Potential of DME and Methanol for Locomotive Traction in India: Opportunities, Technology Options and Challenges

Locomotives are critical for the economic development of India. Majority of locomotives of Indian Railways (IR) are diesel-electric locomotives. While these locomotives offer significant flexibility and ease of operation, they have significant challenges as well such as imported fuel consumption. As the fossil fuel resources are dwindling at an alarming rate, there is a need to explore alternative fuels such as DME and Methanol, whose potential for this applications largely remains unrecognized in India. Dependence on imported petroleum can be significantly reduced by these alternative fuels. In this chapter, technical feasibility, opportunities, challenges and potential of DME and Methanol as locomotive fuels in India is discussed. These fuels are low-emission fuels, which have been overlooked in both energy policy and industry discussions, despite many attributes, which make them attractive. DME is especially suitable in diesel locomotives due to its excellent fuel characteristics. Motivation to use DME as a candidate fuel in locomotives in India comes from its soot-free emission due to absence of C–C bonds. It can be also be blended with mineral diesel to overcome limitations of using pure DME, which include low viscosity and density. Similarly, Methanol can be blended with diesel for use in locomotives. Methanol has a high latent heat of vaporization; higher oxygen content, is sulfur free and has higher burning speeds than conventional liquid fuels. When burned at high temperature, it can reduce smoke and oxides of nitrogen (NO_x) emissions from compression ignition (CI) engines. However, there are limitations in the development of pure Methanol CI engines. Such limitations have been highlighted in this chapter and partial replacement of diesel by DME and Methanol are proposed as a solution for locomotives. Modifications to prevent corrosion and overcoming issues such as low lubricity in fuel injection systems is also discussed in detail.