> "A new heat engine is as efficient as a steam engine but needs a thermal source 1,800 degrees celsius hotter to work" But this title would not be correct. M

> "A new heat engine is as efficient as a steam engine but needs a thermal source 1,800 degrees celsius hotter to work" But this title would not be correct. Methane combusts at 1,957 °C, right in the band for this thermal cell, and is a normal heat source for steam power. The steam doesn't reach this temperature, of course, but nor does it need to.