Strongly recommended read for those interested in alternative energy:
Problem is the sum total of all energy required to produce an alternative energy.
To date, an alternative energy capable of replacing petroleum has not been found.
Petroleum supplies so much energy per barrel as to be the most efficient source known.
Alternatives to petroleum so far tested, require equal or more amounts of energy to produce, than the energy that is gained from the alternative source.
Transportation is not the only key issue:
Petroleum is currently the only known source responsible for all agricultural fertilizers, pesticides, pharmaceutical medicines, industrial manufacturing, marketing, textile production, etc... .
Even hydrogen requires more energy to produce than is gained after production.
I recommend the website above, including each and every link found on it.