Energy storage

May 14th, 2013 at 2:00 pm by David Farrar

Slate looks at energy storage. Why might we need storage in future:

California enacted a renewable portfolio standard in 2002 that ordered all utilities in the state to get a third of their electricity from wind, solar, or hydropower by 2020. Twenty-eight other states and the District of Columbia have similar requirements. But as states ramp up their use of renewables, they’ll run into a problem nobody at the lectern talked about: energy storage.

Wind turbines and solar panels produce energy intermittently, often when the grid doesn’t need it. Much of the energy they make has to be put somewhere until demand rises. The energy storage solution now most commonly used is pumped-storage hydropower: Facilities send water up a hill when the grid is producing excess power, store the water behind a dam, then release it through a turbine when demand rises. But the system requires a lot of water, and water tends to be scarce where sun and wind are abundant. What’s more, all the good spots with the right topography in the United States are already taken.

So what is needed:

The ideal energy storage solution would have five qualities: It would put a lot of energy in a small space; it would be inexpensive; it would lose in transfer less than a fifth of the energy put into storage and taken back out; it would last decades; and it would release the energy quickly. The optimal energy storage technology would also be safe to transport and non-toxic to dispose of, as well as made of raw materials that can be obtained without causing major environmental damage.

We have compressed air:

Compressed air works like this: Electricity drives a pump to pack air into a tank. As the molecules become more densely packed, they heat up. The heat is later converted back into electricity. The problem is that transfer is inefficient. Danielle Fong, co-founder of a Berkeley company called LightSail Energy, told Wired.com last year she’s invented a system that can get the efficiency up to 70 percent. (Randy Howard, LADWP director of power system planning and development, would like to see efficiency of between 85 and 90 percent.) Her prototype has impressed even investors skeptical of clean tech and attracted a fresh $37 million round of financing in November.

And flywheels:

Flywheels convert electricity to kinetic energy and back. Certain kinds can be up to 85 percent efficient, and they can run for decades with very little maintenance. But flywheel systems are expensive, becoming cost-effective only over a 20-to-30-year time horizon. Temporal Power, of Ontario, Canada, claims it has a technology that reduces energy losses; its first megawatt-size project is just getting off the ground.

But the real innovative solution:

Jim Kelly thinks he has the energy storage solution. In his 38 years in various R&D and engineering executive positions at Southern California Edison, Kelly built several pumped-storage hydropower facilities. Next month, on a ranch in the Tehachapi Mountains owned by one of the founders of the wind energy industry, Kelly’s company, Advanced Rail Energy Storage, will begin testing a variation on pumped hydro. Except instead of dams, channels, and water, Kelly’s new system has rail yards, train tracks, and electric locomotives hauling boxcars full of gravel.

These heavy-haul trains, borrowed from mining applications, use the same software as computerized trains at many airports. A motor hooked up to an electric third rail draws electricity from the grid to push the trains up a 7 to 8 percent slope; at the top, the energy is stored as potential energy. When the grid needs the watts back, the software allows the trains to run downhill at about 35 miles per hour, “releasing energy all the way,” Kelly explains. The locomotive’s motor becomes an electric generator, pushing the electricity back into the electrified rail and from there, to the grid. A large-scale storage facility that could handle 500 megawatts or more would take about 8 miles of track. The heavy boxcars are connected and disconnected according to how much power is being stored or sent back. The trains can store the power for an hour, a week, or a month with no loss over time—gravity doesn’t decay. And Kelly says they can achieve up to 90 percent efficiency. DWP’s Howard said that Kelly’s idea sounds “intriguing” and thinks it could work.

Human innovation is near endless. That is why doomsday predictions around peak oil and even climate change I have little time for. Both issues are real and important. But we shouldn’t rule out what future technology will bring us.

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35 Responses to “Energy storage”

  1. andyscrase (89 comments) says:

    The real solution is to invest in Thorium energy and give up on all this nonsense

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  2. berend (1,676 comments) says:

    DPF: push the trains up a 7 to 8 percent slope … achieve up to 90 percent efficiency

    More like 10%.

    Let me see: we use wind energy, efficiency less than 20%, it kills birds, it’s noisy, and we use that to push gravel uphill. Daft.

    I suggest we use that big light out there more. It always shines.

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  3. Spoon (101 comments) says:

    @berend: There’s this thing you may or may not have heard of called “night”. While you’re correct in that the big light is still shining, for somewhere over half the day at this time of year it’s not shining anywhere we can see.

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  4. cha (3,856 comments) says:

    But the real innovative solution:

    Regenerative braking, a feature of the now discontinued EF class locomotive.

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  5. berend (1,676 comments) says:

    @Spoon: not a problem for installations in space.

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  6. Kea (11,878 comments) says:

    The ideal energy storage solution would have five qualities: It would put a lot of energy in a small space; it would be inexpensive; it would lose in transfer less than a fifth of the energy put into storage and taken back out; it would last decades; and it would release the energy quickly.

    We already have a well proven energy storage solution that satisfies all those requirements. It is even organic !

    Coal & Oil. And we have heaps of it. :)

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  7. jims_whare (399 comments) says:

    I would have thought the train would have lost a lot of energy through wheel slip unless they coated the tracks with some kind of traction grip substance.

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  8. Simon Lyall (101 comments) says:

    Actually NZ is pretty good from an energy storage point of view. We have these giant dams with tonnes of water behind them that can supply over 60% of our Electricity.

    In theory if demand drops we could turn a dam off while if demand increases we can turn on a few more turbines. In practise things are a little more complicated ( regulated max/min flows for instance).

    However compared to many countries we are quiet well off.

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  9. Adolf Fiinkensein (2,834 comments) says:

    Never mind future technology. The Greens want to ignore present day technology which has rendered their peak oil theory obsolete. It’s called fracking.

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  10. MT_Tinman (3,055 comments) says:

    jims-whare, nowhere does it say the trains are pulling the wagons, the report simply states the electricity “pushes” the trains up the hill and claims 90% efficiency.

    Rail slip may not happen at all.

    DPF I agree, innovation, if allowed, will create solutions to almost any problem.

    Communists don’t want solutions, they need problems, which is why Labour and the reds are against anything that works.

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  11. Kea (11,878 comments) says:

    Simon, we have huge potential to generate electricity from clean green hydro. The problem is not the means of production, the problem is NZ’s green fantasy world where every single dam proposal is shut down by environmental extremists. All of whom are happy to use the electricity produced by dams.

    We need to cast these primitivists naked into the forrest so they can live the dream and let the rest of us get on with life.

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  12. Harriet (4,622 comments) says:

    And that’s why we bought back Transrail !

    yeah.right. :cool:

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  13. MT_Tinman (3,055 comments) says:

    A Meridian engineer told me their soon-to-be erected SI wind-farm will generate constant electricity 24/7.

    Whoops!

    Sorry, I mean; SHOCK! HORROR! Meridian are investing in wind-generation. Don’t whatever you do buy their shares and encourage them!

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  14. Kea (11,878 comments) says:

    MT_Tinman , that is great news re the windmills.

    Here is my suggestion:

    1. Greenies and windmill supporters will be supplied exclusively electricity by windmills.

    2. They will pay a commercially viable rate that allows the company to turn a profit, proportional to the size of the investment.

    3. No government subsidies are to be given.

    Then we will trully see how well windmills work and how much support they really have. It will also be a good test of the sincerity of the greenies. They can prove to us all that they are motivated by environmental concerns and not socialism and the destruction of modern capitalist industrial society. It is a win/win situation.

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  15. Ed Snack (1,801 comments) says:

    The gravity stored solid idea using railway wagons, somehow that 90% just doesn’t sound right, although I would be happy to be proved wrong. Remember you have to transmit the energy to the site (and back again, though maybe it can be real close to the generation point), then get very high efficiencies in sending the stuff up the hill, 90% sounds ambitious, then convert it back to electricity coming down again, and 90 % at that point is also ambitious. Then there’s friction, both ways, heating losses, the loss of power as the downhill part starts out slowly (and start up to go uphill), all the myriad mechanical losses.

    Hey, maybe they’re really good engineers and they get 98-99% efficiencies all the way (compounding this goes down), but somehow I doubt it.

    But there is a lot of good research going on, and I’d be pushing three ways if we’re actually serious about decarbonizing the economy:

    Current minimization which means using hydro as efficiently as possible supplemented by a small % wind (works well with Hydro if the quantities aren’t too large) and fracking to get gas to minimize coal use. Efficiency drives if it makes you feel good but practically bugger all use.

    Medium Term investment in two ways, Nuclear modular smallish scale with 2 x stations with 2-3 reactors each. Could be Thorium (but there’s still research but the fuel situation is far better) or modern design fail-safe Uranium. Put them, say, Dargaville/Kaipara North head and Hamilton (West coast side) so they’re close to the demand. Also invest in research (jointly surely must be best) for reliable and practical solar based. That will come, how practical, who knows but it’s getting better with advanced engineering around nano-structures and that wonder material, graphene.

    Longer term and with excess power from nuclear particularly, we can convert CO2 plus water into hydrocarbon style fuels, there are more efficient ways of dealing with this being developed. Or maybe with bio-engineered organisms to do the same.

    Sure we can mix it up, some geothermal, peaking thermal, but have a plan and sorry greenies everywhere, that must include nuclear power if you are actually serious about reducing carbon output without destroying civilisation as we know it. Oh, and there’s investment needed in the grid, not just for potentially bringing Manapouri into the general grid but also to make a more distributed approach possible because if we do finish up with large scale solar it will be distributed.

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  16. peterwn (3,215 comments) says:

    The old NZ Electricity Department investigated pumped storage, but it was not viable vis a vis strategically designed and placed hydro stations. An earlier comment mentioned that hydro stations do store water and hence the operating regime is very much like that of pumped storage. Existing hydro stations provide the storage ‘sink’ needed for wind power and there is sufficient such capability to last some years yet.

    Incidentally the world’s first reticulated electricity system (Edison’s Pearl Street scheme in New York) used storage batteries so the generator could be shut down in the small hours in the morning. A significant bugbear of modern life is batteries that wear out, lose their charge, are bulky, expensive etc (just ask a Great Barrier Island resident – having to start the generator to make some toast!). The traditional lead acid battery is hard to beat for many applications despite being around for over 100 years.

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  17. jonno1 (80 comments) says:

    And then there’s the novel idea of hydraulic hydro storage using a huge block of granite. I don’t think there are any prototypes yet but the theory is sound. One great advantage is that the storage is proportional to the fourth power of the radius of the piston, so an enormous amount of energy could be stored on a relatively small site.

    http://eduard-heindl.de/energy-storage/index-e.html

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  18. Kea (11,878 comments) says:

    I think we should invest in researching new was to produce energy and there are some interesting suggestions. But the fact is we can produce more than enough power with existing technology.

    The only thing we need to do is change the law so green extremists can not shut down proposals for new power generation. Energy should be cheap and abundant here in NZ.

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  19. davidp (3,559 comments) says:

    >Except instead of dams, channels, and water, Kelly’s new system has rail yards, train tracks, and electric locomotives hauling boxcars full of gravel.

    Won’t the passengers get restless waiting at the top of the slope? And won’t they complain about having to sit on the gravel? If these problems can be solved then this may solve Auckland’s transport problems.

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  20. kowtow (7,968 comments) says:

    “California enacted….” and therein lies the problem.Government thinks it knows better than markets.

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  21. Than (440 comments) says:

    All good ideas. I like the trainloads of gravel option in particular, I hadn’t heard about that one before. If we do end up having to build large scale storage these options would be vastly safer than building huge piles of toxic chemicals. However I have to agree with Ed Snack, those efficiency figures seem very high. Anything over 65-70% I would regard with some skepticism.

    I strongly doubt wind or solar can ever be cost-effective compared with traditional power sources in providing continuous, on-demand power. If storage can get to 80% efficient, that would require wind/solar to produce 25% more kW per dollar than other options just to be equal. And that’s ignoring the cost of building the storage itself.

    To overcome the disadvantage of requiring large scale energy storage wind and solar power will need to be at least 30% (and quite possibly 50% or more) cheaper on a simple kW per dollar basis than traditional alternatives. Right now they are close to parity, but they are also a fairly mature technology, having had billions of dollars of R&D over the last decade. I just don’t believe another 30% cost-effectiveness can be squeezed out of the technology.

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  22. Johnboy (15,602 comments) says:

    Instead of trains full of gravel we could build a railway to the top of the Denniston Plateau.

    Fill it full of green party folk and use the coal they dig out to help drag the next lot up to the mine! :)

    If lack of wheel slip was a worry we could use snails to lube the track! :)

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  23. nasska (10,917 comments) says:

    I’ve got a DVD documentary about the Denniston incline JB. Apparently they used a water fed piston braking system yet it wasn’t uncommon for the load to actually boil the water.

    There would have been a fair bit of energy released from the gravitational force involved.

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  24. Johnboy (15,602 comments) says:

    Quite right nasska. I’m all for utilising green sources of energy to save the planet.

    Why should the bastards sit in parliament eating beans and lentils at Bellamys and releasing greenhouse gases later when they can be more useful to the rest of us releasing the gases at the source…… on the plateau! :)

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  25. nasska (10,917 comments) says:

    In the DVD I referred to the producers mounted a camera to one of the wagons coming down the incline…..the gradient was an incredible 1.3/1 in places & to head down 500metres in less than 2 kilometres on the end of a steel cable supplied by the lowest tenderer would make bungy jumping seem tame by contrast.

    I’m fairly sure that the average pasty Green MP, enfeebled by a diet of mung beans & organic lettuce, would release incredible amounts of potential energy if given a chance to experience the ride. :)

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  26. Johnboy (15,602 comments) says:

    I’d be happy to quote a really cheap price for the cable nasska.

    I’ll give Penny a call and she what size knitting needles she has available! :)

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  27. hj (6,754 comments) says:

    Human innovation is near endless. That is why doomsday predictions around peak oil and even climate change I have little time for. Both issues are real and important. But we shouldn’t rule out what future technology will bring us.
    ………
    Given nationals policies of population growth and urban sprawl we’re gonna need something with a lot of umph! Personally good urban design, walkability, cycling and slow manageable population growth are preferable (I think).

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  28. Griff (7,016 comments) says:

    Nz is75% renewable now.
    Wind will be a part of future energy production
    Our hydro has sufficient capacity to act as a buffer
    costs are high due to rma hoops and uncertainTy.o
    fossel fuel is sunset technology .
    get over it.

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  29. hj (6,754 comments) says:

    Human innovation is near endless. That is why doomsday predictions around peak oil and even climate change [National has] little time for?
    Aaron Gilmore broke cover.

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  30. hj (6,754 comments) says:

    Don’t forget the alpine fault.

    http://www.orc.govt.nz/Information-and-Services/Natural-Hazards/Great-Alpine-Fault-Earthquake/

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  31. Kea (11,878 comments) says:

    Sorry Griffy you need to get with the times. There are plenty of fossil fuels and we are not even close to running out. We have plenty of oil and coal that we need to harvest.

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  32. Kea (11,878 comments) says:

    Is Peak Oil A Myth?
    We were supposed to be close to running out of oil right now, but we have more than ever.

    At times, the idea of “peak oil” has been almost interchangeable with climate change. Campaigners for action on global warming have often relied on a practical argument that fossil fuels are running out anyway. However, there’s increasing evidence that the second case doesn’t back the first.

    Griff, it seems even your fellow climate alarmists don’t agree with you… again !

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  33. pollywog (1,153 comments) says:

    Yep…one bright spark could make current energy production obsolete, practically overnight. If the means can be reproduced simply and cheaply by your average backyard tinkerer…

    Somewhere out there is a Tesla crossed with an Einstein with a revolutionary idea.

    And he/she is probably Asian.

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  34. RRM (9,668 comments) says:

    I’d like to see a mega-scale lead acid battery, built in some giant underground concrete vault.

    Would be great for disposing of bodies also…

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  35. Hiro Protagonist (17 comments) says:

    As others have mentioned, a country with as much hydro capacity as NZ doesn’t NEED energy storage, and certainly nothing as wasteful as pumped hydro. Solar/Wind power can be ‘stored’ by simply generating less from hydro.

    However if we did need storage, we also have the capability for that right in our backyard. Aluminium can be used as a battery: http://en.wikipedia.org/wiki/Aluminium_battery, to ‘charge’ you smelt Alumuinium Oxide to metallic alumuinium, discharging produces alumuinium oxide which can be re-smelted [i.e. you don't 'use up' the alumuinium]. It’s also stable for decades, so no self-discharge.

    Short answer: NZ doesn’t need to worry about energy storage.

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