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Published on October 9th, 2012 | by Nicholas Brown


Liquid Air Energy Storage System Could Compete with Batteries

October 9th, 2012 by  

According to the Institute of Mechanical Engineers, an energy storage system that cools air until it becomes liquid could compete with batteries. The liquid is then stored inside a vacuum flask to keep it in a cold, liquid state until it is needed. Air is a mixture of multiple gases, and most of the liquid is nitrogen.

This wasn’t invented by the IMechE, but the institute was pleased with it. It was invented by Peter Dearman, a garage inventor in Hertfordshire, to power vehicles.

12,000 BTU refrigeration compressor surrounded by stainless steel tubing.

The air has to be kept cold using the insulated flask because it will warm and vaporize easily at room temperature, causing the pressure inside its storage container to increase.

When energy is needed to back up a wind farm, for example, the liquid air is warmed and allowed to exit the flask as it vaporizes, and this causes it to vaporize faster than usual. It vaporizes extremely fast and the resulting pressure and flow rate is so high that it can turn an electricity generating turbine.


Potential Benefits of Liquid Air Energy Storage

  1. It can be built to last 20 years, which is more than twice as long as average battery technology. The equipment utilized, including the cryogenic refrigerator, storage tank (vacuum flask), turbine, and plumbing are all capable of lasting 20 years (easily) if built well. Manufacturers have far less control of battery lifespan, but a refrigerator can be built to last 5 years, or 30 if they wanted it to.
  2. It can be very efficient — the liquid air can be warmed using waste heat radiated from electricity generators, or even from the condenser of the same refrigerator that cooled the air (this is a tremendous amount of heat, by the way). Engineers said that it can be up to 70% efficient.
  3. When provided with enough heat, it can discharge its energy extremely fast, and this can be slowed down easily by reducing the amount of heat supplied to it without expensive power electronics.

“I get half a dozen people a week trying to persuade me they have a brilliant invention,” head of energy Tim Fox told BBC News. It seems this one might actually be such an invention.

Summary: The electricity generated by wind farms at times when it isn’t needed powers the system, which cools and stores air. Then, when electricity demand spikes at a time when wind speeds are too low, the system releases the air from the tank through a turbine that generates electricity and augments overall electricity production so that electricity demand can be met.

Cryogenic refers to a temperature below -150  °C.

Source: BBC
Photo Credit: Kompulsa

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is: Kompulsa.com.

  • Bob_Wallace

    Aquion has a sodium-ion grid storage battery that has been third party tested at >90% efficiency and >5,000 cycles. They are targeting <$200/kW and are working toward 20,000 cycles.

    5,000 cycles, one cycle per day, yields 13+ years life.
    Additionally their batteries show no self discharge or problems in high heat conditions. They are smaller and lighter than lead acid, easier/cheaper to ship. And 100% recyclable.

    Aquion should be in commercial production in 2013, they are now completing their factory.

    If what Aquion is reporting turns out to be true then the standard for grid storage is going to be set fairly high.

    It's likely that Ambri's liquid metal battery is going to provide even better performance per dollar.

    • In Texas at <$200 you get payback in less than 2 years, for a Biz on a peak billing plan, or for a wind farm giving the power away at night.

      • Bob_Wallace

        If Aquion and/or Ambri delivers the game changes big time. Cheap storage would blow up the energy industry.

        And there are other promising technologies being developed.

        Aquion is interesting because their batteries would be easily for retail side storage. Solar reaches grid parity much sooner at the retail side than at the wholesale side. We could see people installing home electricity storage units, buying cheap wind off-peak and using it to replace more expensive peak hour power.

  • “The research showed that the lithium battery has an energy efficiency of 95 per cent whereas the lead-acid batteries commonly used today only have around 80 per cent,”
    Clean Technica (http://s.tt/15FeQ) Feb 2012

    So with 50% upto 70% (if free heat is close by) needs to be a good bit cheaper than batteries. This look a lot like the March 2011 post, but with less data.
    Yet another innovative way to store renewable energy is being tested in the UK by a cryogenic company, Highview Power Storage, whose liquid air energy storage could be up to 70% efficient and cost just $1,000 per kilowatt.
    Clean Technica (http://s.tt/12tMh)
    In that post “Next, Highview plans to build a 3.5 MW, commercial-scale system by late 2012, building it up into an 8 to 10 megawatt storage plant by early 2014″And checking their web site, you see they have already build some. A quick look I didn’t see their current cost structure.

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