Compressed Air Is Great for Powering Workshops. Can It Help Power the World?

By Sophie Bushwick | July 3, 2012 12:49 pm

power grid

Despite increasing worry about what our energy consumption is doing to the planet, we’re also increasingly tied to power-hungry electronic devices. To keep reliable, renewable energy flowing, some suggest, we must give the power grid a makeover. And one method that could change it is a breath of fresh air. Danielle Fong and her company, LightSail Energy, want to store renewable energy in tanks of compressed air. Because wind and solar can be unpredictable energy sources, the ability to save any surplus for a windless or cloudy day makes them more reliable.

Caleb Garling has written about Fong’s unusual method of storing power for Wired’s World’s Most Wired feature.

In a way, Fong is going back to the future. Compressed air tanks have been used to store energy as far back as the late 19th century. They were installed in cities across the globe, from Paris to Birmingham, England to Buenos Aires. Germany has been using the technology for the past 30 years, and a power company in Alabama opened a facility in 1991. The idea is a simple one: If you have a power source — whether it’s gas or coal or renewable sources such as wind — you can use the energy to cram air into a tank. When the air compresses, it heats up, as we all know from high school physics — or just from pumping up a bicycle tire. Then, when you need the energy at some point down the road, this stored heat can be turned back into power. It’s a bit like coiling and releasing a spring. The rub is that you lose power with each transfer, and you lose heat when the air is in storage. Because it’s less than efficient, compressed air storage never caught on in a big way. Current systems often lose more than 50 percent of the power originally put into them, since they use the released energy to run a generator — which only loses more power.

But Fong has innovated the basic idea of compressed air by adding a mist to the tanks. The liquid absorbs the tanks’ heat and stores that thermal energy in water rather than air, doubling the efficiency of this energy storage method. Now, she hopes to incorporate it into the energy grid. To read more about the obstacles to compressed air’s adoption, and why Fong and LightSail are prepared to overcome them, check out the article at Wired.

Image courtesy of Tony Boon / Wikimedia Commons

CATEGORIZED UNDER: Environment, Technology
  • John W

    There are many ways to store energy – chemical batteries, water separation, hydraulic lift, flywheels, etc. The issue is the cost and the inherent losses in converting from one to the other. There is a pretty good reason we don’t see many compressed air powered cars. Compressing any gas to reasonable energy storage volumes requires heavy walled tanks and powerful compressors. Also, compressed gases require safe handling since storage tank failure is very dangerous – it is why we almost always test pressure vessels with liquids and not gases.

  • Tomek

    With all respect (and I know it was a quote), but that struck me as a sort of rubbish explanation…

    It is not as said: “When the air compresses, it heats up… Then, when you need the energy at some point down the road, this stored heat can be turned back into power”

    It is more accurate as said elsewhere, that the compressed air is like a spring, storing energy by its compression. The point about heat is key though to the article. If you lose the heat, you lose some of the energy, so you want to insulate the compressed tanks, and I guess that mist helps store some of the heat because it has high latent energy. It’s unclear though what it really does. Water is not really compressible and tends to cause problems in compressed gas systems.

    But you still have the problem that compressing the air is requiring an engine of sort, and not liable to be too efficient (i dont know the exact inefficiencies of compressing stuff). Personally I would like this more if it was windmill–>compressed gas. Because rather than having windmills–>DC generator–>Compressed Gas–>DC generator–>AC grid, this way it would cut out the first DC generator stage losses.

    I might be a bit confused, and myself at fault, but I didn’t get the most lucid understanding about what was happening from this article.

  • AlexJ

    I’ve heard of systems like this but there just seem to be too many losses to make if worth pursuing. Even if the heat from compression is saved you’re using electricity to power a moter, to power an air compressor to compress air. The air is later released to power a generator. Just in mechanical efficiency you’ve got three points of power loss not to mention the extrememly large air tanks this will require. I don’t mean to stiffle innovation, it just seems to me that the money would be better spent on battery or capacitor technology. Yes you’ll still have some loss in those technologies but not as much and with fewer moving parts maitenance is greatly reduced.

  • Tomato Addict

    There are other opportunities here. The excess heat of compression could be used to heat buildings, and on release could be used for air conditioning. Ideally you might charge the tanks at night when the power demand is low, and release it during the day for power and cooling.

  • slfnflctd

    @Tomek– Danielle Fong replied extensively to comments under her recent Wired article (which is more in-depth) and addressed the questions you are raising. The best way I can sum it up is this: you may already be aware that wind and solar power are often ‘captured’ or stored in lead-acid or lithium ion batteries– they are claiming that the method being used here is more efficient than lead-acid and is likely to last longer than lithium ion. Those are pretty big claims already, but they’re going beyond that to say that this will even be price-competitive (without subsidies) with big industry standard backup power solutions like diesel and natural gas generators. If these claims are true, there is no question that it would absolutely revolutionize the energy industry.

  • Gary B

    I’ve thought about using compressed air on my sailboat, to replace the present hydraulic anchor windlass. I would like to remove the risk of icky hydraulic fluid getting loose inside the boat, and the need to maintain fluid levels etc. – just trying to make life simpler. But folks who have used compressed air for industrial use say it’s too flaky for a boat, especially with the salt air issues. So I’m curious. I would think that if one built the system out of the right materials and with proper filtration, air might work OK.

    The most common alternative is, of course, electric but that has its own issues.

  • Iain

    Compressed air is expensive to produce, expensive to maintain and expensive to use. It won’t work economically. But I guess that won’t matter to the public when it is sold as greener than green.


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