There were some recent articles suggesting that there may be enough natural hydrogen seeping out of the ground to supply all of humanity’s energy needs. It seems a bit unlikely that leakage of hydrogen from fuel systems would matter much in comparison.
No, it gives off alpha particles and gamma rays. Hypothetically, you could build a device to harvest that energy (along the lines of an RTG), but the energy density and conversion efficiency would be laughable, given the 3.8 day half-life and gaseous state.
