This one's pretty far out, but if the Earth's mantle or core is sufficiently conductive (composed of molten metal compounds: http://en.wikipedia.org/wiki/Inner_core), we might use it as a global electric transmission system. Use advanced materials and drilling equipment to plunge an electrode deep into the natural electricity superhighway.
Then you could pump electricity from a network of power plants at off-peak times across vast distances and use it where it's most needed. Downsides: Deep drilling technology would have to advance significantly, and it would be expensive. You would have to hope the energy flowed preferentially toward the target electrodes. There may be too much loss and dissipation. Additionally, what environmental impacts might there be? Effects on the Earth's magnetic field, for instance? Plus, if you can dig that deep already, you may as well just use geothermal heat to boil water and make your own energy onsite.
Another thought...what is electricity anyway? Movement of charged particles. What if the sloshing, rotating molten core is constantly generating electricity just by virtue of its motion? Ions and electrons rubbing off like static electricity in clouds? We may be able to drill a set of conductive taps as a cathode and anode and harvest the electrons to do work on the surface.
CATEGORY: Energy / Technology
IDEATION: May 20, 2008