By Grace Renderman, Associate Editor
Researchers last month suggested the U.S. rail industry could serve as a backup transmission grid during peak-demand period if the industry deploys more battery-electric locomotives (BELs) on the tracks. With the proper planning and product development, it's certainly possible, officials from two BEL manufacturers told RailPrime recently.
In the study, published June 12 in academic journal Nature Energy, University of California–Berkeley researchers wrote that the nation’s rail network could support overrun portions of the grid — due to extreme weather events or other disasters taking out power sources — through the mobile containerized batteries attached to BELs. Deploying the rail-based mobile energy storage system (RMES) also could save the U.S. power industry more than $300 per kilowatt-year compared with the cost of building new transmission lines and $85 per kW-year compared to the cost of new stationary battery capacity, wrote study authors Jill Moraski, Natalie Popovich and Amol Phadke.
“We find that RMES is a feasible reliability solution for low-frequency, high-impact events and quantify its cost effectiveness relative to reliability-driven investments in transmission infrastructure and stationary capacity,” they wrote. “While no known technical barriers exclude RMES from grid participation, addressing interconnection challenges and revising regulatory frameworks is necessary for deployment at scale.”
From concept to reality
While it would take some reconfiguration and logistical planning, battery-powered trains could serve as emergency power during extreme situations within two or three years, says Mike Ramm, senior vice president of locomotive engineering for Progress Rail, which builds a number of BEL models, including the EMD® Joule series of fully electric locomotives that vary in battery capacity and are used in a variety of rail operations. The highest-powered unit of the Joule series is designed for mining applications and has a capacity up to 14.5 megawatt-hours.
“Battery-electric locomotives have very niche applications at this point in time,” Ramm says. “There [are] definitely opportunities for us to be able to leverage battery-electric locomotives in greater scale.”
What would it take for the rail industry to make a U.S. electric backup grid a reality? For starters, trains would need to be designed or modified with the grid in mind, Ramm says. Current models would require changes to existing charging stations and grid code requirements to ensure the correct level of power and frequency, he says. Plus, researchers and manufacturers are still working to increase battery capacity and lifespan.
“One of the things that we continue to work through is range and capability of the battery-electric locomotives to mimic more of what diesel capability can do today,” Ramm adds.
While some trains can transfer power back to the grid, there are systems in place to create a one-way flow between the BELs and the grid from which they receive power to charge the batteries, Ramm says. If trains were to be used in a backup grid situation, they’d have to be capable of two-way flow so they could not only receive power, but also return it to the grid or other sources in need. One-way flow is installed as part of Progress Rail’s safety protocol, he says.
“Our current units are equipped with a feature that prevents energy flow back to the grid,” Ramm says. “[But] it's something that has been done with current diesel-electric locomotives in emergency situations.”
BELs are similar to diesel-electric locomotives, which have been in use for years, says Wabtec President of Freight Equipment Rogerio Mendonca. Instead of a diesel-powered engine, the locomotive uses an AC electric motor connected to a power source — a set of batteries — on the top of the locomotive. The batteries and engine also must comply with Tier IV regulations as established by the U.S. Environmental Protection Agency.
A pilot battery-electric locomotive from Wabtec's FLXDrive line is in revenue service for BNSF Railway Co. Wabtec ‘The technology has evolved’
While the concept has been around for a while, the implementation and technological advancement has just begun, Mendonca says.
“Five or 10 years ago, [battery technology] was too heavy, not as efficient, too expensive,” he says. “These things were never really viable from an economic scale perspective. Now, the technology has evolved to make it viable in terms of product efficiency and reliability.”
Wabtec is currently developing the FLXDrive line of BELs, which provides energy capacity of up to 8 MWh, depending on the model. Plus, when trains brake, the massive amount of energy generated is now harvested to recharge the battery. Wabtec is developing BELs for clients in North America, Latin America and Australia, with a pilot locomotive in revenue service for BNSF Railway Co., Mendonca says. The pilot is part of a grant project with the California Air Resource Board and the San Joaquin Valley Air Pollution Control District.
The research on BELs and their potential capacity and application is still in the early stages, Mendonca says. But just in the last couple of years, an “intense search for the right technology” has accelerated development and testing of new models, leading BELs to become a core part of some rail companies’ sustainability and future development plans, Mendonca says.
While the U.S. rail network is still largely diesel-powered and will continue to be for at least the near term, Mendonca sees the industry moving to a mix of diesel (including renewable diesel), battery and biofuel energy sources in the not-so-distant future, with the rail fleet potentially becoming majority battery-electric at some point. Several railroads — including Canadian Pacific Kansas City, CSX and Union Pacific Railroad — also are studying the feasibility of hydrogen-powered fuel cells that could be used to convert diesel engines to cleaner power.
“If you go back to previous technologies, the adoption phase was definitely much longer than what we're seeing now,” Mendonca says. "In the last two years alone, we went from a conceptual development of the battery … [to] the first pilot of the battery-electric locomotive.”
The level of customer engagement in the conceptualization and development processes of Wabtec’s BELs has been encouraging, he adds.
“The pace [at] which this technology is being assessed and adopted is faster than what we've seen before,” Mendonca says.
