Wabtec’s FLXdrive battery-electric locomotive engines might be the beginning of an answer on how railroads can reduce their carbon footprint.

Locomotive manufacturer Wabtec Corp. is helping to carve one path to a greener future for rail-carried freight. Unveiled about two years ago, Wabtec’s FLXdrive battery-electric locomotive engine is very slowly picking up steam, as freight trains and heavy haul carriers alike grapple with ways to reduce their carbon footprint, having been dependent — especially in the Americas — on diesel power and fossil fuel.

Vale, the Brazilian resources behemoth, is the latest operator to order FLXdrive engines. In July, it announced a deal to purchase three battery locomotives to carry iron ore along a specific, 140-kilometer route. Wabtec will manufacture the engines at its plant in the Brazilian state of Mines Gerais, with delivery expected in 2026.

In an interview with American Journal of Transportation, Rogerio Mendonca, Wabtec’s president, freight equipment, called the battery-electric engine “probably the biggest technology change since AC current was introduced to the locomotives in the 80s.”

In addition to Wabtec, Caterpillar’s Progressive Rail also makes a battery-electric locomotive.

Both are designed to be used primarily in tandem with diesel locomotives. That means they can cut consumption of fossil fuel and lower greenhouse gasses for freight trains, but not remove them completely.

This is hybrid technology, more Prius than Tesla. In its current iteration, one FLXdrive locomotive typically replaces a diesel engine in a three diesel-engine configuration for long haul.

Battery-powered trains can be used for switching and yards. According to Mendonca, his company envisions some all-battery-powered trains can be used in what he called “closed loop operations,” specifically mining companies that move ore from point A to point B. Mendonca cited deals to provide FLXdrive engines to Australian mining giants Rio Tinto and BHP as “very good candidates for full battery-operated trains.”

Even in its hybrid configuration, these battery-powered engines represent a significant step in tackling rail’s almost complete dependence on diesel when it comes to moving freight. Tests in 2021 registered an 11% reduction in greenhouse gas emissions, although the company has said in presentations that there can be up to a 30% reduction.

Wabtec produces battery electric engines that now range in capacity from yard-shunting locomotives, which run about 2.5 megawatt-hours, to long-haul, which are 7 to 8 mWh.

By itself, even when fully charged, this battery-power translates to a highly limited range. By comparison, a diesel locomotive carries a 5,000 gallon tank that equates to 200mWh.

Instead, the hybrid engine is designed to be recharged on the run, through an ingenious use of the heat and kinetic energy generated from braking on the downhill. “We reuse that energy,” said Mendonca. Depending on the terrain, “you can maximize the use of these batteries through recharging the kinetic energy. So basically, it’s almost as if you’re charging as you go.”

This means optimum efficiencies come from a downhill run. That means, of course, that there’s a corresponding uphill stretch as well, in which the battery electric engine isn’t producing power.

Weight is an issue as well. “Because we try to maximize the amount of batteries in the locomotive, we’re limited not only by space, but also the weight per axle that these locomotives can accommodate,” Mendonca explained. But he added that Wabtec’s current 8mWh battery locomotive weighs the same as a similar-sized diesel engine.

Software advances help as well. Software optimizes everything from how energy is used to when the battery is charged.

These are still very early days, considering the first substantial tests came only two years ago. Questions remain on everything from battery safety to charging regiments and many of those in the industry maintain a wait-and-see attitude. “Everyone is really excited about this technology,” said an official at the Association of American Railroads (AAR). “Billions of dollars being invested in exploring it. But it’s, it’s not ready for prime time yet.”

Peering into the future, what does Mendonca envision? “The battery will remain the core of the new technologies, even if it’s added to some other things that we’re exploring in early days, like hydrogen, fuel cells and other sources of fuel.”

While battery-powered locomotives hold promise for a greener future, they’re likely to be a small fraction of manufacturing output for some time to come. While Wabtec doesn’t provide data on how big its market share is, one investor presentation showed the company builds about 300 new diesel locomotives annually in the North American market.

Wabtec is short for Westinghouse Air Brake Technologies Corp. In 2019, Wabtec merged with a spinoff of GE called GE Transportation. It was GE that actually spearheaded the development of the battery engine more than a decade ago.