cycle life is 10,000 full cycles (30 year life), and the storage system has a 75% round-trip efficiency. And, as such, the LCOE is very competitive.

eos aurora

Regarding commercialization, here’s a quote from a document shared with me by one of our dedicated readers: “Eos plans to commercialize its first-generation 1MW/6MWh grid-scale storage product in 2014. This containerized battery can be deployed across the entire electric supply chain and scaled from small building to utility-size applications.”

Eos is currently scaling up prototypes of its battery technology (5kW/30kWh units). They are to be manufactured this year, and are to be delivered to customers in early 2014.

All well and good, if the technology does indeed come to market as laid out — with the specs above — and without any significant drawbacks unmentioned by the company.

Eos Is Bringing In The Money, 1st Partnership Set

As a vote of confidence, Eos notes that one of the largest utilities in the US led a $15 million Series B financing round that was closed in 2012. “Eos is in the midst of its $30M Series C round to support the company’s ramp-up of manufacturing capacity,” the company adds. Furthermore, “Eos has joint development agreements in place or pending with a Top 10 global chemical manufacturer and a leading engineering and manufacturing firm.”

In a more recent public presentation, it stated that it would “develop 100s of MW of energy storage projects through its Genesis Program and through strategic partnership with Convergent Energy + Power.”

Other Eos Battery Benefits

A few more key selling points are that the Eos battery system is “safe, reliable, non-toxic, [and] non-combustible.”

And one more thing that sets the Eos battery apart is that it could be applicable in the electric vehicle market, as well as the grid storage, industrial, and commercial markets. For the EV market, it says it has developed a 70kWh battery that is capable of getting over 350 kilometers of range for $10,000. However, it is initially just starting commercialization of its grid storage battery, the Eos Aurora.

Eos Wrap-up

That’s quite a host of claims. It’s hard to get super excited about any non-commercial technology these days, especially when the claims are so big — many things look promising in the lab but don’t come out as hyped when they hit the market. But, aside from no one else cracking the zinc-air code in the way that Eos claims to have done, I’m not seeing any big yellow or red flags. (Let us know if you see any.)

EOS Aurora battery

The Case For Cheaper, Better Energy Storage

As we’ve reported several times here on CleanTechnica, demand for energy storage is increasing and the market is projected to skyrocket in the years to come. Energy storage will help to integrate more renewable energy into the grid when it matures enough that it is creating excess generation (which already beginning to happen in some regions). But, even beyond that, our grid and vehicle infrastructure have been greatly overbuilt in order to deal with our lack of competitive storage technologies. As old power plants come to a close, it would make sense to refrain from overbuilding and simply build more energy storage capacity… if competitive energy storage technology is on the market.

Regarding the above, here are a few interesting images and stats from Eos:

world energy storage

world energy storage capacity

energy storage market potential

More Info

For a lot more information on the Eos zinc-air batteries — as well as its EV battery and white goods market strategies — check out the full public presentation thar Eos released in February.

Check out our new 93-page EV report, based on over 2,000 surveys collected from EV drivers in 49 of 50 US states, 26 European countries, and 9 Canadian provinces.

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About the Author

is tryin' to help society help itself (and other species) with the power of the typed word. He spends most of his time here on CleanTechnica as its director and chief editor, but he's also the president of Important Media and the director/founder of EV Obsession, Solar Love, and Bikocity. Zach is recognized globally as a solar energy, electric car, and energy storage expert. Zach has long-term investments in TSLA, FSLR, SPWR, SEDG, & ABB — after years of covering solar and EVs, he simply has a lot of faith in these particular companies and feels like they are good cleantech companies to invest in.

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  • Hank Wilcox

    You guys are a little slow on the uptake. A young lady named Eesha Khare has just obsoleted all storage tech and seriously changed the game with a simple capacitor technology. It’s interesting, how so few people realize that if her device can be made affordably and to scale, it will easily change EVERYTHING, and for the better. The problem with manufacturing dirt cheap electric energy has always been storing and transferring it efficiently it to when and where it’s needed. She could send us back to the fifties on fuel and energy cost and usher in a new age of prosperity for all. Hilariously short sighted is her getting “second” prize! for her invention. That’s like getting the consolation prize for Einstein’s Atomic Theory.

    • Bob_Wallace

      Could be that you are a little quick jumping the gun.

      There’s nothing new about supercapacitors charging very quickly. That’s simply a characteristic of supercapacitors. And they are good for hundreds of thousands of charge/discharge cycles.

      Supercapacitors would be the perfect storage medium – if they held enough charge per volume/weight. Existing supercapacitors have energy densities that are approximately 10% of a conventional battery.

      I see nothing on line saying that Eesha has invented a supercapacitor that stores as much energy as do batteries.

      You got any capacity stats?

      And I see a claim that her supercapacitor can last 10,000 cycles. Supercapacitors are good for more like a million cycles.

      How about we hold off on the celebration until we find out how much energy her device holds? And if it will actually perform thousands of cycles without failing. There’s a lot of rough road between something that looks promising in the lab and something that delivers in the real world.

      • Josef V.

        20.1 wH/kg, though I suspect that is without proper encapsulation, which would cut it by a fair amount (30-50%.

        • Bob_Wallace

          Lithium-ion batteries are around 150 Wh/kg.

          Going with SCs in a cell phone would mean having to charge several times per day, perhaps as many as 10x, rather than once.

  • Hmm – don’t believe the numbers above. Looking for the source it seems the EOS data reported is actually ‘recycled’ from a December 2011 white paper found here:
    So it seems they are two years old, and possibly not accurate for December 2011!

    First does EV storage count? Back of the envelope – someone check my calcs, its late!

    50000+ Nissan Leafs on the road with 24kWh/90 kW Li ion battery = 4500 MW storage

    Now > 5 million Toyota hybrids (incl Lexus) and rough estimate av 4 kW batteries nickel metal hydride = 20 000 MW storage

    ok – even without EV storage market – or perhaps the possibility of some error above on my part:

    BYD alone now has a range of storage and installed a 100 MWh Fe phosphate storage in China last year

    According to BYD company data, BYD manufactured 100 MW storage in 2010, 600 MW storage in 2011, and 1200 MW storage in 2012.

    • Lin

      Utility companies have made this aware to government authorities, that houses that had installed renewable energy to the grid on the rooftop, are now consuming more energy than before.

      • Adam.T

        Yes that right, but there no requirement to reduce energy by any amount under the law, even with rooftop grid solar power system installed you can use as much coal fire energy as you like because its free, with out having any accountability for that Co2 emission produced.

  • Breath on the Wind

    Energy Storage is a growing area that deserves your closer examination. EOS has been around for a while and seems to have a flow battery as well as their zinc-air model.

    At some point we will have to recognize that not all grid storage is created equal. Flywheels like those created by Beacon Storage and someday ultracapacitors represent the fastest times for frequency regulation. New laws make this the highest paid energy storage. Next will come battery systems that provide intermediate storage times at an intermediate price. At possibly the cheapest prices and with the longest response times will be thermal and mechanical systems such as pumped hydro and various thermal batteries like molten salts used with CSP systems, an interesting reversed heat pump application, and chemical thermal batteries:

    CAES systems suffer from inefficiency due to energy lost when compressing air and like pumped hydro siting problems. It is interesting to hear of a heat capture addition to these systems for increased efficiency. Enjoyed reading your article and looking forward to more.

    • Dave2020

      A fair appraisal and a breath of fresh air, but “longest response times” is incorrect. The other factors are location, and choosing the best option for each renewable – ‘horses for courses’!

      Battery storage – good to go with PV.

      Thermal storage – a natural match with CSP. NB: This is ENERGY storage before-generator. There are in effect NO round trip losses, so in comparison to electricity storage it has a RTE of 100%. There are lower demands on grid capacity and transmission fees for ‘wrong-time’ electricity fall to zero.

      “at high penetration levels CSP with TES can be despatched to displace natural gas.”

      Mechanical storage (such as pumped hydro or MIT’s deep ocean sphere) is a natural match with the kinetic renewables – wind, wave and tidal – but only if it’s used before-generator. Obviously, existing systems are being located after-generator, which is very wasteful.

      For bulk storage and compared on an ESOI basis, batteries need a 20-fold improvement to compete with mechanical storage. This is largely because of duty cycles and the longevity of infrastructure build.

  • Bob_Wallace

    The storage industry made such a smart move when they adopted “shipping containers” as their basic building block. Fill a container with batteries and electronics at the factory. Create a ‘plug and play’ storage unit in a weather tight package. Load them on a normal 18 wheeler and truck them to the site.

    Set them down on a concrete footing and hook them up. Cranes that can lift a container off a truck are easy to come by.

    Most cities have old industrial sites which are sitting unused. Most of those places are not going to have neighbors who would complain about some ‘shipping containers’ piled up on the grounds. And there are probably large transmission wires already in place.

    Unlike a new pump-up, permitting should be a piece of cake. No pristine land is being disturbed. No environmental study should be needed.

    Installation should be days, short days, and not years. Real estate (brownfields and landfills) should be cheap.

    If a unit needs extensive repairs it can be trucked back to the factory and a replacement unit set in its place.

    Storage could even be moved from one area to another if needs shift.

    • SecularAnimist

      Yes. Moreover, in addition to a variety of battery technologies, other storage technologies — I’m thinking of flywheels and fuel cells — could be packaged the same way. Once you have industry-standard form factors and interfaces, shipping-container storage modules could be swapped in and out, and it wouldn’t matter that much how they stored electricity internally.

      What we also need, is similar “black box” storage units about the size of a refrigerator that can be easily installed in residential basements. Of course, what I mean by “we need” is “I WANT ONE”.

      • Bob_Wallace

        A company called LightSail is developing a compressed air (CAES) system in a container.

        Their approach is unique in that they claim they can capture the heat created when the air is compressed and then use it to re-warm the air when it is used to spin a generator.

        It’s going to be very interesting to watch as different companies and technologies fight it out for industry dominance. It might well be that some approaches are best for the daily “heavy lifting” and others will provide the cheapest long term storage to get us through the lowest supply times.

        LightSail, for example, is probably not a good long term (>1 day) solution. They can store the heat for only so long whereas batteries should hold charge a long time.

        • Andy

          All these claims made here are futuristic and never will eventuate.

      • dcard88

        Did you miss this line in the article?:

        Eos is currently scaling up prototypes of its battery technology (5kW/30kWh units).

  • Bob_Wallace

    $160/kW and 10,000 cycles would get us into the 2 to 3 cents per kWh range. A bit more with balance of system costs (real estate, maintenance crew, etc.).

    If EOS can give us storage at that price then the last piece of the puzzle is in place.

    Let’s say we get 50% of our electricity directly from wind at 5c/kWh. 20% directly from solar at 7c. 10% from hydro and geothermal at around 7c. The last 20% stored wind at 5c + 4c.

    (0.5 x 5c) + (0.2 x 7c) + (0.1 x 7c) + (0.2 x 9c) =6.4c/kWh

    We can live with that. And the generations following us can live a lot better if we do.

    • Jenny

      Overlooking both calculations put forward here, I believe that figure is not right you failed to anticipate system failure costing which occurs in most renewable energy systems, this have to be factored in the costing. I anticipate that this will be more than three times that calculation for profit.

    • Jim

      Hi Bob
      I don’t see that happening any time soon in Australia, but I think that people living in remote area should be rewarded for the there efforts for C02 reduction like a discount on solar panel or battery.

      Recently there was a media report in the media that people were installing all air conditioning systems after receiving subsidies for roof top grid connected solar power systems, the utilities companies came out and stressed the importance of not installing more air-conditioning. Electrical commission informed of the costing for every air-conditioner installed on the network was costing the system over $10,000 in utility upgrades to the poles and wire network. People should be forced off the grid if they want to use solar power.

      • Bob_Wallace

        “People should be forced off the grid if they want to use solar power.”

        That makes no sense to me. If some people put solar on their roofs the end result will be that the cost of electricity will come down for all. As we have seen in Germany even a modest amount of solar destroys the daily peak when highest priced electricity has to be purchased.

        Probably all countries are going to have to struggle to move from fossil fuels to renewables. Companies that own thermal plants and coal mines are going to fight very hard to slow the process as much as possible. They are looking at stranded assets and big losses.

        Germany just fought back an attempt by pro-fossil fuel interests to limit renewables. We have those battles ongoing at the state level in the US.

        Australia seems to have its own peculiar growing pains which seem to be compounded by a number of whackos who believe and propagate weird misinformation. Hard to tell if they are fossil-fuel industry employees or simply people who stayed out too long in the midday sun without proper head gear.

        • Zoris

          I’m not sure where you getting that information, but Australian Germany have one of the highest electricity cost in the world, even Lord Monckton is implying that Grid renewable energy is a scam it does nothing to alleviate greenhouse gases nor bring down the cost to the consumer.

        • ChristianHJW

          Bob, sorry, but as a Hardliner i do agree with Jim to some extent. It is highly unfair to mount PV cells on your rooftop, combine it with a pack of batteries (and even subsidized, like what is happening here in Germany now), produce 70-80% of your own electricity – so far, so good – and then rely on the public grid, financed by all the others, for the rest 20 – 30%.
          People have to understand in near future that safety of energy supply is a common good, and of very high value even, and as all common goods they have to pay for that !
          With the 20 – 30% power which they buy from the DNO, they don’t even cover half of the cost which it takes to keep up the lines operating that they are using !
          Here in Germany we are therefore discussing already to change the pricing System, and charge everybody a general connection fee, irrespective of the amount of energy which they are using, as soon as they are being connected to the public grid, and do enjoy the safety of supply from it.
          Best Regards from Germany
          ROTOKINETIK UG (in foundation)

          • Bob_Wallace

            Obviously those who use the grid for their last 20%/whatever need to pay for what they obtain, and that includes the cost of keeping them hooked up.

            At the same time everyone else needs to acknowledge and compensate them for the value they deliver to the grid.

            They take load off the grid, especially during the hours in which generation cost are the highest. Supplying peak electricity is expensive. If enough people quit using peak hour power then utilities will be able to dispense with their most expensive inputs.

            They put “cheap to the grid” power on the grid during the highest demand hours. Again, this reduces the amount of expensive peaking supply the utility grid has to purchase. Non-solar people enjoy cheaper peak hour electricity.

            They should pay for the wires running to their house. But they should also get credit for when they use those same wires to supply cheap power to the grid to the benefit of non-solar end users.

            And I’ll make one more argument in their favor. The times at which solar-people will be reaching for that “last 20%” will likely be when late night wind generation is looking for a market. Boosting demand during late night (in the US at least) would increase the profitability of wind farms. More profits = more investments and more turbines installed. More turbines installed = more inexpensive wind on line during higher demand hour.

          • ChristianHJW

            Bob, the main cost for the operation grids are the deprecation of their investment cost. Your argument would only be right if it was guaranteed that the effect of taking load off the grid from the PV people would be guaranteed, but this is not the case.

            The grid has to be designed and built for a ‘worst case’ scenario, and this is for a cold winter day with no sun, no light, no wind and very low temperatures. Even on such a day the lights are not allowed to go out, or even worse, ESPECIALLY on such a day people need power desperately, as the heating systems in their houses will depend on that.

            The effect you are mentioning has currently only one (bad) effect, and that is that the owners of pumped hydro plants in Germany can not get the revenues they need to operate them successfully. The ‘noon peak’ is totally covered from all the PV cells feeding their power in just at that time, prices drop, and the business model of pumped hydro almost collapsed because they can’t earn money during that time any longer. OK, this is certainly not the fault of the PV cell owners, but besides the Billions of subsidees we were pumping into their operation here in Germany, we now have another problem to tackle, being how to support the pumped hydro plants, to a point which could even encourage new systems (or alternative technologies, like CAES, THES, TEES, PHES, etc.) to be built.

            My opinion is, if we would invest all these Billions of Euros into additional wind capacities and proper energy storage (BTW, i even consider a modern, high efficiency gas peaker a form of electrical energy storage), we would definitely be further ahead with the German ‘Energiewende’, no doubt. Germany is not a PV country, and will never be, we simply don’t have enough light. One Professor here has calculated that, if we should demount all our PV cells, trasnport them to Greece and erect them there, we could get the same ROI on our PV cells, and the excess energy alone would help the Greek to pay for their debts automatically 😉 ….

          • Troy

            The biggest controversy in the world and that Question is that was asked in Australia “was grid connected solar power real energy” according to the experts, “No grid solar energy does not provide real base load energy as we know it” basically no. Grid solar energy it has no storage capacity to provide, and for instance could not provide energy to start an air-conditioner and that’s where the problem lies is no energy in it.

            On the radio a challenge put forth to the infrastructure, a test was to shut down a street which had installed all grid solar power capacity and run the homes directly off the grid solar power with a small input of grid main power to assist the grid inverters to stay on, in that street which tried the test the system collapsed to even the grid inverter blowing up. The whole street became a dead short, providing proof of solar energy is a failure cannot provide base load energy to the household or the network.

          • Bob_Wallace

            The challenge was totally bogus. No one suggests that we would attempt to run a grid with nothing but solar power or nothing but wind power or that storage wouldn’t be needed.

            Take this challenge. Run a town only on the power from a single nuclear reactor. Watch what happens when that reactor shuts down for refueling or maintenance.

            I get the feeling that you don’t quite grasp how grids work. “no energy in it” was the clue….

          • Alfred Pemberton

            I will be trying the procedure which Troy posted and I will let you know the results as soon as testing are completed on a small scale. I will try the procedure with a small load air-conditioner to see if possible to run a direct load off the grid solar array inverter with a small bias main power applied to the grid inverter keeping inline with the posting literature experiment.

          • Bob_Wallace

            Don’t bother reporting back your results. Whatever you find has zero relation to how grids work or how we might develop our future grid.

            Why don’t you put your time to better use and learn something useful?

          • Franz

            Many companies are turning to battery storage as grid solar power cannot uphold power levels, I think they made a big mistake when they set up renewable energy and over looked the fact this would happen. On the other hand Germany is fast tracking 30 New Coal fire power generator station to be built, wind and solar power is not working to secure power needs nor could supply energy when the elements are against them.

          • Bob_Wallace

            Franz, I think someone has fed you some very faulty information.

            Your claim about grid solar power is simply false.

            And I’ll need to see some proof that “Germany is fast tracking 30 New Coal fire power generator station to be built”

            Here’s what I believe to be the facts…

            Germany’s new coal burning plants are replacing (not adding to) the older plants that either have been or will soon be decommissioned. Construction on those plants was begun before the decision to close nuclear plants was made and before large amounts of wind and solar were planned.

            By 2020, 18.5 gigawatts of coal power capacity will be decommissioned, whereas only 11.3 gigawatts will be newly installed.

            Furthermore those plants will be more efficient, releasing less CO2 per unit electricity produced than are the ones they are replacing. And the new coal plants are partially load-following.

            Now, one of us is clearly wrong. Feel free to bring your facts.

          • Jasmon

            You can find the information in the German news paper.

          • Bob_Wallace

            I don’t read German and I don’t know which papers are reliable and which publish junk.

          • Jenny-for-Green

            I would like to see the results of this please report back.

      • Ronald Brakels

        You’re a bit confused on this, Jim. Air conditioners contribute to peak demand – everyone turns on their air conditioners when it’s hot – and inceased peak demand can result in the need for expensive transmission upgrades.

        Rooftop solar produces electricity during our peak demand periods, which are when its hot and sunny, and so decreases the need for expensive transmission upgrades.

        • Dean

          The only person confused here is you, how air-conditioner could reduce peak demand at 6 PM and night with a reliance on solar energy, your blooming mad mate. More air conditioning installed requires more upgrade to the grid; it doesn’t work back to front with solar power mate. You can’t sit there and make claims that solar energy reduced peak demand its wacko tobacco talk, I suggest you stop smoking it.

          • dcard88

            In the USA, most companies turn off most equipment when their employees get off at 5pm, reducing demand so is transferred to resi use. Ron’s not mad and you’re a little harsh.

      • Jim, its the people using AC that is costing the $10k upgrade. Note the person who adds PV, they are reducing the upgrade cost, because less is needed to support the ACs during hot sunny days.

        • Viki

          It’s quite honestly don’t understand what you’re talking about utility solar power does not provide the energy requirements to run air-conditioners, your electric stove or central heating to even dishwashers including air compressors. Just one question to you, have you tried it, to run an air-conditioner off your grid invertor with out main power on?

  • arne-nl

    The Germans have constructed several dedicated pumped hydro facilities (as opposed to adding pumping capacity to an existing dam). The largest facility is Goldisthal, with a maximum output of 1060 MW and storage capacity of ~7000 MWh and a cost of € 623m. That works out to ~€ 90/kWh.

    Given the opposition from environmentalists(!) against the project, I doubt if any more dedicated pumped hydro facilities will be constructed as this offers an alternative that is about the same price per kWh (it will get cheaper as the technology matures), without the drawbacks of needing large areas of land, often in pristine wilderness.

    • Bob_Wallace

      I think Germany is looking at using abandoned mines for pump-up.

      And there’s the interesting idea of using an old open-pit mine in Canada for pump-up.

      But I expect batteries are going to dominate the storage industry. They’re so easy to site and to distribute where storage is most useful.

      Spread them around the grid and transmission costs are minimized. Charge them when demand is low, feed them out to the local community when demand is higher and smaller transmission lines are needed. Put them in remote wind farms and solar installations and spread flow over more hours.

      • Yes, even with mine you need to level split by height. Since you don’t want to pump water out of them into a river. There was a company for a while pushing the “idea” of hydro storage where they used under ground tanks. But don’t think they built any because of cost. I agree with Bob, when the cost of one/few of the battery approaches drop then you will see them spread out over the network.
        1) NRG producer site so can hold back NRG when wholesale cost is to low (free or negative at some times now)
        2) Large consumer to avoid their peak costs
        3) Consumers with PV to “bank” their NRG to be most cost effective.
        4) Nodes in the network to balance transmission congestion.

      • Ame

        California solar industry was on borrowed time with continuation of subsidisation leading to large debts in the country had to come to it’s end.

    • dwj

      At Goldisthal’s head of 302m, you need about 100, 40 foot container volumes of water to store 6 MWh. The active level in the upper reservoir seems to be about 24m or 10 containers in height. Thus you need a reservoir area of about 10 times the area of the EOS container for the same energy storage. If you assume some further access and cooling space around the container (more than 100 kW of air cooling), then the relative area is only perhaps 5 times or less. This is an area of reservoir in comparison with a parking lot of containers.

      Alternatively; Goldisthal’s upper reservoir area is 55 Ha and it stores 8.5 GWh. You would need 1416 of these containers to provide equivalent storage.

      Goldisthal was a very expensive development because it required taking the top off a mountain to create the upper reservoir with totally enclosing reservoir wall and underground power house. It is about as expensive a pumped hydro scheme as you could conceive.

      This sort of storage has its place but I don’t see it as competing with pumped hydro.

      • Bob_Wallace

        You say that Goldisthal was very expensive. Do you have a price per kWh?

        I’ve seen numbers around $0.02/kWh for pump-up. And the Swiss pump-up that had been planned and was just delayed/canceled was, I think, $0.06/kWh.

        If Eos turns out to be less than 2 cents per kWh it’s almost certainly going to win out over new pump-up. Building a new pump-up system, going through all the permitting stuff, is a pain.

        Utilities aren’t going to build pump-up unless it is clearly cheaper than other options. Plus there are large advantages in being able to distribute storage around the grid rather than having it centralized, perhaps some distance from point of generation/use.

        Pump-up can hold a lot of stored energy, but it can’t necessarily put a large amount of it on line at once. It’s better at very long storage.

        • dwj

          No, I don’t. It is just a judgement based on the complexity of the construction – way more difficult than just building a dam. Utilities have already built hundreds of GW of pumped storage all over the world and are continuing to do so. As the amount of renewables increases, the need for more pumped storage will become an imperative.

          The 2 cents per kWh is pretty dubious. It depends almost entirely on initial capital cost and interest rates. I think it improbable that 1416 of these containers, plus site costs and HV transformers etc. would be cheaper than Goldisthal. Keep in mind, the pump storage will last hundreds of years with turbine maintenance every few decades.

          Based on the data given, 1416 of these containers would offer 1416 MW of power. Goldisthal has a rated capacity of 1060 MW, so there is no great difference and Goldisthal could have been built with much more or much less power capacity, it just depends on how big you choose to make the penstocks and turbines. As for virtually every pumped storage scheme, generation is sized to give about 6 to 10 hours of operation. Most pumped storages can turn output from nothing to full in less than 1 minute.

          • Bob_Wallace

            Without firm numbers we are just guessing. I find the Eos <3c number at least slightly convincing since it's been thoroughly played with by a major grid and contracts have been signed.

            I'm not sure I buy your argument about building a new pump-up system being less complex than building batteries. In the latter case much of the work is automated and highly repetitive. A single factory can pump out the containers and ship them all over the place.

            Pump-up will probably have a higher interest burden. Money will need to be borrowed long before the plant starts creating revenue.

            And I'm not sure what "1416" has to do with anything. If the need is to get a lot of power on and off the grid in a hurry then batteries are likely to be a lot more efficient than pump-up. Each battery can take a full charge/discharge in six hours and all the batteries would be charging/discharging at the same time if needed. Pump-up maximum performance is limited by pump/turbine size. Reservoir size doesn't figure in.

            Batteries are at least as fast to respond as pump-up, if not faster. Both are fast enough that decisions won't be based on that parameter.

            Time will tell…

          • dwj

            You need 1416 (approximately) of these containers to provide the same amount of energy storage as Goldisthal. I just used Goldisthal as a point of comparison because it was mentioned in an earlier comment.
            Reservoir size (and head) is what determines how much energy is stored. It is the critical factor for any pump storage scheme as the sizing of turbines etc is based on emptying the reservoir in 6 to 10 hours. The turbines could be designed to empty the reservoir in 1 hour if there was a need for such super peaking capacity.
            Batteries are not more efficient than pump storage. Round trip efficiencies for pump storage are 75 to 80% (even better with modern variable speed machines) and efficiency and storage capacity do not degrade over time.

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  • Maybe a typo above “b” verse “m”

    “Eos notes that one of the largest utilities in the US led a $15 billion Series B financing round that was closed in 2012. Eos is in the midst of its $30M Series C round”

    Normally round C is bigger than round B, to be 500 times smaller is way past normal.

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