What kind of energy will the world be using in 100 years?  Well it’s hard to know exactly, but according to Australian free- lance writer Chris Prunty, there are plenty of areas ripe for innovation.  One is geothermal power, which uses the natural heat of the earth that at its center, is around 6,000 degrees Celsius, and hot enough to melt rock.  Another is wave energy that could harness the power of ocean waves by channeling them through a power station chamber and past a turbine.  And a third is tidal power that could build dams across certain river estuaries, and have the tides flow through tunnels in the dam.  All have their challenges, but show there are many options for innovative exploration.