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It's funny. If storage costs drop then everything improves. Hydro would become amazingly useful cause you could run the dam all the time and store the energy in batteries. The biggest problem with power generation is the fluctuation of starting and stopping the plants. Solar would not be a sole beneficiary.

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You can store energy in a dam. Pump it up during the day, run it through the turbines at night. Probably not too efficient but lack of storage is not a convincing reason for giving up on renewables, IMO.

“Water in lakes has ~300k cubic kilometers ~ 3 * 10^14 kg http://ga.water.usgs.gov/edu/earthwherewater.html Potential energy is ~ 9.81weightheight Storage requirements (USA): 336 billion kWh = 1.2 10^18 J height = 1.2 10^18 / (9.81 * 3*10^14) kg ~ 408m

We would need to pump water in all lakes about 408m high to have 7 day worth of reserves for USA.”

http://physics.ucsd.edu/do-the-math/2011/08/nation-sized-bat...

Actually, that's wrong by three orders of magnitude. One cubic km has 10^9 cubic meters. Each cubic m has 1000 kg of water, so one cubic km has 10^12 kg. If you now have 300k cubic km, that's 3*10^17 kg.

So you actually only need to use 0.1% of all lakes.

Like the sibling comment by hyper bovine mentions, you can store energy behind a dam.

http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

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