This commentary is in response to the article “Point-of-Use ZE an Incomplete Picture,” by Nicholas Little, Railway Age, Nov. 20, 2024, which was in response to my Jan. 3, 2024 article, “ZE Energy Sources for Locomotives.”
Mr. Little notes that my article on ZE (zero-emission) locomotives for short lines does not provide comprehensive data. In particular, it is noted that there is no information on the safety of using such locomotives, the infrastructure necessary for their operation, their cost, and the possibility of using such locomotives as switchers. I disagree with some of these opinions.
On-Board Energy Storage Safety
I agree that when assessing the safety of modern switcher locomotives with on-board energy storage devices, one can focus on the safety of modern electric vehicles with lithium-ion batteries.
Data from the U.S. National Transportation Safety Board (NTSB) shows that, for all types of vehicles, electric vehicles experienced approximately 25 fires for every 100,000 sold. In comparison, approximately 1,530 gasoline-powered vehicles and 3,475 hybrid vehicles experienced fires for every 100,000 vehicles sold. Reports from other countries support the claim that electric vehicles are less likely to cause fires than gasoline-powered vehicles. Data from Norway, Sweden and Australia are consistent with the U.S. results, showing that the incidence of electric vehicle fires remains relatively low.
It should be noted that the safety of modern batteries is important not only for battery locomotives, but also for hybrid fuel cell locomotives, diesel locomotives using RNG or hydrogen as fuel, and three-mode locomotives use battery energy storage devices.
Battery Switcher Charging
Battery locomotives are charged at the depot using an external power source or in regenerative braking mode using the braking energy of the locomotive and the train it is hauling.
For example, Wabtec’s FLXdrive™ battery locomotive charger is liquid-cooled and uses a patented thermal management system designed to optimize output energy and battery life. The prototype locomotive was charged at BNSF Mormon Yard in Stockton, Calif., during testing. The charger, which includes energy converters and their control system, is located with the traction converter in the locomotive body. To charge the locomotive, three-phase, 480-volt AC at the charging station is used. In the charger, this voltage is rectified and fed to a pulse converter, its output going to the battery terminals.
The battery is equipped with a Battery Management System (BMS), a technology that ensures safety and reliability and increases the service life of battery elements, preventing damage to its individual elements. The BMS’s main function is monitoring battery parameters such as voltage, temperature, state of charge, power and reliability. The BMS determines the remaining capacity of the battery and the flow rate of the coolant. It interfaces with the on-board charger to monitor and control charging and helps maximize the locomotive’s range by making optimum use of the amount of energy stored in the battery. It is an important component of the locomotive’s equipment, ensuring that the batteries are not overcharged or discharged below an acceptable level, thereby avoiding damage.
The cost of the charger and BMS is included in the cost of the locomotive. The depot charging station, if there is no charger in it, becomes the point of connection of AC power. The design of the charging station in this case is simple, and its cost is low.
Battery Switcher Applications
Even though the specific energy of lithium-ion batteries is higher than the specific energy of storage batteries previously used on traction units, the dimensions and weight of the energy storage unit of a modern main line locomotive are quite large, and such a locomotive often requires one or more battery tenders to perform its work. A switcher locomotive does not need such a tender. The energy storage unit is placed in the locomotive carbody.
As the experience of the Progress Rail EMD® SD40JR Joule battery locomotives at Pacific Harbor Line and Vale (Brazil) shows, the energy of a locomotive battery equal to 2,400 kWh is sufficient for performing heavy switching work continuously for 24 hours.
The accumulated experience of Watco battery switcher locomotives shows similar results. Two battery switcher locomotives—1,500 hp (1,119 kW) and 1,200 hp (895 kW)—manufactured according to the Medha design, have been operating at Greens Port, the company’s multimodal terminal and port facility in Houston. During testing and the first period of operation, it was established that the locomotive does not emit harmful substances. Compared to previously used diesel locomotives, these units save on fuel and maintenance costs. According to preliminary estimates, they reduce corresponding annual costs per year by 60% and 30%, respectively, eliminating 3,000 gallons of diesel fuel and 400 gallons of lubricating oil, and reducing coolant by 80%. They also reduce noise levels. After charging their batteries for 10-12 hours, they can operate for continuously for 12.
An important advantage of a battery locomotive over a diesel locomotive is its higher energy efficiency, 77% compared to 36%.
Linehaul Service
Battery locomotives without a tender can be used in linehaul service. During tests of the FLXdrive™ at BNSF as part of a hybrid locomotive lashup consisting of two Tier 4 diesel locomotives and the prototype battery locomotive, an 11% savings in energy consumption was demonstrated, achieved through the beneficial use of the train’s regenerative braking energy. In braking mode, the battery locomotive’s traction motors operate as generators and charge the battery through converters
Wabtec and Australia’s Roy Hill, a major iron ore producer, began using a 7,000 kWh FLXdrive™ locomotive in 2023 in a hybrid consist with diesel locomotives in heavy-haul service. Four ES44ACi diesel locomotives were previously used to haul trains typically 1.6 miles long and weighing 33,000 tons. The battery locomotive was combined with these diesel locomotives. When a loaded train travels from the mine to the port, 214 miles, the line is mostly downgrade. Unloaded trains go upgrade in the opposite direction. Using regenerative braking, the FLXdrive™ charges its battery, and uses this stored energy on the return journey in traction mode. Roy Hill Road expects to see significant savings in fuel costs and emissions from the use of battery locomotives.
Carajas Railroad (EFC) in Brazil has purchased three FLXdrive™ locomotives for use as helpers on 330-car iron ore trains. Currently, three or four diesel locomotives pull the train. On the 87-mile grade in Maranhao State, two diesel pusher locomotives are used. They will be replaced by two FLXdrive™ units, reducing fuel consumption and harmful emissions.
Battery Locomotives in Thailand
CRRC’s Dalian plant in China produced a six-axle, 1,000 mm (narrow) gauge battery locomotive for Thailand. Following testing, Thailand’s Energy Absolute Public Company Limited (EA) built its own locomotive similar to the Chinese one, calling it the MINE. After a full battery charge, the 4,100-kWH locomotive can operate 200 km (125 miles) while pulling a 1,000-ton passenger train at a speed of 100 kph (62 mph).
If a 1,000-ton passenger train needs to travel 300 km (186 miles) or more, a battery tender must be attached to it, or the locomotive must be recharged along the route. Such charging requires 60 minutes, but a technology developed in Thailand can be used to replace a discharged battery with a fully pre-charged battery. According to Thai experts, such a replacement can be done in 10 minutes.
The MINE locomotive is undergoing tests at Bangkok Apiwat Central Station, the largest train station in Southeast Asia with 26 platforms. The station has several battery charging locations. In the future, it is planned to manufacture 50 locomotives similar to MINE.
Australian Battery Locomotives with Tenders
Australia’s largest railway company, Aurizon, is testing an 1,800-kWh lithium-ion battery tender developed in-house with project partner Alta Battery Technology. A hybrid locomotive with this tender, according to Aurizon, will have a 400-km (248-mile) operating range. A train with a FLXdrive™ locomotive equipped with 7,100-kWh tender is estimated by Aurizon to have an 850-km (525-mile) range, meaning that it can travel the entire distance previously covered by diesel locomotives without additional recharging.
Progress Rail has signed a contract with the Aurizon to convert Class 4000 diesel locomotives currently in service to battery. The Class 4000, which is based on the EMD GT42CUAC, was built in Australia in the early 2000s under license from EMD. A 6,700-kWh battery locomotive equipped with a 7,100-kWh tender an 850-km (525-mile) range. According to Aurizon, modification of the diesel locomotive should be completed in early 2025, and testing of the battery locomotive should take place in the first half of 2025. Watch the video:
Conclusions
- Electric vehicle safety statistics in the U.S. and other countries show that the incidence of electric vehicle fires is relatively low, and that electric vehicle safety is better than that of vehicles with internal combustion engines. Therefore, it follows that the incidence of fires in battery locomotives is also low. This conclusion can only be supported by the accumulated statistics of battery locomotive operation.
- Many battery switcher carbodies contain a charger, its control system and a battery management system (BMS). In such cases, the depot charging station has a simple circuit and is inexpensive.
- One important advantage of battery locomotives is that the battery can be used as a storage device for the train’s braking energy during regenerative braking. The accumulated energy can be used in traction mode. To take advantage of this, hybrid locomotive lashups combining diesel and battery locomotives are required.
- Battery tenders increase the operating range of linehaul battery locomotives, provided the locomotive’s battery is fully charged. However, in some cases, it is possible to use linehaul battery locomotives without tenders.
Alex Luvishis, Ph.D. for 18 years headed the laboratory that developed control systems for Russia’s first electric locomotives and asynchronous traction motors in the former USSR. For a further seven years, he headed the rolling stock department at the Institute of Technical Information of Railway Transport in Moscow. Dr. Luvishis is the author of more than 100 articles on electric traction drives and the book “Hybrid Rail Vehicles,” published in 2009. His interests are asynchronous traction drive systems for modern rolling stock, and hybrid drive systems for trams, suburban and regional trains and switching and main line locomotives. He has lived in the U.S. since 1999.
