Article provided by Lawrence Berkeley Laboratory.
The trains were on the sidelines Electricity efforts are long overdue in the US because they account for only 2% of transportation sector emissions, but 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, resulting in an estimated 1,000 premature deaths each year. Moreover, these deaths and adverse health effects disproportionately affect disadvantaged and low-income communities, which are more likely to be located near rail and railway yards.
The recent big drop in battery prices has created a new possibility for freight trains to be electrified. Researchers from the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Laboratory), in collaboration with UCLA and UC Berkeley researchers, have demonstrated that the United States can modify diesel and battery-electric trains in a cost-competitive manner with diesel. Doing so will avoid these unnecessary deaths and health impacts and save $94 billion to the US freight rail sector over 20 years of reduced air pollution and carbon dioxide emissions. Their study was recently published in the journal nature energy.
“Rapid transformation of the freight and rail sector is not only technically feasible and cost-effective, but will bring immediate and lasting health and economic benefits to low-income communities,” said Natalie Popovich, Berkeley Lab scientist and lead author of the study. This will provide a boost to our country’s efforts to reduce climate change, particularly given that freight rail capacity in the United States is expected to double by 2050.”
Trains play an important role in moving goods around the United States, especially heavy cargo such as coal, lumber, and ore. According to the Federal Railroad Administration, 28% of American freight across the country is carried by rail, and this percentage is expected to grow exponentially in the next two decades. At the recent United Nations Climate Change Conference for 2021, the United States joined dozens of other countries in signing new agreements to reduce freight emissions, and zero-emissions solutions for freight rail will be part of that commitment.
Diesel – electric, but not battery – electric
Unlike many other regions of the world, all freight trains in the United States are still diesel-electric, in large part because the typical electrification strategy of building electrified lines over tracks is difficult to implement in the United States with its vast distances. In diesel-electric trains, a diesel engine is connected to an alternator which then supplies electricity to electric motors connected to the locomotive’s axles. Thus, modification of battery-powered trains is possible because diesel and electric trains already have an electric motor.
“Massive improvements in battery technology, combined with the current electric propulsion system in diesel-electric freight trains in the United States, are paving the way for a rapid transition to electric battery freight rail with significant cost savings,” said Berkeley Lab scientist, Amol Fadek. , the corresponding author of the study. “Also, the weight of the batteries is less complicated than the weight of electric cars or trucks. We can add a car to a freight train built with batteries, and the weight of that battery-powered car is not an issue with trains.”
Diesel-electric trains have been around since the 1920s, and began to replace steam trains in the 1930s as they performed better and were less polluting. At the time, it was cheaper to use diesel engines to power the engines in trains than trying to develop fully electric trains due to the high costs of electricity. Now, a century later, we are at a point where the price of electricity is competitive with diesel, and the environmental and health costs of continuing to rely on diesel to power freight trains are too devastating to ignore.
“Our analysis shows that switching to electric battery charging will cut the industry’s annual CO2 emissions by more than half, eliminating more than 400 million metric tons of CO2 in 20 years,” Popovich said.
The study highlights the existence of additional pathways to electrify US freight trains, such as electric trains via overhead power lines or the use of hydrogen fuel cells in conjunction with battery-powered trains. However, based on the fact that freight trains are already diesel-electric, and given recent advances in battery technology, the researchers demonstrate that the battery-electric route offers the most cost-effective and long-lasting solution with many additional benefits.
Their analysis shows that current battery technology can power a freight train for 150 miles (the average daily distance traveled). A battery-powered freight train will use half the energy a diesel-electric train needs, and taking into account the lower battery prices and environmental costs of diesel, battery-electric trains are on track to be more cost-competitive than diesel-electric trains. Since freight railway planning is centralized, the study indicates that railways can make significant use of fast freight infrastructure, which will reduce costs.
Battery-powered vehicles are modular and can be deployed in various configurations for locations experiencing blackouts as well as in other sectors, such as electric ships.
One of the main benefits of modifying diesel-electric freight trains with battery-powered cars – otherwise known as battery cars – is that battery-electric trains can always count on the diesel engine as a back-up fuel source. This dual-fuel capability, which allows the use of a battery or diesel, is a unique advantage compared to the full electrification of the freight rail system or the use of hydrogen fuel cells.
Standard batteries offer flexibility benefits
Another major benefit is that battery-powered electric trains can be deployed as clean backup power, thus enhancing the resilience of the electric grid. Historically, diesel and electric trains were used as power generators during emergencies. In early 1998, a series of ice storms left more than a million without power in the northeastern United States and in parts of Canada. In a Montreal suburb, the mayor moved an all-electric diesel locomotive near City Hall to provide power for emergency response operations.
With the escalation of extreme weather events and power outages, battery-powered trains could be deployed nationwide to avoid power outages. These modular battery cars can be moved where they are needed and charged in locations where electricity prices are low, providing significant advantages over grid-scale storage. Furthermore, battery-powered cars could serve as modular shipping containers, capable of interchangeable between freight rail and sea freight vessels, with positive decarbonization benefits for both sectors and expanded flexibility.
“Converting the US freight rail sector to battery electric will generate about 220 gigawatt-hours of mobile storage,” Phadke said. Moreover, these battery-powered cars can be deployed during extreme events, such as the recent catastrophic wildfire in California or the 2021 Texas winter storm that left millions without electricity. This mobile energy storage capacity will also create a potential new revenue stream for freight rail operators.”
From a technical perspective, the researchers explained that there should be no restrictions in transitioning to fully electric battery-powered freight trains, but that more research and large-scale demonstration projects are needed to improve the freight infrastructure. “Berkeley Lab’s systems and market analyzes shed light on this neglected area and show that we can decarbonize some sectors using existing technology, which will help us reach our climate goals faster while enhancing environmental equity and network resilience,” said Noel Bekhtian, director of the Storage Center. Energy at Berkeley Lab, “It’s a win-win.” “Technical and economic analysis of battery-electric freight trains shows that we have viable solutions available to enable the transition to a clean, affordable, and resilient energy future.”
The research was supported by the William and Flora Hewlett Foundation, via the Berkeley Lab Foundation.
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