Rail Energy Technologies for the 21st Century: A Summary Review and Analysis

This paper evaluates the practicality, costs and greenhouse gas-related benefits of different propulsion technologies and fuels for U.S. freight and passenger rail. Two example routes, one existing and one devised, are used to construct the analysis and better understand the implications of fuel strategies in a “real world” context. Although diesel-electric locomotives currently dominate freight and non-urban passenger rail, a number of other fuels could be considered in the near future. These include biodiesel and the more recent “renewable diesel” drop-in diesel replacement fuels. With the low natural gas prices of recent years, natural gas is another important fuel alternative. Though few longer-distance rail systems in the US run on electricity, this energy carrier is widely used in Europe. Finally, hydrogen and fuel cells are now being explored for non-urban rail systems. These options and the requisite locomotive technologies are all considered. Two quantitative scenarios are laid out for each sub-mode: a passenger rail analysis based on California’s Amtrak-Capitol Corridor line, and a freight analysis based on a generalized 2000-mile corridor. Scenario findings are that costs and CO2 impacts of the technology/fuel options vary depending on these applications, particularly due to the much more energy- and fuel-intensive nature of freight rail; however all of the fuel options could in principle serve long-distance rail systems, though potentially involving some refueling system compromises. For both submodes there are several alternatives to diesel that provide CO2e reductions and some that provide cost savings, but no options that are clear winners in both respects.