It's not clear to me that this is how supply and demand work. While increasing demand may increase investment in new capacity, it also should drive up the price of electricity. And since in some markets renewables are cheaper than carbon sources, one would expect that increasing the price per KWH will increase the production of the costlier, more polluting carbon sources.
More speculatively, due to the high volatility of cryptocurrency, I'm skeptical that major power infrastructure investments would be driven by the (presumably) extremely elastic demand of cryptocurrency mining. If I'm investing in energy infra, I'm going to invest in markets of increased consumer and industrial demand, which have fairly inelastic demand curves. Investing more to supply electricity to Bitcoin miners requires me to effectively take a bet on the future price of Bitcoin.
I think there is a solid argument that cryptocurrency mining provides high demand for excess capacity, and thus might provide a sort of credible floor for infrastructure investment returns, but that only makes sense if traditional demand are unreliable.