Reducing Energy Costs With Electric, Diesel and Dual-Powered Locomotives

Typically, the costs for traction energy add up to 20% or more of the total train operating costs with electric locomotives in Europe. Therefore, there is a high incentive for the railroads to reduce energy consumption and thus to improve operating margins. Additionally, rising costs for energy as well as environmental aspects will increase the need to reduce energy consumption in the future. Firstly, on electric locomotives the largest energy savings are obtained from power regeneration at braking. In this mode the locomotive acts as a moving power generator feeding energy back into the catenary network. Savings are typically in the range of 10 to 30%. Secondly, the driving style has a high impact on energy costs. Energy consumption can be lowered by more than 20% through an energy conscious driving style compared to aggressive driving. Thirdly, the energy efficiency of the whole traction chain is important. Electric locomotives designed for AC catenaries have an overall energy efficiency of up to 86%. Locomotives designed for 1.5 or 3 kV DC catenaries can have an overall energy efficiency of up to 90%. New technologies can potentially help to increase the power efficiencies even further. Apart from using efficient diesel engines, the fuel costs of diesel-electric locomotives can be reduced much in the same way as with electric locomotives. Regeneration of braking power on diesel-electric locomotives is, however, limited to feeding the auxiliaries and head end power (HEP) to passenger coaches. In Europe the energy costs per hauled ton-km are typically much lower with electric than with diesel traction. This gives dual-powered locomotives the advantage of overall lower energy costs for operation on both electrified and non-electrified networks. First estimates show that the total energy costs (diesel and electric operation) can be reduced by more than 35% in a mixed network with 80% electrification with a dual-powered locomotive compared to a diesel locomotive running the same train on the same route. In addition, the dual-powered locomotive provides major cost savings and increased quality of service with a one seat ride.