From: Jed Rothwell
Then there is deuterium, which is also costly.
No, it is cheap per megajoule of energy it produces,
assuming it produces about as much as plasma fusion. It is likely to get
much cheaper because the biggest cost component is energy. This reminds me of a 15 year old invention - which seemed doable at the time - as a way to convert a version of the heavy-water electrolysis reaction into electricity. Had anyone been able to move Pd-D to the hundred watt level, an associate was going to try to patent it. That never happened for two reasons. In 2011 - Robert Lynn, who apparently is somewhat of an expert on the subject gave a summation of the options of LENR conversion. In general: 1) Micro-turbines (Capstone et al) have low efficiency compressor and turbines and under 100kW probably won't work at all until the temperatures are 600°C, and then only with very low efficiency (<15%). MW scale might get up to 20%. 2) Micro steam turbines are very inefficient, (steam's high specific heat requires multi-stage due to blade speed limits) and with small sizes are far more prone to water erosion damage. They also require huge condensers (radiators) unless running total loss with water. 3) Reciprocating steam engines are at best 20% efficient, and then only for very intricate and large triple expansion engines, same large condenser problem. 4) Organic Rankine is also very inefficient, but by picking a fluid with lower heat of vaporization and greater molecular mass (lower specific heat) can get away with single stage. May be best of a bad lot, but again need large condensers. 5) Stirling cycle is incredibly expensive ($3000/kW @1kW, $500/kW @30kW) and heavy (10-20kg/kW) due to high precision + no lubrication. Low piston speeds mean big expensive generators. Also big radiators required. At the time he posted this, I had forgotten about the hybrid cycle invention. It would be nice to vet it, since it could have a fatal flaw as well - but essentially, it used the waste heat from micro steam with steam electrolysis for synergy. With LENR, since the heat is essentially free - one is less concerned with efficiency, so long as there is some gain - and so long as it scales up. The problem has been scale-up. I will post the hybrid cycle concept separately in another posting. Jones
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