>> Can anyone comment on the heat > electricity conversion ratio? My understanding has been that modern multi-stage steam turbines used in power plants are arou

>> Can anyone comment on the heat > electricity conversion ratio? My understanding has been that modern multi-stage steam turbines used in power plants are around 90% efficient, not 50%. They probably mean 90% of a theoretical maximum. For example, one of the results that stood out to me in thermodynamics class was that the maximum possible efficiency of an internal combustion engine (I forget which cycle) was a function of the compression ratio. In other words you could never reach 100% conversion of chemical energy to mechanical energy and the theoretical "efficiency" was a function that increased with compression ratio but could never reach 100 percent. So lets assume an engine with a given compression ratio could have a theoretical efficiency of 50 percent, but a real-world design only achieved 45 percent. Someone might say 45/50 is 0.9 or 90 percent of the theoretical limit. That's a measure of how good the design was vs what's theoretically possible, but it has little to do with the actual efficiency of the energy conversion. IIRC the best heat-to-mechanical energy conversion devices are rockets with a theoretical efficiency of 50% but it's been half my life since I studied thermodynamics, so maybe I'm off on some of this.