『Abstract
　Energy is the lynchpin of modern society. Since the early 1970s, growing dependence on foreign energy sources, oil in particular, has constrained US independence in foreign policy, and at times, inhibited economic stability and growth. Addressing oil dependence is politically and economically complex. Proposed solutions are multifaceted with various objectives such as energy efficiency and resource substitution. One solution is the partial transition from an oil- to coal-based economy. A number of facts support this solution including vast coal reserves in the US and the relative price stability of coal. However, several roadblocks exist. These include uncertain recoverable reserves and the immaturity of “clean” coal technologies. This paper provides a first order analysis of the most efficient use of coal assuming the transition from oil to coal is desirable. Scenario analysis indicates two possible transition pathways: (1) bring the transportation sector onto the electric grid and (2) use coal-to-liquid fuels to directly power vehicles. The feasibility of each pathway is examined based on economic and environmental factors, among which are energy availability, affordability and efficiency, and environmental sustainability. Results indicate that partial transition of the transportation sector onto the electric grid offers the more viable solution for coal-based reduction of the US oil dependence.

Keywords: Clean coal; Oil dependence; Energy security』

1. Introduction
2. Dimensions of energy security
3. Coal as an option
4. Analysis
　4.1. Coal-to-liquids analysis
　　4.1.1. Affect on affordability
　　4.1.2. Affect of efficiency
　　4.1.3. Affect on sustainability
　4.2. Transportation to electricity analysis
　　4.2.1. Affect on affordability
　　4.2.2. Affect on efficiency
　　4.2.3. Affect on sustainability
5. Conclusion
References