How to unlock unlimited geothermal energy, anywhere we want

[-rick-]

1 hour ago, sgt_woulds said:

Well, yes, if by 'better' you mean more efficient.  But they also have moving parts to wear out and require expensive and dangerous maintenance.  A TEG could be positioned off a continental shelf and just left to work for 20 years.   In an open sea environment, 'better' has a different meaning.

 

Sure. All that has to be taken into account. However, I believe that stirling engines could be made totally sealed so that the outside environment had no real bearing on their longevity. They would be costly but multiple times the efficiency and if fully sealed could be built to last a significant period of time without any maintenance. When that maintenance is needed it's a unit swap, not on-site repair.

 

I don't know enough about TEC solutions in this space but I would guess there would be a lot of expensive engineering to produce modules that could deal with the movement at sea, especially maintaining seals against seawater and interconnections in will inevitably be a large expanse of thin material that needs connecting together in quite long strings to generate sufficient voltage to be efficiently used by big scale inverters. Or lots and lots of smaller modules with separate inverters that then need connecting together in a robust way.

 

In summary, I suspect the engineering behind a stirling heat engine would be significantly lower risk, lower cost and longer life than a thermoelectric solution.

[sgt_woulds]

Possibly, if they used a liquid piston (fluidyne) stirling generator, which reduces the count down to a single moving part (the floating magnet in the linear alternator), but AFAIK these have never been made outside of the lab and efficiencies were very much lower than a 'traditional' stirling engine - probably not much better than TEG.  

 

There is a fascinating book about stirling engine experiments conducted by Phillips that I read a million years ago.  Well worth a read.  I was obsessed with Stirling engines at the time, but there are good reasons why ICE is the more dominant technology.