Another Cheap Way to Store Solar and Wind Power

May 4th, 2011 by Susan Kraemer

UK startup Isentropic Energy has proposed the simplest of thermal energy storage systems, according to Powermag. Two large containers of gas and gravel, one hot (500C) and one cold (–160C) provide the temperature difference to operate a heat pump. Off-peak surplus wind power or solar energy is used to heat up the contents of the hot tank and to retain that temperature.

No refrigerants, chemicals or water are used, and it has no particular geographic requirement, unlike several energy storage ideas currently in pilot testing. It could be cheap at utility-scale – as little as $10/kWh (one time, to build it), according to the company’s chief technology officer, Jonathan Howes, and the overall operating efficiency of the energy storage process is claimed to be 72% to 80%.

For this much energy storage, each tank of gas and gravel is the size of a small building, a little over 20 feet in height and in width, and the heat differential between the two containers (this size) operates a 6 MW heat pump. Scalability is possible. The company says that it could be scaled up: so larger containers could store more energy, and run a larger heat pump for longer.

According to Howes, it will cost about $16 million, and take up to two and a half years, to test the prototype’s ability to store and release 16 megawatt hours of power at a rate of 2 MW for 8 hours.

California is looking for energy storage now that 33% of our electricity is to come from renewable sources by 2020, ideally very fast releasing storage – in 1,000 MW units.

More energy storage is needed to even out the intermittency of renewables. To ensure a good match between the rise in renewables and storage – rather than haphazard storage development that might not be sufficient – a rising percentage of storage on the grid is mandated.

To keep the grid stable, storage that can release stored power within seconds are the most valuable to the renewable powered grid, as we see in the change in incentives now offered under new FERC director Jon Wellinghoff. It is also why General Compression’s Renewable Energy Storage that Ramps Up in Under 30 Seconds was selected by ARPA-E for funding.

FERC wants to offer higher payments to suppliers of fast storage, (FERC Wants Smaller, Faster, Distributed Storage to Speed Renewables) or at least to incentivize utilities to offer breaks to customers who conserve: Equal Pay for Negawatts and Megawatts Thanks to FERC.

Although Californian utilities do offer these “negawatts” incentives to large commercial users, some electric utilities in the South, typically coal-powered, currently actually offer these customers a break for wasting more energy. So the waste of fossil powered energy there has an impact on climate change globally, which is currently being felt in the South with extreme weather. FERC has national jurisdiction, so the rule could impact greenhouse gases nationally.

Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.

Tags: Federal Energy Regulatory Commission, General Compression, Jon Wellinghoff, Negawatt power

About the Author

Susan Kraemer writes at CleanTechnica, CSP-Today, PV-Insider , SmartGridUpdate, and GreenProphet. She has also been published at Ecoseed, NRDC OnEarth, MatterNetwork, Celsius, EnergyNow, and Scientific American. As a former serial entrepreneur in product design, Susan brings an innovator's perspective on inventing a carbon-constrained civilization: If necessity is the mother of invention, solving climate change is the mother of all necessities! As a lover of history and sci-fi, she enjoys chronicling the strange future we are creating in these interesting times. Follow Susan on Twitter @dotcommodity.

Pingback: Other Methods of Storing Solar or Wind Energy
Anonymous

Or you could just produce natural gas
- Anonymous
  
  since there are no problems with that: http://cleantechnica.com/2011/09/27/fracking-infographic/
http://www.facebook.com/james.vandamme James M. Van Damme

Lets see the 72% efficiency first before we get all excited.
- sola
  
  72% round-trip efficiency is not that bad if you can store wind energy into it which you bought at near-zero prices (or in some cases, negative prices).
  
  Also $10/kwh is an awsome capacity price. Compare this with lithium-ion, where your best price will be above $300/kwh.
- Doug Cutler
  
  Isentropic’s own site is posting a positive third party report from established firm Parsons Brinckerhoff:
  
  http://www.isentropic.co.uk/news/77/66/New-electricity-storage-technique-developed-by-Isentropic-Ltd-to-cost-less-than-30-of-Pumped-Hydro-Storage#6553964356269253
  
  from the post: “The report also estimates a round-trip
  efficiency in excess of 90%.”
  
  What I don’t quite understand whether or not this reports supports Isentropic’s claims for $35MWh or less cost. It seems the larger the scale the smaller the costs. But I’m hoping someone with actual expertise might dive into the P K report and explain in more detail for laymen.
  
  This also from the cited post: “Parsons Brinckerhoff is a leader in
  developing and operating infrastructure around the world, with 14,000
  employees dedicated to meeting the needs of clients and communities in
  the Americas, Europe, Africa, the Middle East, Asia, and
  AustraliaPacific regions.”
http://www.heatpumpreview.net/ heat pump reviews

This is really innovative and good way is explained in the post to conserve energy.Hope this technique is used to save other energy resources which in turns save energy and resources from vanish from earth.
Pingback: Company Stores Megawatts of Energy In Gravel-Filled Tanks | Energy Storage
Anumakonda Jagadeesh

Excellent way of Energy storage from Solar and Wind. The way storage of Energy from Renewables is tackled leaves much hope for these sources in the future.

Dr.A.Jagadeesh Nellore(AP),India
Anonymous

This is brilliant news. Any technological advancement that makes it easier to justify using wind and sun power as viable alternatives to conventionally generated power is to be welcomed. One day in the not too distant future the world is going to be using alternative energy sources on a major scale.
Anonymous

Not totally chemical free. Argon gas is used as the ‘air’. Argon is very abundant in the atmosphere and not particularly hazardous.

I don’t understand why they need to take build a demo project this large (think time and money). This concept should work (or not) at garbage can size and scale up.
- Filmorependrgn
  
  The requirements on the heat pump do not obviously directly scale.