Scientific American: Store Renewable Energy as Liquified Air

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Guest essay by Eric Worrall

Yet another renewable energy storage idea…

To Store Renewable Energy, Try Freezing Air

Such energy storage technology could help relieve congested transmission lines in places like Vermont

By John FialkaE&E News on January 2, 2020

The system that supplies clean electricity to Vermont is not exactly a model of Yankee ingenuity.

In 2011, the state adopted a plan to get 90% of its power from renewable sources by 2050. That led to a surge of wind-generated power from the northeastern part of the state and an expansion of solar.

But transmission lines in this sparsely populated part of Vermont have such low capacity that much of the renewable energy is often unavailable because the lines are too congested. The state was deprived of another form of emission-free power in 2014 when an aging nuclear power plant called Vermont Yankee was permanently shut down.

So what can Vermont do?

A British company called Highview Power proposes a novel solution: a storage system that uses renewable electricity from solar or wind to freeze air into a liquid state where it can be kept in insulated storage tanks for hours or even weeks.

The frozen air is allowed to warm and turn itself back into a gas. It expands so quickly that its power can spin a turbine for an electric generator. The resulting electricity is fed into transmission lines when they are not congested.

“Vermont has transmission issues,” explained Salvatore Minopoli, vice president of Highview’s USA affiliate. “It’s a situation that many places in the U.S. are dealing with where renewable energy is being deployed more and more. It’s power that’s intermittent. They need something to balance their system out.”

Read more: https://www.scientificamerican.com/article/to-store-renewable-energy-try-freezing-air/

Now we understand what happens when you put a humanities graduate in charge of rebuilding a power grid, what about this great new energy storage idea?

Liquid-air energy storage: The latest new “battery” on the UK grid

New energy-storage solution solves some problems but creates others.

MEGAN GEUSS –  6/13/2018, 10:00 PM

A first-of-its-kind energy-storage system has been added to the grid in the UK. The 5MW/15MWh system stores energy in an unusual way: it uses excess electricity to cool ambient air down to -196°C (-320°F), where the gases in the air become liquid. That liquid is stored in an insulated, low-pressure container.

When there’s a need for more electricity on the grid, the liquid is pumped back to high pressure where it becomes gaseous again and warmed up via a heat exchanger. The hot gas can then be used to drive a turbine and produce electricity.

Tesla’s new battery in Belgium shows value is in dispatch speed The system is called Liquid Air Energy Storage (LAES, for short), and if you’re thinking it sounds remarkably like Compressed Air Energy Storage (CAES), you’re right. LAES takes filtered ambient air and stores it so it can be used to create electricity later, just like CAES. But LAES liquifies the air rather than compressing it, which creates an advantage in storage. Compressed-air storage usually requires a massive underground cavern, but LAES just needs some low-pressure storage tanks, so it’s more adaptable to areas that don’t have the right geology.

LAES has also been compared to pumped hydro, where excess electricity is used to pump water up to a reservoir above a hydroelectric turbine. Pumped hydro and LAES both can be designed to provide power for hundreds of thousands of homes. But unlike pumped hydro, LAES doesn’t require a water system or elevation differences to operate.

On the other hand, an LAES system is only 60- to 75-percent efficient, compared to the 75- to 85-percent efficiency of lithium-ion batteries. Lithium-ion batteries can also respond to minute frequency changes on the grid almost instantaneously, whereas LAES systems deliver electricity by turbine, so their delivery response time isn’t as quick.

Read more: https://arstechnica.com/science/2018/06/liquid-air-energy-storage-the-latest-new-battery-on-the-uk-grid/

This energy storage idea in one form or another has been kicking around the UK for several years. The original incarnation of this idea was a compressed air storage system, but liquified air has advantages of compressed air. Liquid air containers don’t have to withstand extreme pressures, and a large volume of air can be condensed into a small volume of liquid.

The manufacturers claim the system is 60-76% efficient, which with other costs likely at least doubles the cost of renewable energy stabilised via this system. Probably cheaper than a battery, but likely still hugely uneconomical compared to fossil fuel.

There are also potential problems with reheating the liquified air in adverse weather conditions. Things could get very icy around the cold end of the reheater circuit. Highview claims to have a proprietary solution to the “waste cold” problem.

134 thoughts on “Scientific American: Store Renewable Energy as Liquified Air

  1. to be used when the transmission lines are not at capacity begs the question, is it needed then? And isn’t the real issue transmission infrastructure.

    • Sure, bruce, it is logical that the rural transmission line capacity should be increased in order to avoid the cases where demand in urban areas can’t be met even though there is supply from the remotely-sited unreliables. It would also make more sense that any sort of storage system would be centralized and close to the demand rather than smaller, less efficient, decentralized systems scattered across wilderness areas.

      However, the main root cause problem is intermittency and thus the need to have backup systems or storage systems. Fixing the transmission problem is necessary to be able to use unreliables, but not sufficient for a reliable power system. It’s a non-problem if you abandon the whacked idea of despoiling wilderness areas and massacring birds and bats with an unreliable power system.

      If intermittency is resolved by backup systems, they must be able to react extremely rapidly to changes in demand, i.e. be dispatchable, which practically-speaking means natural gas turbines or hydroelectric. But the greens oppose new hydroelectric dams, which in any case depend on suitable topology, so in most cases, you’re left with burning fossil fuels which is what you were building the bird choppers to avoid in the first place.

      That’s why they want storage systems that can be dispatchable and do not have CO2 emissions. But they can only get back 50-60% of the energy that they put into LAES. Also, let’s not forget that cryogenic refrigeration is neither cheap to build, nor to maintain. All of those costs, the towers built in wilderness areas, often requiring the building of new roads, the wind turbines that last for maybe 15 years, the transmission lines (new and upgraded), the storage systems, and the continuous maintenance of same, must be borne by the ratepayers.

      Or you could use natural gas to supplement whatever hydroelectric power you have, and build nuclear plants to cover base load.

      Of course if you realize that CO2 is not a problem, you can just burn whichever fossil fuel is most cost-effective and stop obsessing about the slight, temporary, largely beneficial warming that we have been fortunate enough to experience.

      • This scheme sounds interesting, but it does not solve the sun and wind intermittent problem as people do not understand how serious the winter problem is.

        The problem is the energy storage scheme must store massive amounts of energy for months, not hours.

        Wind and sun energy in the winter months is not sufficient to run a Northern developed country.

        The second problem is that there is not sufficient sun and wind gathering viable locations to power a country.

        Germany had reached that point where there where all viable wind and sun locations had wind and sun gathering equipment on them…

        … they ignored engineering reality, installed wind and sun in locations so that now their wind and sun is producing power at less than 20% of nameplate on a yearly basis.

        • My 3kW solar system here in Australia peaked at 120W on a cloudless summer day. Smoke has reduced visibility to about 1000m in my area. Not much sun making it to the ground.

          Fortunately the lack of sunlight getting to the ground means cooler temperature so no need for air cooling.

          Australia’s national grid is also under stress. Solar output is way down across most of the country. The 6700MW of wind capacity is producing 800MW. The main interconnector between the two larger states is out of action. Diversity of generating sources does not help at all if they are remote from the load centres.

          When Australia introduced the RET (renewable energy target) for the power supply system, I know for certain that no one considered the security implications.

          The broad extent of the fires might force governments back to basics; secure services rather than chasing fairy farts. Local government waste disposal and locvcal roads; state government secure water supply, electricity supply, main roads and sewerage; federal to oversee efficient provision and national security The country has wasted a huge amount of money chasing fairy farts.

      • Well they don’t just claim CO2 is a problem, they also claim non renewable resources are used too fast and will cause a crisis soon when they are exhausted.

        Then they claim that low interest rates mean we can “invest” in “renewable energy” devices and use precious resources to build those like there is no tomorrow…

      • Take a look at New Zealand ‘s electricity generation and distribution .
        We have plentiful hydro power in both Islands but over a third of our population live in the Auckland area in the North Island and less than a third of our population live in the South Island .
        A large power cable was laid across Cook Strait by a forward looking government back in the 1970s to bring power from the South Island Power schemes to our Northern population .
        All of New Zealands power generators are remotely controlled and it is very easy to turn hydro stations on and off as the load moves up and down .
        The Waikato River in the North Island has 8 power stations on it after it leaves Lake Taupo and the oldest station Arapuni was commissioned in the late 1920s so that it has been generating electricity for over ninety years .
        We also have a geothermal station at Wairakei near Taupo and several small stations in the Taupo region .
        I recently met a young engineer from Israel who was in charge of building a geothermal power station in Ngawha north of Auckland ( all components manufactured in Israel)
        A number of our power companies have installed wind farms and these are controlled remotely and when the wind is blowing constantly water is held back for the many times there is little or gale force winds .
        The nation grid works well as it was established by men with vision but now it all but impossible to get approval for even small scale hydro stations because the greens have an ideological hatred of damming rivers yet they love wind farms defacing the country side .
        At some stages our lakes and rivers supplying our hydro stations fall to low levels because of low rainfall but it can usually be managed as if one Island is dry the other has rain and at a last resort Huntly Power Station is started up which now mainly uses natural gas.
        A large block of power is used to supply the aluminum smelter at Tiwai Point in the South Island and there is a lot of agitation by greens and northerners to cancel the power supply agreement .
        Thats okay with me as long as all agree to never fly again in a air liner .
        Graham

  2. So, wouldn’t there also be some transport costs involved? Unless you’re going to make liquid air pipelines from source to destination.
    I think this might eat up any gains you might make from the system.

    • I believe the idea is toliquify, store and then feed to a turbine all at the same facility. No transportation of the liquefied air needed.

    • You collocate the liquefaction, storage, and regassification facility. Transport is measured in hundreds of yards, not miles.

  3. Math Physics, Economics, They are are a nasty bunch. So many beautiful and creative ideas get crushed by this trio of reality and they don’t care at all. They are completely unmoved by our tears. There is no point in fighting them. They are too strong and their endurance is eternal. It is better to learn how to work with them. They can be your friends or even your servants if you understand and respect them. Ignore their advice though and they will break you without a thought.

  4. Yikes!

    Baker Hughes (https://www.bhge.com/industrial/energy-storage/liquid-air-energy-storage) which is rep’ng this technology for Highview Power is estimating the all-in cost (operating, capex, maintenance, etc.) as $150-250/MWh.

    Using the a $200 cost, that’s $0.20/kWh! This alone would triple the non-distribution cost of energy in my neck of the woods before the cost-boost from the renewable itself!

    This is a meaning of “cost effective” with which I was previously unfamiliar……

    • You shouldn’t be using energy anyway MotO.

      Once carbon taxes raise the cost of fossil-fuel-generated electricity to around $2/kW-hr, this will be so much cheaper that they’ll have to impose taxes on it to keep government revenues stable.

      • My thanks for the reminder.

        I keep forgetting the hair-shirt, misery and deprivation future awaiting me.

    • Good Link,

      … and the cost of $150 – $250 per MegaWatt-hour assumes the scheme will be used for short term storage of electric power not storage for weeks and months.

      … there is no scheme which I know of that can economically used for electrical storage for weeks and months.

      …. as noted in my above comment, this scheme cannot be scaled up to store wind and sun gathering surplus electricity which is produced in the sunny summer months for use later in the winter.

      …. in the winter there are high pressure cold air masses that result in cold windless days that for a large portion of a month.

        • No, it shows the future of “Scientific American”, which is to continue to spiral down into anti-human sh*t spew. F**k them and f**k you.

      • “Vermont Electric … said that after three conversations with Highview, its LAES technology remains an “option.””

        Sounds like a LAES system hasn’t been *completely* ruled out, but it’s more likely going to be a large battery system, or just curtailment will turn out to be cheaper.

  5. This seems like a large capital investment to address shortcomings of power sources that are unnecessary and aren’t very good in the first. A lot of local waste heat will be generated and maintenance of pumps and exchangers will be a nightmare. Use is high humidity areas may be troublesome. Efficiency in cold weather will be poor, just when wind and solar also tend to be poor. My opinion is that it is a solution to a self-induced non-real problem.

    That said, these people should go for it (without government assistance). If it’s such a great idea it will succeed on its own. The technology is cool.

      • I guess that makes water “frozen steam”.

        …hmm it seems they just don’t make thesauruses like they used to.

        • Rocketscientist
          I think that thesauruses ‘went extinct’ during the early-Anthropocene. It has been speculated that it may have happened immediately after a bollocks impact cratered reading comprehension.

        • Is that why CCS schemes are financially unsound – too high a licence fee on compressing CO2 to a supercritical liquid at 100 bar+?

  6. Since politics is driving all this rather than economics, ideas that work poorly or not at all are mooted again and again with no consideration as to the experiences elsewhere.

    We begin with an unproven premise: “we must have ‘renewable’ energy!” and proceed from there. It’s hysteria.

    This is all going to end in tears.

  7. Problem 1) Cold things warm up, whether you want them to or not, the greater the temperature difference the faster they warm up.
    Problem 2) From the description, it sounds like they are chilling the air, and throwing away the heat. Then when they want the energy back, the absorb heat from the air causing the gas to re-pressurize. They then make use of this pressure to run a turbine. The idea that such a scheme is even 50% efficient is ludicrous.
    Problem 3) Heating enough liquefied air, fast enough to create a sufficient volume of high pressure air in order to turn a turbine. You are going to need a HUGE heat exchanger to do that. Especially in any region where relative humidity is above zero.

    • Pair it with a normal thermal plant.

      Most thermal plants are next to rivers so they can use river water to cool off the closed cycle steam generation. The warmed up water is returned to the river. It’s a major problem for trout streams because trout like very cold water.

      With proper engineering, the warmed up water from the thermal plant could be used to warm the LAES regassification process. The water returned to the river might even be colder than it was pulled out.

      • The normal thermal plant produces one hundred times as much energy, and needs many of these useless and inefficient units to make any difference. These are 5 MW units, with so little “storage capacity” that they won’t help at all.

      • In addition to keeping the cold air cold, you now have to build a system to keep hot water hot.
        More expenses, more places to lose energy.

        • As long as the wind and solar is surplus you could keep the heat pump going. As soon as power is needed the process reverses.

          I don’t think it’s ever been done, at scale, it won’t be done in Vermont, either.

      • Greg
        Yes, what happens to the local ecosystem when heat is alternately dumped into air or water, and periodically heat is extracted? I doesn’t seem that they have thought this through, nor anticipated unintended consequences.

        • Clyde, ‘haven’t thought it through’ and ‘unintended consequences’. I have been using these terms for a while now in regards to wind and solar power, they created a monster!

          I am not a scientist and so I cannot comment on whether or not this is a good idea, (though it seems like a bandaid for an open wound). Based on research I do however know that wind and solar renewables are not only superfluous, they are an ecological and economic nightmare.

          Have we not learnt anything from the whole wind and solar fiasco? It is unreliable, manufacturing, large scale transport (including the very trucks used to create them), don’t run on them. No one has yet come up with a viable recycling program for them! That in itself should put the breaks on any new technology. That is of great concern to me. What is going to happen to all that waste, and the toxic byproduct of recycling too?

          So yes my issue is, regardless of how clever the idea is, do we really need it?

          At the very least is it possible to restrict the global ‘rollout’ until it’s ‘thought through’. It sounds like it won’t work equally well in all parts of the world. Wind and solar hasn’t worked well anywhere but they’re still pumping them out. Why are we so eager to add to the waste disposal problems we already have.

          Wouldn’t be good if we could stop all wind and solar renewables and go back to fossil fuels till someone can come up with a solution that has been ‘thought through’?

          • Megs
            I sometimes wonder if those advocating these ad hoc ‘fixes’ are even capable of the necessary logical analysis to avoid unintended consequences.

      • The “efficiency” figures for LAES depend on not counting “waste” energy from a co-located plant as an input.

    • They completely swept the most difficult issue under the rug as if it does not exist.
      ” but LAES just needs some low-pressure storage tanks”
      …and a cryogenic thermal containment system.
      Oops did they forget that part? Sure the tanks can be maintained at low pressures, but only if you keep them at -196 °C. I the temperature beings to rise you had better allow for venting or your tanks will rupture. You’ll spend considerable energy merely to maintain the storage.
      This system is not new. It is used extensively in manufacturing where compressed air powered tools and equipment is used, such as aerospace manufacturing. Companies such as these have regular deliveries of liquefied air (mostly nitrogen at this point) pumped into large cryogenic holding tanks which feed control valve systems which expand the air and reduce its feed line pressure to the shop floor. Even the marginally insulated fittings accumulate large amounts of condensed ice on the external flanges and such, and this is in the rather arid dessert climate of southern California. (Anyone up in Seattle care to report on ice accumulation at Boeing?)
      Most of these renewable energy technologies are not new and have been refined for their effective niches ab serve their purposes well. As with most technologies they can function in “off prescription uses”, but not as well and often with cost prohibitive issues.
      Solar cells were invented for outer space, and they will work in your back yard…but more poorly and expensively than more attainable systems.
      Compressed air power is possible and may have use on a remote location where isolation makes transmission of inexpensive power more costly than this method, but scaling it up for mass usage would be silly. With the energy losses in each conversion: generator/motor/pump/tank/turbine/generator
      its not free. And you’d better try to recover some of the heat that gets “pumped” during compression and expansion or that gets tallied into the loss column as well.

      What has happened to the engineers?

      • Rocketscientist
        I remember that when I was a young man I often saw signs that said, “Six months ago I couldn’t spell enginear and now I are one.” Prophetic and pathetic.

      • Not to forget that LN2 tanks and pipes need to be vacuum insulated double-wall construction with vacuum pumps maintaining a high-grade vacuum. These systems are not low-maintenance!

      • What has happened to the engineers?

        They got woke.

        This system is going to have to have safety venting too or you’ve just made a very effective bomb.

    • Another problem. They go on and on about how this is a low pressure system.
      How the heck are you going to get a low volume, low pressure stream of air to efficiently turn a turbine?

      • The liquid air is pumped to a high pressure before expansion. The heat of compression is stored and used for expansion. In theory. LightSpeed couldn’t make it work.

  8. A couple of years ago PG&E recommended that we consider using dry ice to keep our food safe during prolonged PSPS’s. My sister in law followed this approach last summer. I guess she could of used frozen air instead. We used our Y2K vintage generator to keep the fridges cold.

    Given that 100% RE plans(1) call for a lot of over generation, and you can only store a limited amount of energy in batteries, than maybe one could get carbon credits from the frozen co2 in the air when the excess is transported to Monterey Bay for carbon sequestration efforts.

    1) https://twitter.com/nworbmot/status/1213162880230723585

    …”that 100% renewable energy requires an “overbuild” of capacity of 8x peak demand is wrong.

    The figure 8x is from a hypothetical example in a paper I co-authored.

    The real one is closer to 3-3.5x.

    Let me explain.”….

  9. Why not just use that money to UPGRADE their transmission line system? I’ll bet there are lawyers and judges blocking those electric companies from doing exactly that.

    • You can be 100% certain of that, 2hotel9, but as I mentioned above, that doesn’t touch the fact that you still have intermittent power. Sometimes more than you need, usually less than you need.

      You only need to upgrade those rural lines because you want to put bird whackers up on remote mountains in the wilderness. Ditch the windmills and suddenly those lines are still adequate to power the couple of tiny towns out there.

      They shut down Vermont Yankee nuclear power station, and the idea of ever adding hydroelectric capacity at the risk of displacing some invertebrate “endangered species” is unthinkable in Crazy Bernie Land. So expect to freeze to death in the dark.

      Stop the insanity!

      • Vermont Yankee was a victim of the warped power market in the US Northeast which has made 90% availability baseload power sources such as coal and nuclear untenable in the face of subsidized renewables which have priority access to the grid and which require backup generation which can quickly ramp up and down in real time, something which Vermont Yankee could not economically do.

        Gas-fired generation capable of load following the renewables can take up the power generation shortfall in the US Northeast. But only if the region’s politicians allow more gas pipeline capacity to be added, more gas-fired generation plants to be constructed, and/or greater transmission capacity from other states and regions which have excess generation capacity to sell. If the region’s politicians don’t allow these compensatory measures, then the US Northeast is SOL.

  10. The problem of changing phase from liquid to air in cold weather could be solved by using some of the “excess electricity” to heat liquid crystal storage, which would then, on demand, heat the liquid air. I anticipate a grid scale plant being up and running within two years max.

    No need for a / delimiter at the end of that, I hope.

    • A coal plant is typically 35-40% efficient. A CCGT gas plant about 60% efficient.

      The energy that doesn’t make it’s way into electricity is waste heat. When you see a power plant billowing out white liquid steam, that’s waste heat they are releasing.

      There is no shortage of waste heat available to warm the liquified gas.

      • “There is no shortage of waste heat available to warm the liquefied gas.”

        But after 2050, or earlier, there will be no coal or CCGT plants. Or has there been some misunderstanding?

        • Coal will hopefully be close to gone by 2030. Only 25% of US power in 2019 came from coal.

          CCGT will realistically be with us for another century at least.

          • “Coal will hopefully be close to gone by 2030.”

            Why? Coal power plants provide great baseline power with the ability to store, on site, months or even years of the source of the power, COAL!

            Just askin.

          • He’s a brainwashed fool, Drake. Do you know how many hundreds of years of coal that the United States owns? When CCGT ends, it’s back to coal.

      • Greg you said, “… white liquid steam …” That should be “white liquid condensed steam.”

      • Not to forget that LN2 tanks and pipes need to be vacuum insulated double-wall construction with vacuum pumps maintaining a high-grade vacuum. These systems are not low-maintenance!

  11. I’ve never heard of LAES before, but they are using the wrong medium.

    In Atlanta we don’t have large enough natural gas pipelines to provide our peak natural gas demand on extra cold winter nights.

    To address that, we have a “natural gas peaking plant” that makes and stores liquified natural gas [LNG]. It’s about 80% efficient. That is it takes about 20 mmbtu worth of power to liquefy and regassify 100 mmbtu of natural gas. That is more cost effective than building large pipelines that only get used to capacity a few times a year.

    LNG peaking plants like that are fairly common around the country.

    No effort is made to capture the energy created during the regassification process.

    If the LAES facility were to leverage the existing LNG peaking plants, it seems a lot of synergies could allow for a more optimized solution for both natural gas and electricity distribution.

    • But you don’t use LNG pressure changes to drive anything, you burn it, and release the potential energy in the fuel. Air provides none of that, it can only provide energy from warming it up. Their point is to be “carbon free”, which often also means “energy free”.

      • But why not leverage the energy released when LNG gassifies?

        It would drastically reduce capital cost to share the liquefaction unit.

        • Pressurized, cold LNG is gasified via an expansion valve and adding heat
          Then it is sent, as natural gas, via pipelines, to a user, such as a gas turbine peaking plant.
          LNG can be shipped by truck, as a liquid, to users, if no pipelines are available.
          Cold storage and gasifying is at the site.

        • If you want to turn a turbine efficiently, you need pressure, lots of it.
          They have just gone out of their way to tell that this system saves money by being low pressure.

    • It’s about 80% efficient. That is it takes about 20 mmbtu worth of power to liquefy and regassify 100 mmbtu of natural gas.

      Physics fail.

    • Do your energy accounting properly. The expansion of the regasified LNG means less energy input to maintain distribution pipeline pressure.

  12. Biggest problem, risk of a BLEVE ( sudden, explosive evaporation of liquid air) when thermal management, particularly in humid or warm conditions, doesn’t go as expected. These can be extremely energetic events.

    https://m.youtube.com/watch?v=NuPVEsQaGB0

    Add in the complexities of renewables/ power grid shortcomings & this idea is a recipe for disaster.

  13. From the article’s second block of quoted text: “Compressed-air storage usually requires a massive underground cavern, but LAES just needs some low-pressure storage tanks, so it’s more adaptable to areas that don’t have the right geology.”

    Just needs some low-pressure storage tanks . . . year, right . . . NOT if one intends to store that liquified air near its boiling point at the storage pressure for ten or more hours without ACTIVE refrigeration. To avoid excessive boil-off of cryogenic liquids without active refrigeration, very good thermal insulation of the storage tanks from the surrounding environment (above ground or below ground) will be required.

    The other alternative would be to design for the worst-case thermal energy leakage into the storage tanks (having zero or minimal thermal insulation) over the design storage time and then to subcool the liquified air to accommodate the energy input without causing boiling at the design storage pressure. NBP for liquid air is -194 C (-317 F) . . . but a major problem for this concept is that air freezes at -215 C (-355 F) so the ability to subcool liquid air at any “low” storage pressure is very limited.

    Also not mentioned is that in order to create liquid air for practical use, one first needs to remove all water vapor from it to prevent water ice from clogging the refrigeration process lines.

    Considering just the above, I seriously doubt that the overall, round-trip process of creating liquid air, storing it for ten or so hours in inexpensive low-pressure underground tanks, and then reheating it—all within the context of a large scale, intermittent high demand power plant—would have a realized yearly-average power efficiency greater than 50%, despite what is quoted.

    • LNG storage tanks aren’t cheap, but a state of the art LNG storage tank uses insulation only to keep the LNG liquid. 0.07% of the LNG boils off daily. That’s 2.1% per month. That is the class of storage tank used on LNG ocean tankers and they are insulating from the ocean water, which requires more insulation than insulating from air.

      LNG boils at -162C, so not too far from liquid air.

      If the economics of the rest of it can be made to work, the storage tanks can likely be made to work

      • LNG (mostly methane) has ~1.6X higher heat capacity and ~2.5X higher latent heat of vaporization, on a per-unit-mass basis, than does liquified air (mostly nitrogen). Therefore, for a given tank thermal design and equal amount of initial subcooling, expect significantly higher mass boil-off rates for liquified air compared to LNG.

      • Yeah, you’re right. The rest of the economics are so insane, that it’s not worth arguing about something that might be technically feasible but costly.

        If you really believe in the CO2 religion, then get serious and support nuclear power. That’s the only reliable, potentially cost-effective, and totally carbon-free energy source. It leaves wilderness areas untouched. No dead raptors or bats. No infrasound health effects. When the wind goes still in the midst of a cold snap in the dark of winter, it’s still there supplying carbon-free electricity. You don’t freeze to death in your bed (minor side benefit).

      • Greg, you are correct. About 0.1% [a bit more for older tankers of about 2005 build] does boil off, every day.
        Much or most is used as fuel for the ships’ main engines [except in the Q-Flex and Q-Max classes of ship; these have re-gasification units on board].
        This, incidentally, makes keeping loaded LNG Carriers at anchor an expensive pastime.

        Auto

    • So imagine a truck carrying liquid air in low pressure tanks, similar to LNG trucks, but has only 10 hours or so to get to it’s destination and “unload” (controlled depressurization of the air) into a turbine. Is there more or less risk to the public that live within a half mile of those roads in the event of traffic, minor accidents, or major collisions with another heavy vehicle?

      And how many such trucks per hour are needed to keep a 100 Mega Watt plant operation continuously?

    • You could just allow the boiloff to vent to the atmosphere — can’t hurt anything. That means LAS is a “use it or lose it” energy storage technology — You can’t incur the energy cost to liquify air once and then sit on it for months before using. To keep the tanks full there will be a steady power drain to re-liquify the boiloff.

      The other issue is you need waste heat to quickly turn the liquid air into high pressure gas to run a turbine. Which means you need a waste heat source that is guaranteed to be running when you need to use that stored energy. Certainly possible, but it does limit location choices. A conventional thermal power plant would be the obvious choice.

      The real questions are how large can you scale it, what’s the cost, what’s the footprint, what’s the round-trip efficiency, and what’s the continuous standby energy drain.

      The LCOE quoted in the article makes it more expensive than nuclear or pumped hydro.

    • LN2 tanks all use Dewar double-wall construction with a high-grade vacuum as insulation (basically a giant Thermos bottle). They can store LN2 for weeks, but do require high grade vacuum pumps to maintain the vacuum. Even so, you still have regular bleed off losses.

  14. Perhaps this can be used to power large fans, placed in front of the idled windmills.

    This isn’t “sounds crazy but it just might work”, it stops short at “sounds crazy”.

    How much energy will it take to keep this air liquid? “Low pressure storage” seems counter productive, it should be easier to keep liquid at higher pressure, I should think.

    To my mind, if you have a propane tank, design a turbine to operate at the pressure the tank releases, you get a few minutes of energy and an empty tank. Make the pipe larger (for more throughput), you get lower pressure, now you need more gas to get the earlier result. Keep scaling up, and nothing improves. The best way to use that propane is to burn it, and use that heat to heat water, and run your turbine.

    It also seems silly that, when you’re low on energy, you’re going to need a lot of it to heat this air to achieve enough pressure.

    Wait, I remember something l ike this, it was the oxygen machine, left behind by the martians, in Total Recall. For some reason, it made sense to the martians to freeze their entire atmosphere. I’m not going to become an investor in this.

    • 15% of the world’s annual natural gas consumption is liquified before consumption. It boils at -162C, so humanity has lots of experience storing liquids that boil at very low temperatures at large scale.

      For LNG (liquefied natural gas) the tanks aren’t pressurized. They maintain ambient pressure inside the storage tanks.

      The storage tanks are very well insulated and for the best tanks, 0.07% of the liquid boils off per day. 2.1% per month.

    • I don’t think keeping the air cold will be the major problem, I’ve seen some impressive insulation even on a small scale.

      As for putting fans in front of wind turbines, the Spanish allegedly tried something similar, using diesel generators to run enormous searchlights to produce solar energy at night. After this came out they trimmed the subsidies.

  15. Of course the idea was picked by the Scientific American which boldly declared war on equations – or even on most numbers. That did not prevent them from claiming a 60 to 75 percent efficiency, the number which comes straight from the company’s promotion materials.

  16. Has this kind of thing been tried before? Why yes. People have been working on compressed air powered cars for a long time. link

    If people have been working on something for a long time, all the low hanging fruit has been picked. So, why haven’t compressed air powered cars worked yet? What could you do differently so the idea would work for grid power?

    Compressed air has rather low energy density but that wouldn’t matter as much for a stationary application. Big air tanks are way cheaper than big batteries. So, stationary applications have an advantage. On the other hand, energy storage projects like this one have a long track record of not working. I thought this might work

    I’ve been following ammonia as an energy carrier. I google for articles written in the last month. There seems to be a steady supply of new projects. example That makes me think nobody has found a show stopper yet. On the other hand, this compressed air thing has reared its ugly head again.

  17. Why not fractionate the liquid air and use only the liquid nitrogen for generating electricity?

    Oxygen, argon and even CO2 have multiple industrial purposes and can add value as single components rather than generating electricity. Water extracted from the process could be bottled and sold as Icy Vermont H2O ENERGY drink and sold at a premium in California. The nitrogen component of the air could also be sold to industry or used for standby electricity generation…

    • “Water extracted from the process could be bottled and sold”

      Does it have electrolytes in it?

      I want the one with electrolytes. Not buying anything without electrolytes. I’m not an idiot; I know I need and I deserve the electrolytes.

    • But you would need to transport the water to Cal. in Tesla trucks to maintain your virtue signaling creds.

  18. Conventional power plants don’t have an intermittent power delivery problem but they do have a widely variable load problem. In the late hours of night and the wee hours of morning demand is low. In the unlikely and unforeseeable development of a cost effective storage system; it could be used to advantage at real power plants. Not at wort-less-than-nothing non-dispatchable, widely scattered, low output, off spec. wind and solar sites.

  19. Air storage seems complicated.
    Proposals to store electricity as mechanical potential energy – weights on towers, or concrete blocks on old RR cars on sloped railroad tracks – are nice visual things giving the impression of “doing something” and likely as effective. Rubber bands would work, also.
    {invoking Poe’s Law}

  20. The lowest figure I could come up with for something like wind was to just install more wind power, convert a very large portion of it into hydrogen, storing it in metal lined, bored tunnels, and then only using it industrially. That would be a much higher energy density and you can just retrofit older power plants to burn the hydrogen instead of natural gas or coal. Plus only using the hydrogen in an industrial setting fixes the majority of the handling dangers of letting your average person deal with it.

    This, by the way, drops the efficiency even more (40-50%) but we’re talking about the truly vast amounts of storage an industrial civilization would need and a stored medium that could also be distributed through pipelines.

    • As I said in another thread, if you are turning electricity into hydrogen, the sensible thing to do with it is to crack heavy hydrocarbons. Many sources of oil contain more heavy hydrocarbons that wanted, so crack them in to methane and the consumer gets the sort of gas they are familiar with.

      • Unfortunately, methane contains that ugly carbon atom . . . hydrogen does not.

        If you’re willing to accept carbon-containing fuels, the MOST SENSIBLE thing is to just utilize (combust) them in their current high energy-density form, albeit slight refining. Why welcome the entropy increase associated with any fuel-to-fuel conversion process if it’s really not needed?

      • Unfortunately you need a source of hydrogen to crack heavy hydrocarbons. The H-C ratio of methane is 4, whereas an asphaltene has an only about 1.2 ratio. You have to provide the other 2.8 from elsewhere.

  21. These storage systems also do not produce energy – they merely store very finite amounts f enegy. But the needs can be very un-finite. And where is the energy coming from to store in these systems? If they expect to get it from renewables, then they will need to increase their renewable capacity
    These renewable jackasses seem bound and determined to avoid the very obvious solution that is right on the horizon : molten salt small modular reactors. which are cheaper than any renewable and can even load follow (meet changing demands). They also can be small and used to supply a relatively small geographic area. They require no cooling water and areinherently saafe and very proliferation resistant. They are built in factories and asembled on site – sites which need little preparation.

    • ColMosby writes again and again
      the very obvious solution that is right on the horizon : molten salt small modular reactors.

      And I respond again and again – – show me.
      Get 5 working, 50 planned-located-financed, 500 on the drawing board.
      So far – – zip, zero, none.
      Some horizon!

  22. 60- 76% efficient is more likely 50- 60% . Then if it’s estimated cost is double then double that again. Time to go back to the drawing board.

  23. This makes no sense, why not use the electricity from the windmills to make hydrogen from water? Burn the hydrogen to make electricity as required.

    • That makes even less sense, in addition to the problems of storing the hydrogen, the electricity you get out by burning the hydrogen is a small fraction of the energy you put in to decompose the water.

  24. Interestingly both Highview’s plans to improve efficiency involve fossil fuels.

    To make liquefying air more efficient they plan to use waste cold from LNG regasification.

    To make regasifying the air more efficient they plan to use waste heat from fossil fuel power plants.

    The latter sort of makes sense as the fossil fuel power plants will be working hard when the power from the liquid air is needed.

    The former is less sensible as there is likely to be an inverse relationship between demand for gas and the need to store electricity.

    • The problem for them us that the South Hook and Dragon LNG terminals are on the North shore of Milford Haven, while Pembroke CCGT power station is on the South shore, next to the remaining local refinery owned by Valero.

    • Leo,
      May I help you?

      Renewable energy is like socialism.
      If it doesn’t work, its because you haven’t spent enough of other people’s money on it yet.

      Now – that looks better – no?

      Auto

  25. Just a few observations:

    This is all perfectly doable, it’s the cost that is the concern.

    Variations on the Linde process has been used for a century to liquify air. All proven and off the shelf.

    The choice of low-pressure tanks is a cost consideration at this scale.

    First, the critical point for air (temperature and pressure limit of having any liquid) is -140C and 549 psig! To store liquid air without boil-off would require both a pressure vessel with a 600 psig rating (providing 10% margin) and you’ll still have to refrigerate to prevent boil-off.

    Sure, one could use pressure vessels and minimize the boil-off from fugitive heat through the insulation, but we’re talking multi-million gallon volumes here for a grid-scale facility. That would be colossally expensive. A million-gallon Horton Sphere would be ~260 feet in diameter. It is highly likely that it is more cost effective to use atmospheric tanks, slather them in insulation and capture/recompress the boil-off.

    Looking at the Baker Hughes information, it seems that this technology is aimed at peaker plants (where one is competing with gas turbine gen sets that can be lit-off quickly unlike CCGT units) or load-leveling at a steel mill where there is already the liquid air plant (oxygen for steel making) and waste heat so the revaporization heat exchangers wouldn’t cover acres.

    If one takes the production cost of renewable MWh’s, add the cost (and losses) for wheeling that power to where its needed, add this storage cost and the cost of frequency control (unless the liquid air plants can provide sufficient spinning mass for inertia….), then we’re looking at some handsomely expensive power.

    We’ll all be slipping-on our Designer Davis hair-shirts. : )

  26. For my sins, I ended up as being something of an expert in safely treating and abandoning coal mine shafts in the UK.

    At least one of my bosses imagined that this was a very simple task. How difficult could it be to drop a load of crap down a deep hole?

    Well, actually not so simple, bearing in mind the potential for coal mine methane explosions. (And many, many other issues.)

    But one problem was a seemingly never-ending string of spittle-flecked loons who thought that abandoned mines and mine shafts would be just the thing for energy storage.

    I always tried to be polite with these guys, but it was a challenge when (as was often the case) they had a very scant appreciation of the basic laws of physics. Perpetual motion solutions abounded. None had even the foggiest idea of how to deal with methane, or even that there could be a problem.

    Occasionally, one would propose something that might actually work, if the problem could be categorised as (a) occasionally produce a bit of electricity and (b) waste as much money as possible whilst doing so.

    But the unmentioned elephant in the room was the fact that many of these crackpots were in receipt of substantial wads of taxpayers’ money, liberally handed over by various “innovation funds” (almost invariably our beloved government).

    This is what motivated them to get out of bed in the morning. Not saving the planet. These guys with their fancy liquid air notions will be cut from precisely the same cloth.

  27. The more I’ve thought about this, the more I think that it’s a ruse.

    1) An “entrepreneur” sells an idea to a friend in govt. The idea beed not be good, just good enough to convince a few lobbyists and politicians that it could work.
    2) The friend pulls some strings, makes some calls, and soon gets “development funding” for this revolutionary idea.
    3) Once the funding arrives, spend the money! Give some back to politicos, stash the rest!
    4) Declare bankruptcy. See Solyndra. The idea still exists, some still believe it could work, some other entrepreneur can “try again”. Wash, rinse, repeat.

  28. This is beyond stupid,almost as stupid as “flying cars” – which would result in smoking cremation ‘sites’ littering the urban and suburban landscape.

  29. Too bad fossil fuels haven’t already concentrated the diffuse energy of the sun. It would be so handy to have it ready-made, relatively easy to manage, and abundant without having to go through all these extra steps.

      • It’s very sad to witness the decline of a once great publication. It used to be available in my youth here in the UK IFIR for well under £1 a copy, in the days when that sum would have purchased a month’s supply of confectionery. I actually had a go at several of the “amateur projects” then to be found at the back of the magazine with varying degrees of success. Yes, my teenage impressions of the USA were formed mainly by SciAm and Mad Magazine. Can’t say they’ve changed a lot since!

  30. So engineers are proposing cryogenic refrigeration to liquify air for energy storage. Meanwhile, there are giant refrigerators running powerfully as needed to deliver heat high into the atmosphere where it more easily escapes to space. It’s called convective weather. Thunderstorms. So the same engineers, if only they would think more clearly about it, ought to be able to explain why heat cannot, in fact, be accumulated to dangerous effect on the surface of a planet which is flooded with natural refrigerant (water) and possesses an atmosphere so ready to initiate the heat engine when conditions require it. The entire problem statement – harmful warming due to greenhouse gas emissions and rising concentration – goes away when you watch a thunderstorm and see it as a refrigeration machine.

  31. The multinational M.U.F.P.C. (Magical Unicorn Fart Power Corporation) would surely capture liquid air in their invisible storage tanks at no additional charge, if the government mandates, won’t they? Although with M.U.F.P. do we really need liquid air? Shouldn’t we be using maximum capacity of invisible magical unicorn fart storage for the real deal, for the proven technology of magical unicorn farts?

  32. Stepping back from it all, it is simple. Fossil fuels/nuclear come with high density storage built in. Renewables don’t. The cost of energy storage is very high, whatever technology is used. A simple matter of thermodynamic law.
    Hence moving from fossil/nuclear to renewables as a prime source of energy will inevitably be very expensive.

    • It’s not merely a cost issue, it is an energy impossibility. The energy consumed to design, manufacture, install, maintain and administer renewables exceeds the energy they produce in their lifetime. The energy consumed to provide necessary energy storage/backup makes it worse.

      Without the energy provided by other sources, renewables cannot exist.

  33. I grew up in Vermont and one pride the people had back then was to maintain the environment in as pristine fashion as possible. The phone companies were frustrated because cell towers were a no=no. The companies designed replacements that looked like crosses on the rural churches, even pine trees. Then a massive influx of people from New York came, bought up the dairy farms that were just hanging in there so they could be Gentlemen Farmers, took over the whole political system, and decided that wind power was the way to go, even though there was sufficient energy being transmitted down from Canada. My college roommate, John Dynan Candon, who became an executive at Vt Yankee nuclear power plant, had convinced me of the efficacy of nuclear. Nooo, the answer was to dynamite the top off a beautiful mountain, promoted by the Governor, and install wind turbines in an essentially ecologically pristine location. He was not re-elected but got a job as spokesman for the wind energy company. Meanwhile the whole system, which had worked well, was messed up as this article suggests. All for fraudulent reasons and purposes. This whole fraud must be stopped.

  34. Would be perfect “fuel” for running a ship, instead of diesel . Covert diesel engine to run on high pressure air from liquid air .Easy to heat liquid with huge heatsink available (ocean) , cool ocean at same time (joke) .

  35. Wouldn’t it be great if we could take the electricity and convert it into an energy-dense stable solid that could be safely stored on or in the ground? The solid could then be used to transform the stored energy into heat and then electricity.

    Even better if we didn’t even have to manufacture that energy-dense solid because it was naturally occurring.

    • Exactly! Carbon stabilization has worked great naturally for gases and liquids too, and all this fuss about renewables is misdirected until depletion becomes a serious constraint.

  36. I’d be very surprised if this system was even 20% efficient due to problems with waste heat and icing.

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