By Roger Sedjo and Brent Sohngen
The growing reliance in the United States and many other industrial countries on foreign petroleum has generated increasing concerns. Since the 1970s, many administrations have called for energy independence, with a particular focus on petroleum. Although energy sources are many, the transport sector is driven largely by petroleum. Despite calls for reduced oil imports, the United States increasingly depends on foreign supply sources. General concerns about the security of petroleum supply are compounded by added concerns about the emissions of greenhouse gases (GHGs) from fossil energy, including petroleum. While the United States did not ratify the Kyoto Protocol, efforts are increasing to find alternatives to petroleum as the dominant transport fuel. The major impediment to alternative fuels is generally their higher costs as well as the existing infrastructure, which has been developed to facilitate a petroleum‐driven economy.