Solar Ponds, basically long term free electricity

Has anybody heard of solar ponds? They're bodies of water that the sun warms. The warm water is transferred to working fluid like water or CO2, heating it and changing it to steam. The steam turns a steam turbine and generates electricity. Like most renewable energy, once you've built it the ongoing cost drops to next to nothing. Maintenance and miscellaneous can be figured at about $0.01/kWh. That's all the ongoing cost for electricity. As described it's basically useless because it's to inefficient. You needs acres of land, gigantic ponds, and millions to build them. But I find it very cool. I've been researching them and found several ways to make them more efficient. An old solar pond was between 5% and 15% efficiency (how much of the sun that hits it, it actually uses). I've pumped that up to 75%. Mine compare to solar like this: 1/3 of the cost, 1/5 of the land needed, 5X the efficiency. I have a background in crypto so I now how important cheap electricity can be. Oh yeah, unlike solar you don't need batteries to generate power at night or when it's cloudy. The water acts as a big battery, which is why at scale it's so much cheaper. I'd love to find a way to make a cost effective 10kW solution that made it cheap enough for residential use, but I haven't had any luck there. But at 50kW and above, they're amazing. At 5MW and 50MW, they're mind blowing. I don't have any plans to build one for myself at the moment, I'm broke. :-) But I am curious what others think, it's a technology that's been around and in use since the early 1900s, it just hasn't been practical before now.