Is the engine Andrew Porter describes in his comments on thermodynamics (
Letters, 12 February) two-stage?
The efficiency of a single-stage thermodynamic engine cannot exceed the Carnot value, which is only a function of the temperature difference — at most 50 per cent for current technologies/materials.
Anyway, we should be seeking efficient engines to burn hydrogen or otherwise use it in a fuel cell, in anticipation of wider use of this energy source. We also need safe methods of storing and retrieving the gas.
J Gray, Warks
Nanogenerator consumes CO2 to generate electricity
Nice to see my my views being backed up by no less a figure than Sabine Hossenfelder https://youtu.be/QoJzs4fA4fo