Partial Electrification Strategies for Diesel Commuter Rail's Climate Challenge

Abstract

As societal attitudes toward fossil fuels shifts, commuter railroads may be coming under increased scrutiny for their contribution to greenhouse gas (GHG) emissions. This analysis explores new possibilities created by battery-electric locomotives (BELs) in conjunction with partial electrification for en-route recharging in electrified territory. We propose a systemwide network approach that starts with one or more substations in geographically strategic locations, then electrifying just enough for sufficient electrical charge, with BELs running off the wire in non-electrified areas. As 25,000-Volt alternating-current substations generally have an 18~26-mile reach, considerable possibilities exist for new-start electrifications. This is significantly more cost-effective than a traditional approach that electrifies one corridor at a time. Although BELs are in technical development, and certain implementation challenges remains on commuter railroads, we believe BELs required to enable this type of electrification are within reach of current battery technology.

Drawing on examples in Boston, Philadelphia, Chicago, and Minneapolis, six strategies are outlined: (1) minimizing electrification costs by electrifying radial commuter networks from a centrally-located substation, (2) for systems with longer routes, using BELs to extend the central substation’s reach, (3) extending new electric service beyond existing electrifications with BELs, (4) using BELs to create new trans-regional services, (5) co-locating railroad-owned feeder lines with utility infrastructure such as electric transmission rights-of-way to maximize the geographic reach of supply substations, and (6) providing charging pads in certain limited situations. Preliminary ridership, energy sufficiency, and lifecycle cost analyses were performed to show the feasibility of BEL technology in conjunction with a substation-based, supply-side approach to designing electrification projects.