Well, thanks to @DonDegow's thread on "Generating heat by freezing water," I now present a heat energy duplication device, which you can attach to any heat energy source to essentially double the power you can generate.
The molten lead beads down the walls (at a rate of 100kg/0.4s = 250kg/s, could be doubled to get 500kg/s with a waterfall instead of bead) and becomes solid lead, transferring heat into the steam turbine chamber (which only powers on if the temp is above 585K, to keep a 15C temp difference for rapid cooling). This lead then waits its turn to fall into the cooking chamber (temp sensor set at 620K, but could probably drop). The doors open all at once, and then close one by one (every 5 sec) starting at the top and going down, trapping the lead inside the bottom door above the mesh tiles. The aquatuner to the right provides a heat source, using LESS POWER than is generated by the turbine. The batteries up top, while I typed the first couple of sentences, filled to capacity. Once the lead melts, it falls down through the mesh tiles, and then fed into an escher waterfall and back up to the top. I think a door pump would actually be a better choice than an escher waterfall (as you would need LOTS of lead for this build in survival, but could get away with way less if you used a door pump).
How does it work? Check the details in @DonDegow's post for the phase change shenanigans. I need a liquid-solid combo that changed phases above the min steam turbine temp, and hopefully had the same temp at which to change phases. Solidifying happens 3K below that temp, and the new material appears only 1.5K below that temp. You then only have to reheat the material 1.5K (saving 1.5K), which results in the doubling.
I wouldn't call this anymore an exploit than regolith melting (which is far more power positive), but you can use something like this to essentially double any heat energy you feed into the aquatuner chamber (swap it out for your favorite heat source). If you use magma, then it'll last twice as long (so you can connect this to a regolith melter). It's obviously an exploit of the rules of the ONI universe, but isn't that essentially what we do with science all the time, try to learn properties about the world around us and then exploit them for our benefit. It's called science!
@Saturnus, this seems like the kind of thing you would like to optimize. I'll give you the save file, rather than a bunch of overlays, to jump start any optimizations.
Have fun all. Happy ONI.
This reminds me of an old thread by @socooo. It's not the same thing (similar), but thought I'd share it anyway (uses old turbine, so not possible now).