The Oil Drum

There was a recent study in Scientific American which sought to show that it would be possible to generate all the power for the US using solar energy, and transmitting it as needed from the South-West to other areas.

Amongst other issues discovered was the proposed storage mechanism to make up for overnight capacity.

They wanted to use compressed air.

The problem is with that is when you come to use it you have to re-heat it, and they were going to use natural gas for the purpose.

The burn would have been huge, if my memory is correct much larger than current gas use.

Other storage proposals run into similar problems.

It boils down to that unless you are very lucky and have access to hydroelectric capacity, as Denmark does from Scandanavia, then effectively you have to have large amounts of FF capacity to back-up, and that a proportion of it will be spinning capacity, ie fired up but idling, and burning fuel in the process.
When it is brought into action it is then much less efficient for the first half hour or so.

You might also perhaps build vast polders in the ocean or great lakes, and pump water in them, but the costs would be added to the already large costs of windpower, and so are pretty impractical for the foreseeable future.

Recent costs for the UK's proposed 33GW nameplate off-shore wind build were given as £66bn - and you only get around 10-11GW of power per hour from that on average, so it works out at around £6.6bn GW - hugely expensive without building fancy storage, and at least twice the price of a nuclear build.

You can reduce that of course if you have somewhere to put the turbines on land with good wind resources, as is the case in many areas of the States, but it is still pricey before you start building huge amounts of storage.

T Boone Pickens is currently building the biggest wind farm in the world in Texas, 4GW nameplate for $10bn.

The problem is of course that the actual energy flow on average per hour on a generous figure of 35% average capacity is only around 1.4GW.

Let's round that up for convenience and to be very fair and call it 1.5GW.

That is $6.6bn GW - about half the cost of off-shore but still dear and around the price of a nuclear build which would not suffer from the same need for storage at high rates of penetration.

So the wind option can be useful, particularly where it tracks well with peak use, but is a very long way indeed from being able to power most of the grid at any reasonable cost.