e.g. volume of the worlds oceans is ~1e21 L and annual global energy production is ~3e16 Wh = ~1e20 J
1e20/(1e21*4e3) = 0.000025 ΔC
So even all world's energy production dumped into the ocean as waste heat is a minuscule direct effect. It's all in the second order effects of generating that energy...
Clever use of physics and cooling towers allows us to mitigate the problem..release the energy slowly over time or use the thermal for something else.but costs a lot more than just dumping it into ocean and doing lazy misleading napkin math.
... it is as if the only thing that suits our poor planet is some sort of very delicate homeostasis, which we disrupt, in what amounts to, our fight against entropy.-
To be clear, this isn’t an argument for underwater DCs. I just think it’s important to keep the scales of these things in view, so one doesn’t dilute actual causes of large scale climate change (GHGs etc.) with things like this that have basically zero chance of any even mesoscale effect.