Solar and Wind Power So Cheap They’re Outgrowing Subsidies

Re:Solar and Wind Power So Cheap They’re Outgrowing Subsidies by pfdietz on Sunday September 22, 2019 @07:58AM (#21040929)

I want you to be explicit in that $3000/kW figure. Is that per kW of peak OUTPUT, or per KW of effective INPUT? The input cost is spread over a longer time, so the capital cost there per kW is less important. Using nuclear for this would put all the capital cost on the output side, where it is more expensive, operating at a low capacity factor.

Consider a system intended to cover occasional shortages, happing 10% of the time. The p->g->p system would have to generate hydrogen at ~1/10th the rate it is consumed. So, if the turbines are 40% efficient, 1 kW of output capacity would require .25 kW of hydrogen generation capacity (measured in the energy content of the hydrogen; multiply by another smallish factor for efficiency of the electrolyzers).

In contrast, 1 kW of coverage from nuclear would require 1 kW of expensive nuclear capacity. You might be able to claw back some of that cost by selling power at other times, but you'll be getting only a small fraction of the total cost of making it at those times. So, the fixed costs of that nuclear capacity are going to have to be earned during that 10%, and the rate that would have to be charged would be ruinous.

I don't see how nuclear could possibly be competitive for this, if one analyzes the situation properly.

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Re:Solar and Wind Power So Cheap They’re Outgrowing Subsidies by mlyle on Sunday September 22, 2019 @12:23PM (#21042162)

> Consider a system intended to cover occasional shortages, happing 10% of the time.

Which means, in turn, that renewable has to be engineered to be sufficient for 90th percentile circumstances.

And that GTP has to have turbines sufficient for 99.99th percentile - 90th percentile circumstances. This may be a rather long tail-- in the 99.99th percentile circumstance, renewables may be making very little and demand high.

And that PTG has to have electrolyzers that have enough capacity on, say, 0-60th percentile circumstances (because you don't want to tap some things, like reservoir hydroelectric, to run PTG) to make enough gas for those outcomes.

If you have 20% of your power coming from a reliable, constant source, every step in the above chain can be much more than 20% smaller, because you absorb a lot more of the long tail and because load shedding, etc, is more effective against the remaining unreliable power.

As an aside, there's a bit of an analogy to investing. Having a bit of a low-return, reliable instrument in your portfolio is helpful. Yes, it "costs a lot" compared to investing in the market-- that 2% interest bond costs 5x as much as investing in the market to 10% average returns-- but it is a stable source of value and reduces the volatility of the cost of spending money a whole lot.

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