Every time I get into a debate about “alternative” energy I point out it can’t be used for baseline power because it can’t provide reliable power, and it can’t provide reliable power because you can’t store the electricity that it episodically generates.
Immediately, someone will say, “We can use hydraulic storage!”
Hydraulic storage is basically a hydroelectric dam on a small or large scale, except instead of using water brought by a watershed, the water is pumped up behind the dam with pumps powered by the generator whose energy output you want to store. For example, you would have electric pumps powered by solar panels or wind turbines, the idea being that when the wind or cloud-free days produced a surplus of power (or you built in surplus capacity) the pumps would pump water from a lower reservoir uphill into a higher storage reservoir. The electricity would be stored as the potential energy in the elevated water. When you needed the power back, you would drain the water back downhill through turbines just like a hydroelectric damn.
Now, this certainly works and it has been done on a small scale. However, it will never, ever be a real-world, large-scale solution that can make alternative power work.
Why? Well, let’s just do some back-of-the-envelope calculations.
(Note: Below when I say “conservative assumption” I mean an assumption biased in favor of alternative power.)
Let’s say we want alternative power to produce just 30% of our current baseline power needs. Let’s make a very conservative estimate that we only need to have a 25% stored reserve. (This very optimistically assumes that alternative power will otherwise be able to provide sufficient power, when it’s needed, 75% of the time.) So, 25% of 30% equals 7.5 % of the total (0.30*0.25=0.075).
By happenstance, hydroelectric power today produces 8% of the nation’s electricity. This means that if we want to use hydraulic storage to make alternative power work, we will have to recreate the 93% of the generating capacity of every currently existing hydroelectric facility in this country. That’s right, Hoover Dam, the entire TVA, all the damns in the Rock Mountains, all the rest, all duplicated.
That alone raises the question: Where the hell are we going to put these dang dams anyway? All the places with the geography and the water supply to produce hydroelectric power are already in use. Worse, all the places that produce significant amounts of solar and wind power are simultaneously the worst places to build hydroelectric facilities. Solar energy is produced most abundantly in, wait for it, the desert, and wind power is produced most abundantly in very, very flat places. So any hydroelectric storage facilities will have to be a long, long way off from the point of generation.
It gets even sillier. Hydroelectric storage is only around 25% efficient. This mean that to get 1 watt back out of the system you have to put 4 watts in. This in turn means that in order to create a 25% energy store of 30% of total power, you have to actually generate 30% of total power just to get 8% of total power back out. All that in addition to 30% of the total power that goes straight into the grid.
So, to get 30% of total power from an alternative power system you actually have to build the generating capacity to supply 60% of total power! Half of the alternative power will go into immediate consumption and half will be stored.
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1 comment:
I'd appreciate it if you didn't copy and past the entire post.
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