He brushes off "utility-scale storage" but to actually power the country with wind, storage is a big problem. He mentions batteries. The cheapest battery is lead-acid. Here's an estimate of just how much lead it would take to run the country on lead-acid batteries:
http://physics.ucsd.edu/do-the-math/2011/08/nation-sized-bat...
Short answer: 50 times more lead than exists in known deposits, and $25 trillion dollars.
That's probably an overly pessimistic estimate. He assumes that we have to handle the wind stopping all over the country for a week (or, equivalently, going down to 30% for ten days). But I think it makes the point that renewables can't take over until we figure out scalable storage.
That article says claims that "an analysis of a future of renewable energy shows that a mix of wind and solar energy needs, at least, a two day storage capacity." With that assumption, two plugs of 500m radius and 1km deep could handle all of Germany, at a cost of half a euro per kWh.
On the other hand, my ex-geologist brother was fairly sceptical of this idea.
Doubt lead batteries would work on this scale. Other solutions: pump water up into some mountain reservoir (simlar to the granite plug idea), actually they already do this, they can run some hydroelectric power plants in reverse. Compress air into some airtight undeground chamber. Or even use giant gyroscopes to store energy for a short period (maybe night vs day type scenario).
Yep. The question though is, how much hydropower can you actually build? How much volume is available in abandoned mines and so on, or what would it cost to dig out new ones just for this? A lot of things sound great, until you actually work out the cost and maximum capacity.
Short answer: 50 times more lead than exists in known deposits, and $25 trillion dollars.
That's probably an overly pessimistic estimate. He assumes that we have to handle the wind stopping all over the country for a week (or, equivalently, going down to 30% for ten days). But I think it makes the point that renewables can't take over until we figure out scalable storage.
I did see one interesting idea: go someplace with lots of solid granite bedrock. Carve out a giant plug and store power by using hydraulics to raise the plug. http://www.solarserver.com/solar-magazine/solar-energy-syste...
That article says claims that "an analysis of a future of renewable energy shows that a mix of wind and solar energy needs, at least, a two day storage capacity." With that assumption, two plugs of 500m radius and 1km deep could handle all of Germany, at a cost of half a euro per kWh.
On the other hand, my ex-geologist brother was fairly sceptical of this idea.