Energy is technically a commodity. It has a practical use outside of just as a medium of trade. We need it for stuff. Lots and lots of stuff. So although energy supply will increase, energy demand will also exponentially increase. Perhaps even outpacing supply. New technologies, ever multiplying population of humanity, etc. The only kink in that idea is if someone manages to find a way to harness the theoretical Zero Point energy. Then other means of exchange will rise in popularity.