Well to be honest, there are dozens of technologies that could replace oil if the government were to really open up and be serious. Too many lobbyists are keeping the technology from going forward. But there are several that show promise.

Bio-diesel- This is probably the front runner right now for a few reasons. The first is that it is almost already refined enough to use as fuel from its natural state as cooking oil, or plant oil. It is easily combustible when washed with ethanol and actually cleans the fuel systems of the vehicles that use it. This is, however, because it is slightly corrosive to certain types of rubber.

Next is ethanol, though I think this one is going to be relegated to being an additive.  Most gas companies add this to their fuel to get a greater volume and reduce carbon.  Ethanol is a type of alcohol usually derived from wood or corn, but the process to create ethanol creates almost as much carbon as the ethanol is supposed to offset.  Cellulosic ethanol has promise but is more difficult to refine then may be worth the trouble.

Old faithful solar, wind, wave, and thermal power don't generate enough to actually offset the cost of creating large scale applications.  They can still provide offsets though, and people can purchase them in the form of Renewable Energy Certificates.  To learn more go to this website.  REC's help offset the cost of renewable energy.  Plus, many companies can now trade carbon credits on the two carbon exchanges here and here.

 Now here is a treat.  I've been holding this in reserve, but I will put it out here.  Remember if you see ConEd doing this, you heard it here first.  I think an undervalued method of renewable energy is piezo-electrics.  This is where pressure is placed on a piezo-electric substance and the pressure causes shifts in the lattice work of the molecules, creating electricity.  The same principal can be seen in the click and spark lighters.  Place them in long strings across a road where thousands of cars pass daily, and they run over these things, they create D/C electricity.  From there it's a simple matter of running line to a capacitance bank, and then to a D/C to A/C converter and into the grid.  Viola, renewable energy from something we will do every day anyway.