it looks interesting (for some time I thought Climeon was working on that, but it was just a COR/organic rankine) but one problem with thermionic is that it require huge temperatures, like 700-1700C... 700C is acessible to gas+powder LENR today, but not much more...
2013/12/9 <[email protected]> > New generator creates electricity directly from heat > > "A new type of thermionic generator that turns heat or light into > electrical energy has been developed by researchers in Germany and the US. > The new design overcomes the "space-charge problem" that has plagued > previous attempts at developing practical devices. The device is about > four times more efficient than previous generators and the new technology > could find use in a range of applications including solar power and the > harvesting of waste heat. > Thermionic generators convert heat or light into an electric current by > using the temperature difference between two metallic plates that are > separated by a vacuum..." > > > http://physicsworld.com/cws/article/news/2013/dec/09/new-generator-creates-electricity-directly-from-heat > > Also see previous related post - > "[Vo]:New patent appl for LENR heat-to-electricity coversion" > https://www.mail-archive.com/[email protected]/msg87485.html > > >

