The Intertubes lit up like a bonfire last month when the US manufacturer Wabtec introduced the first ever brand new all-electric locomotive for hauling freight in North America, so just imagine what could happen if hundreds or even thousands of battery-electric freight trains suddenly popped up on the rails. It might not happen overnight, but it could happen sooner than you think.
Battery-Electric Freight Trains
Diesel-powered freight trains have a relatively good track record on carbon emissions, so to speak. However, there is always room for improvement, especially when a climate crisis is at hand and environmental justice issues are involved. The emissions advantage of diesel freight trains will also start to evaporate when battery and fuel cell trucks start making inroads into the freight hauling market.
So far, though, battery-electric freight trains have proved to be an elusive target. Among other factors, skeptics cite logistical issues including long routes and the absence of a charging infrastructure.
Still, some activity around battery-electric freight trains has begun to stir. Wabtec’s new battery-electric locomotive, for example, will make its first runs on a 139-mile route from the suburbs of Pittsburgh, Pennsylvania to the town of Conneaut, Ohio, chaperoned by the newest iteration of the company’s fuel efficient diesel locomotives. The diesel-electric combo may disappoint electrification fans, but Wabtec still expects an overall emissions cut of 30%, which is no small potatoes.
Fuel cells offer another route to electrification. Sierra Northern Railroad in California, for example, recently won a grant to build a fuel cell electric locomotive for freight applications. It will be confined to work in a switching yard, but switcher locomotives can put in many miles a day, so the emissions savings could add up.
The Light At The End Of The Tunnel
Given this state of affairs, it may seem like the dream of battery-electric freight trains is still a dream. However, a team of researchers at the US Department of Energy’s Lawrence Berkeley National Laboratory has just published a study indicating that it could be cost-effective to convert the nation’s fleet of diesel freight trains to battery power, and it could be accomplished in just a few years.
You can get all the juicy details in the journal Nature Energy under the title, “Economic, environmental and grid-resilience benefits of converting diesel trains to battery-electric,” but the gist of it is simple. As explained by Berkeley Lab in a press release last week, the US rail freight industry is already halfway to electrification because nearly all diesel freight trains in the US already run on electric drive.
“Unlike several other regions in the world, all freight trains in the U.S. are still diesel electric, largely because the typical electrification strategy of building electrified lines over tracks is harder to implement in the U.S. with its vast distances,” Berkeley Lab explains.
“In diesel-electric trains, a diesel engine is connected to an alternator that then supplies electricity to electric motors connected to the locomotive axles. Retrofitting the trains to be powered by batteries is therefore feasible because diesel-electric trains already have an electric motor,” the lab adds.
The Case For A Rapid Switch to Battery-Electric Freight Trains
Natalie Popovich, the lead author of the study, emphasizes that speed is the name of the game. She also notes that environmental justice is a strong motivator for weaning the nation’s freight trains off diesel, along with the prospects for an overall drop in carbon emissions.
Diesel locomotive emissions account for just a small fraction of overall air pollution in the US, but the impact falls disproportionately on vulnerable communities near freight yards.
“Our analysis shows that a switch to battery-electric freight will cut the industry’s annual carbon dioxide emission by more than half, eliminating more than 400 million metric tons of carbon dioxide in 20 years,” said Popovich.
“A rapid conversion of the freight-rail sector is not only technically feasible and cost-effective, it would bring immediate and lasting health and economic benefits to lower income communities,” she added, “And it would provide a boost to our nation’s efforts to curb climate change, especially considering that U.S. freight rail capacity is expected to double by 2050.”
The key factor leveraging the authors’ conclusion is the steep, ongoing drop in the cost of lithium-ion batteries,.
“At near-future battery prices, battery-electric trains can achieve parity with diesel-electric trains if environmental costs are included or if rail companies can access wholesale electricity prices and achieve 40% use of fast-charging infrastructure,” they write. “Accounting for reduced criteria air pollutants and CO2 emissions, switching to battery-electric propulsion would save the US freight rail sector US$94 billion over 20 years.”
Battery cost is not the only factor. Another element is the relatively large size of locomotives. Paring down the weight and size of batteries is a critical issue for electric cars and trucks, but battery-electric freight trains could run on technology that focuses more attention on range and power.
The Many Benefits Of Battery Power
Despite the long distances involved in the US rail freight network, the study also notes that freight trains only average 150 miles a day. That is another factor opening up the potential for replacing diesel with batteries.
“A battery-powered freight train would use half the energy required by a diesel-electric train, and taking into account falling battery prices and environmental costs of diesel, battery-electric trains are on track to be more cost-competitive than diesel-electric trains,” the lab explains.
As for charging times, the study indicates that the centralized nature of rail infrastructure would help create economies of scale for investing in fast-charging stations.
The study notes other advantages, too. Batteries can be housed in modular tender cars, which could be unhitched and used for emergency power and other situation where a large, zero emission mobile power source would come in handy.
Battery tender cars could also be used to reduce emissions at container ports and on board container ships.
Amol Phadke, corresponding author on the study, notes that “conversion of the U.S. freight rail sector to battery-electric would generate about 220 gigawatt-hours of mobile storage.” That translates into bottom line benefits for freight train operators, too.
“This mobile energy storage capability would also create a potential new revenue stream for freight rail operators,” Phadke explains.
The Berkeley Lab team also note that retrofitting batteries on a diesel-electric locomotive could be accomplished without ditching the diesel part of the system, so diesel fuel would still be available in case a secondary fuel source is needed.
“This dual-fuel capability, allowing for either battery or diesel usage, is a unique advantage compared to fully electrifying the freight rail system or using hydrogen fuel cells,” the lab notes.
Next Steps For Zero Emission Locomotives
The study does not indicate any significant obstacles, but still, the devil is in the details. The next steps will involve additional study as well as demonstration projects on a scale large enough to cover the charging infrastructure.
Meanwhile, our friends over at Railway Age note that battery tender cars for battery-electric freight trains are already at hand. A standard freight car chassis would do the trick, with some modification.
Lithium-ion batteries are not the only option for battery-electric freight trains. Railway Age cites flow batteries as one emerging option, and they could offer duration and lifecycle advantages over lithium-ion technology.
If you have any thoughts about that, drop us a note in the comment thread.
Follow me on Twitter @TinaMCasey.
Photo: Battery-electric locomotive courtesy of Wabtec.
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