I agree carbon capture and sequestration is important but I haven't seen anything that looks good at scale yet.
And there won't be unless we motivate research into it.
When there is a decent solution it would be ideal at times of surplus generation when power is otherwise unable to be used
Indeed! This is an ideal use for overprovisioned capacity.
At the small scale I have an issue where in summer my solar surplus is more that my rural grid connection can handle so when my hot water is heated and the house and car are charged I end up with the solar inverters derating
Wow. I generate way more than I use in the summer, but my (also rural) grid connection can absolutely take it just fine. I have 200A service with a 150A breaker (so, about 37 kW), but my generation peaks at about 20 kW. My bigger problem is that if I try to charge my house batteries (20 kW) and my car (12kW) and run my AC (4 kW) and the steam generator (9 kW) and run basic house loads (2 kW) and run my welder (10 kW) that's 57 kW or about 235A. In practice I don't ever do all of those things at the same time (and rarely charge batteries from the grid), so I've never actually tripped the main breaker, but I could do it easily if I tried. I imagine it will happen someday.
I could swap the breaker, but the wiring from the main panel isn't big enough to have the proper safety margin at 200A. Running new wiring would be... a big project, likely involving tearing up and replacing a big chunk of my driveway. So, 150A will have to do.
I have not found a good use for such surplus power yet, but carbon capture would be ideal.
Me neither. I ran the math on doing some BTC mining (I think BTC is a scourge on the planet, but I'm happy to take money) but it didn't pencil out. Free power is great for mining, but the cost of the rigs is high enough that you really need to keep them humming 24x7, and I don't have enough battery capacity for that.