By 2030, petroleum demand in the U.S. will be 28 million barrels per day, 72% of which will be used by the transportation sector. By that same year, over 70% of petroleum and petroleum-related products will be imported from oil-rich countries, some of which have highly volatile political and social situations (1). In addition to this dependency on foreign fuel, petroleum combustion from the transportation sector is and will remain one of the largest sources of greenhouse gas (GHG) emissions in the country (2). In addition, emissions also result from the upstream stages (before combustion) of petroleum fuels (3).

As a response to these concerns over our consumption of petroleum, interest in alternative fuel sources for the transportation sector has risen. Transportation fuels produced from coal (CTL) and natural gas (GTL) through the Fischer-Tropsch reaction have been suggested as alternative sources of transportation fuels. The U.S. is rich in coal and the technology to produce CTL has been proven: CTL fuels has been widely used in countries like South Africa. Natural gas is not as abundant in the U.S. as coal, but it is less carbon intensive. Construction of plants to produce GTL fuels for export is being considered in countries like Qatar and Malaysia with support from global oil companies (4).

If CTL and GTL fuels are being considered to be part of our transportation fuel mix, it is important to understand the impacts these fuels would have on our efforts to reduce GHG emissions. Our goal is to perform a life cycle inventory of GHG emissions associated with these fuels, and compare them to life cycle emissions of petroleum fuels. Even though CTL fuels, and to a lesser extent, GTL fuels could reduce our dependency on foreign sources of oil, our estimates suggest that CTL and GTL fuels would not contribute in reducing emissions associated with transportation fuels. In some scenarios analyzed, they could actually increase GHG emissions. This presentation will describe the method used to preform this life cycle comparison as well as the policy implications of our results.