Pump Hydro Underground to Store Wind Power

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.

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.

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.

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.

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?

Talbingo dam ,Snowy Mountain Scheme ,Australia

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!

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!

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

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.

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.