Johnd said:
There are plenty of viable alternatives to fossil fuels RIGHT NOW! Hydrogen, solar, bio-diesel...especially the latter for the proximate future. Funding justs needs to be allocated for further r&d to make it cheaper than gasoline.
The problem isn't cheap/free energy. Hydropower and wind turbines (for example) have a moderate initial investment and a very low maintenence fee attached to unlimited energy gathering potential. This is well & good for, lets say, houses. If the world ran-out of home heating oil tomorrow there would be 'mount your own turbines' in Isle 4 of every Home Depot by next tuesday. Milton Hershey (the chocolate billionaire) ran his mansion off a single turbine/basement battery for 20 years before 'grid power' became a viable solution. If a wooden windmill can light a 49 room mansion, it can easily heat a double-wide.
The real energy crisis is gasoline. So far there are no easily portable energy sources that can completely replace petroleum (electric-hybrids, biodiesel, gasoline-ethanol blends, etc all require petroleum fuels in part). Liquid hydrogen requires gallons of petroleum to produce the equivolent fuel, and still have the same problem as compressed air for cars, to get a "useful" 400 miles on a "tank" of gas, the tank would be the size of an 18 wheeler! Can you imagine the Wal*Mart parkinglot with 1000 of those on black friday?!?!
So what we really need is: a fuel that cars/trucks/motorcycles can run on, is cheap, safe to transport, and easily installed in tens of thousands of fuel stations across the country. If you can retrofit existing vehicles to use the new fuel (like older cars have been modified to use modern unleaded gasoline) that would be super, because otherwise the nations landfills would burst with tens of millions of worthless cars.