Comment by schiffern
The paper claims to generate energy "without a temperature gradient." If there's a hidden temperature gradient somewhere, then the paper is still incorrect.
Given the extremely small power levels, I expect that if it's not a hidden temperature gradient (eg between local air temperature and local radiant temperature, similar to PV) then they're actually seeing some sort of static electricity or air movement effect.
Yes, it is probably better described as a shitty battery NOT a thermoelectric.