One can make oil out of algae, soybeans, rapeseed (Canola), and synthetically from coal (800 year supply).
Alcohol out of corn, switchgrass, and sugar cane.
Natural gas can run vehicles. We have a 200 year supply already tapped. It can also be made from cow manure from feedstalls and dairy farms (1/3 of the nations supply). It can also be captured from sewage treatment plants.
Trouble is right now, all the alternatives costs about double what drilling costs and/or importing.
IF the feds would take all the taxes off the alternatives until they get well established, then we could wean ourselves off foreign oil. For instance, it costs $2.00 a gallon to produce algae oil, BEFORE the excise taxes.
Natural gas costs $1.37-$2.00 a gallon at refueling stations. However, there is no encouragement by the feds to convert vehicles, nor do the oil companies want to install the compressor stations.
Alcohol is the least efficient because it takes more farmland out of production. Algae oil can be produced by sea algae in shallow underwater areas or in greenhouses on land and is the most efficient to produce.