CleanTechnica is the #1 cleantech-focused
website
 in the world. Subscribe today!


Clean Power riverbank

Published on September 2nd, 2009 | by Susan Kraemer

26

Pump Hydro Underground to Store Wind Power

Share on Google+Share on RedditShare on StumbleUponTweet about this on TwitterShare on LinkedInShare on FacebookPin on PinterestDigg thisShare on TumblrBuffer this pageEmail this to someone

September 2nd, 2009 by
 

Pumped hydro storage is a simple technology already in wide use. Pump water up a hill when you have available energy, let it fall when you need its power.

But Riverbank Power; a new start-up founded by a former wind developer who wants to develop large-scale energy storage, is trying out a new idea. Instead of using hills for the height, it will go the other way. Down into the ground.

Their Aquabank would let gravity drop water underground to turn turbines and make hydro electricity. That electricity would be sent from underground to the grid day time. At night, when excess wind is available; wind powered electricity would gently push the water back up to replenish its surface source.

Video after the jump:

Each project would use a source of water at ground level, an excavated cavern approximately 2,000 feet below ground and four 250-MW generators in a below-ground powerhouse.

The surface footprint would be only 5 to 10 acres, mainly for the water diversion structure and transmission infrastructure. The underground footprint would be about 100 acres.

It would use about 1 billion gallons of water for six hours of electricity production. It would take eight hours to pump out the cavern. The remaining sixteen hours each day the water supply would not be diverted.

Riverbank already has three sites permitted with FERC under review and fifteen in the works.

This is pretty amazing in itself, for such a new company, and such a novel idea, because FERC is notoriously slow and cumbersome to deal with.

Of the three permits, the first is canceled (in Ogdensburg) because of subsequent irresolvable land permitting issues. The second one in Sparta, New Jersey was for a 1000 megawatt “closed loop” system under a quarry.

Last month they found that the rock was not hard enough to support drilling, to the acute disappointment of locals eager for the jobs (and $5 million annual revenue it would bring in) and the to the relief of a neighboring community with environmental trepidation about the novel procedure.

In thanking mayors of both towns, Riverbank’s CEO Douglas said, “These leaders kept an open mind about the project, understood that scientific testing would guide the development process, and believed us when we said we wouldn’t develop a project that posed a risk to the environment.”

FERC normally grants a preliminary permit to conduct the various studies needed over three years. These cost up to $2 million, and include thorough investigation of the geologic, ecological, engineering, power transmission, economic and environmental impact.

So far, the initial studies for the third FERC permitted site are looking good and will be complete by 2011. It is for a 1,000 MW “river diversion” type of project on the Back River site in Wiscasset, Maine:

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.

Print Friendly

Share on Google+Share on RedditShare on StumbleUponTweet about this on TwitterShare on LinkedInShare on FacebookPin on PinterestDigg thisShare on TumblrBuffer this pageEmail this to someone

Tags: , , , , , , , , , , ,


About the Author

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.



  • nb

    The Grand Coulee Dam has a system somewhat like this – when electrical demand is low, it uses the power to pump water up a hill to a reservoir to avoid simply wasting electricity as the water must flow through the dam anyway. The water is simply reseased back down the hill through turbines during peak demand periods.

    For windmills, I wonder if it might simply be better to have them be pumps (rather like old farm windmills) rather than generate electricity at all. All the electricity could be generated from the water flowing downhill from a reservoir. As I understand it, electric generating windmills require complex variable pitch systems to keep them at a fairly constant speed. In extremely high winds they even have to be “feathered”. A pump will simply pump less or more water depending on the wind. Strong winds will actually help fill the reservoir faster, winds too low to power a generator might still power a water pump – just at a slower rate. The pumping windmill systems might ultimately be simpler and require less maintenance. They might be cheaper as well, although plumbing between all the windmills could perhaps make the system more costly to install.

  • nb

    The Grand Coulee Dam has a system somewhat like this – when electrical demand is low, it uses the power to pump water up a hill to a reservoir to avoid simply wasting electricity as the water must flow through the dam anyway. The water is simply reseased back down the hill through turbines during peak demand periods.

    For windmills, I wonder if it might simply be better to have them be pumps (rather like old farm windmills) rather than generate electricity at all. All the electricity could be generated from the water flowing downhill from a reservoir. As I understand it, electric generating windmills require complex variable pitch systems to keep them at a fairly constant speed. In extremely high winds they even have to be “feathered”. A pump will simply pump less or more water depending on the wind. Strong winds will actually help fill the reservoir faster, winds too low to power a generator might still power a water pump – just at a slower rate. The pumping windmill systems might ultimately be simpler and require less maintenance. They might be cheaper as well, although plumbing between all the windmills could perhaps make the system more costly to install.

  • http://www.globalenergiesinc.com Dave B

    Water Current Energy Systems could/should be used or at least considered.

    We are somewhat new in the Hydrokinetic game but will be worth watching in the coming months as we are very close to introducing our new Water Current Energy System.

    Submerged productive systems. Would prefer velocities of water over 5mph but can operate in less but of course this will also dictate size of systems.

    Could be a consideration.

  • http://www.globalenergiesinc.com Dave B

    Water Current Energy Systems could/should be used or at least considered.

    We are somewhat new in the Hydrokinetic game but will be worth watching in the coming months as we are very close to introducing our new Water Current Energy System.

    Submerged productive systems. Would prefer velocities of water over 5mph but can operate in less but of course this will also dictate size of systems.

    Could be a consideration.

  • Susan Kraemer

    The point of storage is to use wind when it is available; typically at night. Otherwise that gets wasted or sold at cheap night rates.

  • bill

    2000 feet is quite a head of water for electrical generation. Probably needs some pretty special equipment to handle that kind of pressure. The wind farm would need to generate as much energy as the hydro turbines had generated, to pump the ‘used’ water back up to the resevoir on the surface. A location with reliable wind at night would need to be selected.

  • bill

    2000 feet is quite a head of water for electrical generation. Probably needs some pretty special equipment to handle that kind of pressure. The wind farm would need to generate as much energy as the hydro turbines had generated, to pump the ‘used’ water back up to the resevoir on the surface. A location with reliable wind at night would need to be selected.

  • Susan Kraemer

    The point of storage is to use wind when it is available; typically at night. Otherwise that gets wasted or sold at cheap night rates.

  • Eric

    I live in British Columbia, Canada. About 80% of our power requirements are from Hydro Dam production. Two of three prime sites have been built since the 1950′s. The debate regarding the third undeveloped site has raged for decades. Even when you have all of the technical and geological requirements going for you, there are many who oppose further exploitation of the environment. I could see how this type of project could find favour here in B.C. What if the siting of this concept was near existing large bodies of water? Natural storage facilities. Would it matter if it were salt water?

  • Eric

    I live in British Columbia, Canada. About 80% of our power requirements are from Hydro Dam production. Two of three prime sites have been built since the 1950′s. The debate regarding the third undeveloped site has raged for decades. Even when you have all of the technical and geological requirements going for you, there are many who oppose further exploitation of the environment. I could see how this type of project could find favour here in B.C. What if the siting of this concept was near existing large bodies of water? Natural storage facilities. Would it matter if it were salt water?

  • Rodger S

    Talbingo dam ,Snowy Mountain Scheme ,Australia

  • Rodger S

    Talbingo dam ,Snowy Mountain Scheme ,Australia

  • Cyril R.

    Hills. Well yes there’s lots of them, but few have all the required characteristics: high and steep elevation, good rock qualities like impermeable layers and a robust structure to withstand the force of th upper water resevoir, etc..

    The benefit of underground is not just lower area requirements, its the great flexibility in siting. You can build this close to where the supply is: windfarms on the plains, where there is little elevation difference (hills). Or close to demand centers: big cities and industrial areas.

    These things may also help with peak water supply in wet seasons. The upper resevoir can act as a buffer. Water oversupply by rivers etc is a big problem in many parts of the world.

    I think the concept has great potential, also because of the use of conventional engineered components. No toxic chemicals used, no rare materials… this can scale up big time!

  • Cyril R.

    Hills. Well yes there’s lots of them, but few have all the required characteristics: high and steep elevation, good rock qualities like impermeable layers and a robust structure to withstand the force of th upper water resevoir, etc..

    The benefit of underground is not just lower area requirements, its the great flexibility in siting. You can build this close to where the supply is: windfarms on the plains, where there is little elevation difference (hills). Or close to demand centers: big cities and industrial areas.

    These things may also help with peak water supply in wet seasons. The upper resevoir can act as a buffer. Water oversupply by rivers etc is a big problem in many parts of the world.

    I think the concept has great potential, also because of the use of conventional engineered components. No toxic chemicals used, no rare materials… this can scale up big time!

  • Cyril R.

    2 dollars per Watt, that’s about the same installed cost as a wind turbine. 25% capacity factor, that’s a levelised cost of 6-7 cents/kWh if it lasts 50 years. Slightly lower if its 100 years, another 50 years doesn’t have that much effect on lifecycle cost. Less than a cent per kWh difference.

    Plus losses of 10-20% that makes it around 7-8 cents/kWh total. Not bad for peaking power! Should be cheaper than other options like natural gas, and much cleaner!

    Since the cost of excavation is so big, maybe it’s better, for now at least, to use abandoned mines and quarries as mentioned? Must be quite a few suitable (durable) underground mines and quarries that have been abandoned over the years… just be oppertunistic!

  • Cyril R.

    2 dollars per Watt, that’s about the same installed cost as a wind turbine. 25% capacity factor, that’s a levelised cost of 6-7 cents/kWh if it lasts 50 years. Slightly lower if its 100 years, another 50 years doesn’t have that much effect on lifecycle cost. Less than a cent per kWh difference.

    Plus losses of 10-20% that makes it around 7-8 cents/kWh total. Not bad for peaking power! Should be cheaper than other options like natural gas, and much cleaner!

    Since the cost of excavation is so big, maybe it’s better, for now at least, to use abandoned mines and quarries as mentioned? Must be quite a few suitable (durable) underground mines and quarries that have been abandoned over the years… just be oppertunistic!

  • MD

    I think Run-of-River is a better option… but that’s just me..

  • MD

    I think Run-of-River is a better option… but that’s just me..

  • John

    These systems become critical when the percentage of electricity generated by wind power goes up in the mix. The system enables us to cope with demand peaks and valleys. Also, Wind turbines sometimes have to stop producing (idling) when the grid cannot absorb the energy produced and this system lets us store that (otherwise wasted) energy, at a cost – the effective output is affected by the efficiency/losses associated with the energy storage system. Storing compressed air is another alternative, as is hydrogen production, but all of these processes have an associated efficiency which most of the time is prohibitive to their use.

  • John

    These systems become critical when the percentage of electricity generated by wind power goes up in the mix. The system enables us to cope with demand peaks and valleys. Also, Wind turbines sometimes have to stop producing (idling) when the grid cannot absorb the energy produced and this system lets us store that (otherwise wasted) energy, at a cost – the effective output is affected by the efficiency/losses associated with the energy storage system. Storing compressed air is another alternative, as is hydrogen production, but all of these processes have an associated efficiency which most of the time is prohibitive to their use.

  • Ben

    I still don’t really understand why this has to be underground… why not just have it pump from the bottom of a hill to the top of a hill. There are lots of hills in the world.

    I mean you say it frees up 100 acres, but that really isn’t that much land.

  • Ben

    I still don’t really understand why this has to be underground… why not just have it pump from the bottom of a hill to the top of a hill. There are lots of hills in the world.

    I mean you say it frees up 100 acres, but that really isn’t that much land.

    • http://twitter.com/thomascheney Thomas Cheney

      I think that there is a limited number of sites suitable for pumped hydro storage.

  • russ

    It seems this is simply reducing the effective output of the wind turbines?

  • russ

    It seems this is simply reducing the effective output of the wind turbines?

    • http://twitter.com/thomascheney Thomas Cheney

      Variability can be a problem when the penetration level of wind as a % of capacity gets too high.

Back to Top ↑