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Diesel freight trains emit 35 million metric tons of carbon dioxide annually and produce air pollution that leads to $6.5 billion in health costs, despite being only 2% of transportation sector emissions in the U.S. The deaths and adverse health impacts disproportionately affect low-income and disadvantaged communities, which are more likely to be located near freight rail yards.
The recent decline in battery prices has made it possible for freight trains to be electric. Researchers from the U.S. Department of Energy's Lawrence Berkeley National Laboratory, collaborating with UCLA and UC Berkeley researchers, argue that the U.S. can retrofit diesel-electric trains with batteries in a way that is cost-competitive with diesel. Reducing air pollution and carbon dioxide emissions would save the U.S. freight rail sector $94 billion over 20 years. Their study was published in a journal.
Natalie Popovich, a scientist at Berkeley Lab, said that a rapid conversion of the freight-rail sector would bring immediate and lasting health and economic benefits to lower income communities. It would give a boost to our nation's efforts to curb climate change, since the U.S. freight rail capacity is expected to double by the year 2050.
Heavy freight such as coal, lumber, and Ore can be moved by trains. According to the Federal Railroad Administration, rail is used to move 28% of U.S. freight around the country. Zero-emissions solutions for freight rail transport will be part of the commitment made by the US at the recent United Nations Climate Change Conference.
Diesel-electric, but not battery-electric.
The US is the only place in the world where diesel electric freight trains are still used. In diesel-electric trains, a diesel engine is connected to an alternator that supplies electricity to electric motors that are connected to the locomotive axles. Diesel-electric trains already have an electric motor, so retrofitting them to be powered by batteries is feasible.
Amol Phadke, a scientist at Berkeley Lab, said that dramatic improvements in battery technology and the existing electric drivetrain in diesel-electric freight trains pave the way for a rapid conversion to battery-electric freight rail. The weight of batteries is not as important as it would be for electric vehicles or trucks. The weight of the battery car in a freight train is not an issue for trains.
Diesel-electric trains have been around since the 1920s, and they started to replace steam trains in the 1930s since they were less polluting. Diesel engines were cheaper to use than to develop fully electric trains due to high electricity costs. The environmental and health costs of continuing to rely on diesel to power freight trains are too devastating to ignore, as we are at a point where the price of electricity is competitive with diesel.
The analysis shows that a switch to battery-electric freight will cut the industry's annual carbon dioxide emission by more than half.
The study shows that there are additional pathways to spurring the use of hydrogen fuel cells and battery-powered trains. The researchers show that the battery-electric pathway is the most cost-effective, long-term solution with multiple added benefits because freight trains are already diesel-electric.
The average daily distance traveled by a freight train is 150 miles. 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. Since freight rail planning is centralized, the study suggests that railroads could achieve high volume use of fast-charging infrastructure, which would further reduce costs.
The benefit of retrofitting existing diesel-electric freight trains with battery cars is that they can always be a backup fuel source. This dual-fuel capability, allowing for either battery or diesel usage, is a unique advantage compared to the use of hydrogen fuel cells.
The resilience benefits of modular batteries.
The electric grid's resilience is strengthened by the fact that battery-electric trains can be deployed as clean backup power. During emergencies, diesel-electric trains have been used as power generators. In 1998 there were ice storms that left over a million people without power in the US and Canada. In one suburb of Montreal, the mayor moved a diesel-electric locomotive close to City Hall to provide power for their emergency response operations.
With the rise of extreme weather events, battery-electric trains have the potential to be deployed nationwide to avoid power failures. The modular, battery tender cars can be transported to where they are needed and charged in locations where the electricity prices are low, thus offering significant advantages over grid-scale storage. The battery tender cars could be used as modular shipping containers, capable of exchange between freight rail and maritime shipping vessels, with positive benefits to decarbonizing both sectors and expanding the resilience reach.
The conversion of the U.S. freight rail sector to battery-electric would generate 220 gigawatt-hours of mobile storage. The recent catastrophic wildfires in California or the winter storm in Texas that left millions without access to electricity are examples of extreme events that battery tender cars could be used for. The mobile energy storage capability would create a new revenue stream for freight rail operators.
There should be no constraints in moving to fully battery-electric freight trains, but further research and large-scale demonstration projects are needed to improve charging infrastructure. Berkeley Lab's systems and markets analyses show that we can decarbonize some sectors with existing technology, which will help us reach our climate goals that much faster while also helping environmental justice and grid resilience. Noel Bakhtian is the director of the Berkeley Lab Energy Storage Center. The techno-economic analysis of battery-electric freight trains shows that there are viable solutions available to enable the transition to a clean, affordable, and resilient energy future.
Natalie D. Popovich and her co-workers discuss the benefits of converting diesel trains to battery-electric. There is a DOI of 10.1038/s41560-021-00915-5.
Nature Energy journal information.
There are battery-electric trains that can deliver environmental justice, cost savings and resilience to the U.S.
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