For an exceptional medium of exchange you need long term stability, so you would want to ground that currency in the most stable thing you can find... I would say the human consumption of energy is your best bet.

US financial planners were pretty smart when they engineered the petro-dollar, and I believe bitcoin is on a similar path by becoming intrinsic to electric grid stability. In my view bitcoin should reach price stability when the majority of electric grids are underpinned by bitcoin. Bitcoin will become the electro-dollar.