UP Tests First-of-its-Kind Hybrid Locomotives

May 3, 2024 | by magnews24.com

By Railfan & Railroad Staff

Union Pacific has begun testing new hybrid battery-electric locomotives, the first of six sets that will be built along with its partner, rail technology company ZTR. 

The locomotive sets, which is built from a pair of SD40-2s, have the ability to run on both diesel and batteries — much like today’s plug-in hybrid cars. The remaining five hybrid locomotive sets are expected to be ready for testing next year. The locomotive are being built at UP’s shop in North Little Rock, Ark. 

“This is an incredibly exciting pilot project with great potential to improve the fuel efficiency of our locomotive fleet,” said Beth Whited, President of Union Pacific Railroad. “It underscores our strong commitment to exploring and developing alternative energy sources while reducing our carbon footprint and advancing our sustainability goals.”

Union Pacific worked closely with ZTR on the project: ZTR designed the hybrid propulsion technology, while Union Pacific built the prototype.

“We are excited about the groundbreaking hybrid technology built in partnership with Union Pacific. Union Pacific is serious about reaching their sustainability goals and they have been an outstanding partner in this project,” said Sam Hassan, CEO and President of ZTR. “The development of the ZTR BLU Technology platform is one of the most significant projects for ZTR to date and will be the basis for further advancements in sustainable solutions, including emission-free locomotives.”

The hybrid locomotives will operate as “mother-slug” units, with one locomotive running on diesel and an accessory or “slug” unit providing battery power. The batteries will have multiple charging options, including wayside charging and onboard self-charging capabilities. The engineless slug design increases the number of traction motors available, enhancing the locomotive’s pulling and braking power for yard switching. 

Depending on the mode of operation, these hybrid switchers are expected to consume as much as 80 percent less fuel – reducing associated greenhouse gas and criteria pollutants. Additional benefits include reduced maintenance expense and noise compared to traditional diesel units.


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