What form of excavating for small robots? Perhaps a system that has robotic analogs to the structures of coal mining, on the scale of rabbit & mole tunnels (primary & secondary). Some way to move sediment to vertical shafts to be lifted and put back later? The need to return the sediment is different than mining. Preventing flooding, while it’s being built, is the same.

Intuitively, metal blades or spikes are much better for catching/transferring heat if there was a way to get that heat to the fluid flow pipe – perhaps some kind of a heat exchange collar for the fluid pipe? Fluid flow is a transport cost. We really want more heat/cold radiators that exchange with the minimum practical lengths of fluid piping.

Perhaps some of these metal blades can be used in Thermoelectric generation in order to store excess heat in batteries that are continuously charging.

Many power systems use some form of battery storage to maintain power levels through varying usage & generation cycles. For long durability, outfield systems where space is not a critical constraint (e.g. underground usage), Sodium-ion batteries are a particularly good solution, providing low cost, high stability, high safety, & high durability. The durability & performance of these batteries would be further increased by a robotic maintenance system that was able to purify & renew the anode/cathode terminals of the system.

It would also be interesting to explore designs that couple “geothermal” (heat differential) with solar cells. I imagine a slightly tilted solar panel getting very hot in the sun & having a thin layer of cooling liquid in membrane that is flowing downhill & cycling back to the heat exchanger. There must be extra energy there.