> the Carnot efficiency on that kind of temperature difference is way above 90%.
This is definitely not my area, but is Carnot efficiency directly comparable to the efficiency numbers cited in the article? Or is the "work" in Carnot efficiency the mechanical work, prior to being converted to electricity?
Yes, it's directly comparable. You can interconvert mechanical work and electricity freely; electricity isn't like heat. Everyday machinery does it with 95% efficiency, but there's no fundamental limit.
This is definitely not my area, but is Carnot efficiency directly comparable to the efficiency numbers cited in the article? Or is the "work" in Carnot efficiency the mechanical work, prior to being converted to electricity?