I think the problem is that the temperature of the heat source is too low. It's quite hard to recuperate energy from low temperature waste heat economically. With waste heat from high temperature sources, you can use steam, which can 'store' a lot of energy because of the latent enthalpy difference, which results in low mass flow rates. With water, you would need higher mass flow rates, so bigger tubes, pumps ...
I initially used FlorisBoard, but I changed to OpenBoard for the automatic corrections. As far as I know, FlorisBoard can only underline errors in red, then you have to tap the word and select which option it should be. On OpenBoard, a correction is made automatically, and it's quite accurate!
I think most of the technologies you mention are currently still too expensive, can't be used everywhere or don't make sense to be used at a large scale. E.g. for pumped hydro you need height differences. Concrete blocks on pullies sound like you need a lot of space for only a small amount of energy (I didn't do the maths, this is just my feeling, so correct me if I'm wrong).
About nuclear energy: in the article I saw that it accounts for 18% of the US electricity production. That's half of the 40% emissions-free part. So for sure we cannot reach the targets without nuclear energy. My opinion is that we should keep using it and keep investigating it further, just as we should keep investigating new electricity storage technologies.
It does not make sense to compare the price of energy storage (lithium batteries), with the price for generating electricity (nuclear energy), or do you mean something else?
*Rely 🤣. It's true, but for me it's just much faster to have auto-correction, I usually know how words should be written, but I hit the wrong letter quite often, so that's why this works for me.
The problem is that there are currently no good (cheap, scalable) technologies to store these large amounts of electrical energy.