Hum,
nothing new...
A bit like getting `free` energy from a fridge. you are just extracting the heat from excited atoms, by pumping gas around two containers.
In this case you are just tapping into the free energy from excited atomic states...in this case its not the electron spin states; its the proton spin, that store the energy and release it , by some `trigger`...so it can really should be described as a sort of battery...
