By 2050, in accordance with the Paris Climate Agreement, zero-emission locomotives may have completely replaced conventional diesel-powered equipment on the railways of the world. Current development of zero-emission switcher locomotives, combined with practical operating experience, increases this likelihood in the foreseeable future. It will be increasingly possible to determine the optimal type or types of zero- or low- emission locomotives to replace conventional diesel units.
Today, four types of zero- or low-emission switcher locomotives are being developed. These are self-contained battery-electric, electric-battery (operating off overhead catenary or internal batteries) hydrogen fuel cell (HFC), and units with upgraded diesel engines using low-carbon renewable diesel or biodiesel. Below are brief descriptions of many such locomotives in current or planned operation on several railways of the world.
Battery-Electric
Progress Rail has developed a family of battery locomotives designated EMD® Joule. Some of them can be applied in switcher operations. The EMD® Joule is available five configurations, new or repowered (“R” nomenclature)—SD70J (6 axles, 8.0 MWh maximum battery capacity); SD70J-BB (8 axles, 14.5 MWh); SD40JR (6 axles, 4.0 MWh); GT38JB (4 axles, 4.0 MWh); GT38JC (6 axles, 4.0 MWh)—these units all feature regenerative braking for battery recharging. Customers can specify what they desire in MWh, up to the maximum rating. The modular EMD® Joule Charging Station provides stationary charging in 700- and 1,400-kW configurations.
An EMD® Joule SD40JR is now operating at the Port of Los Angeles with Pacific Harbor Line. The locomotive is six-axle (C-C) and equipped with an asynchronous traction drive. It can operate continuously for up to 24 hours without recharging, depending on the initial charge and load. The emission of harmful substances is zero. The battery is charged in regenerative braking mode and delivers energy in traction mode. A similar locomotive is being tested by Brazilian company Vale. Testing began in the fall of 2021 with a car dumper operation at the port of Tubarao. Main parameters: power, 2,240 kW (3,000 hp); starting tractive effort, 493 kN; weight, 118 tons. The battery energy storage is based on reliable lithium iron phosphate (LiFePO4) batteries. Bogies for 1,000 mm (meter) gauge were used on the Vale locomotive.
In Southern California, BNSF will be taking delivery next year of up to four SD70Js with charging stations for continuous operation. Their 8,000 kWh of storage capacity will make them “the most powerful battery-electric locomotives in North America.” BNSF’s acquisition is funded in part by CARB (California Air Resources Board) and EPA grant funding.
At 14,500 kWh, the SD70J-BB offers the largest known battery capacity in the industry. BHP Western Australia Iron Ore will be testing two beginning early next year.
In October 2018, Wabtec announced a plan develop a main line battery locomotive based on the AC Evolution Series diesel locomotives. In early January 2021, testing began on BNSF of the FLXdrive. Two three-axle bogies and four asynchronous (AC) traction motors are used, which drive the outside axles of each bogie (A1A-A1A). The carbody contains lithium-ion batteries with a total energy of 2,386 kWh, traction inverters similar to those used on diesel-electric locomotives with AC drive, and a microprocessor control system. Energy storage is based on lithium manganese oxide batteries with a high specific energy. The weight is 195 tons, power is 3,280 kW (4,400 hp), starting tractive effort is 640 kN, maximum speed is 75 mph.
The Wabtec family of battery-electric locomotives, in addition to the 2,386 kW prototype FLXdrive, includes switchers. According to Wabtec, a four-axle locomotive with a capacity of 1,800 kW and an energy of 2,700 kWh and a weight of 127 tons is under development. 150 similar locomotives with an energy of 1,500 kWh and an axle load of 23 tons will be manufactured jointly with the railways of
Kazakhstan beginning in 2024.
The FLXdrive program is progressing to the next level. The 2,400 kWh “Version 1.0” test with BNSF registered an 11% fuel savings operating in a consist with two diesel-electrics, vs. a three-unit diesel-electric. Two of the latest version, the 7,000 kWh FLXdrive 2.0, are shipping at the end of this year to Australia for a trial with BHP Western Australia Iron Ore (in the same trial as Progress Rail’s SD70J-BB).
This will be followed by the FLXdrive 2.5, which replaces the NMC (nickel-manganese-cobalt) batteries with GM’s Ultium NCMA (nickel-cobalt-manganese-aluminum) technology manufactured by Ultium Cells LLC, a joint venture of GM and LG Energy Solution.