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Railroads converting to batteries could save $94 billion in two decades

Berkeley National Lab says, U.S. Class 1 railroads converting to batteries could save $94 billion over 20 years and reduce pollution.

If U.S. Class 1 railroads convert from diesel locomotives to battery power, they can save $94 billion over 20 years “while consuming half the energy consumed by diesel trains,” according to a Lawrence Berkeley National Laboratory report.

The report, “Economic, environmental and grid-resilience benefits of converting diesel trains to battery-electric” was published in the November, 2021 issue of Nature Energy.

The report argues the Class 1 railroads can become a leader in battery-powered conversion for freight transport because of the fuel-efficient nature of their long-haul operations:

“The freight rail sector is three to four times more fuel efficient … than road-based freight, on average. This advantage provides trains with a margin for adding the battery-related weight, volume and energy consumption needed to achieve a sufficient daily range while maintaining very high efficiency. In addition, the nature of battery technology and rail operations provides plentiful opportunities for recharging during long hauls.”

Rail Conversion to Batteries Is Now Feasible

The Lawrence Berkeley National Laboratory report, authored by Amol Phadke and colleagues, outlines their plan for Class I railroads to convert to batteries and reduce energy costs. The authors argue that projected technology price declines will soon result in battery-powered trains being cost-competitive with diesel-powered trains:

“Here we show that a 241-km (150 mile) range can be achieved using a single standard boxcar equipped with a 14-MWh (mega-watt/hour) battery and inverter, while consuming half the energy consumed by diesel trains.

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.

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.”

The rapid transition is possible, because diesel electric locomotives can be converted to battery power:

“US Class I locomotives are diesel-electric: a diesel engine drives an electric generator that powers traction motors to drive the axles. Such a locomotive can be converted to battery-electric by adding one or more battery tender cars, referred to as tender cars, with wiring that delivers electricity to the drivetrain. A tender car could transmit electricity via cable to the locomotive’s central electrical bus and then transmit that electricity to the traction motors.”

Improvements in Battery Technology Reduce Costs

The report explains that there have been major improvements in battery technology that make the conversion to battery power economically viable:

“Three recent developments support a US transition to battery-electric rail: plummeting battery prices, increasing battery energy densities and access to cheap renewable electricity.”

These developments support the conversion of diesel locomotives to battery power:

“Between 2010 and 2020, battery energy densities tripled and battery pack prices declined 87%. Average industry prices are expected to reach US$100 kWh–1 by 2023 and US$58 kWh–1 by 2030, with some automakers already achieving lithium-ion battery pack prices of US$100 kWh–1. At the same time, electricity from renewable sources costs about half as much as electricity from fossil fuels.”

The Lawrence National Laboratory report says that efforts to identify zero-emissions pathways for freight rail are underway, with national sector-wide emissions-reductions targets and “more stringent Environmental Protection Agency (EPA) emissions-reductions requirements for the US freight rail sector.”

BNSF and Wabtec commence battery-electric locomotive pilot test in California
BNSF and Wabtec commence battery-electric locomotive pilot test in California

BNSF Battery-Powered Project Reduces Pollution

A collaboration between the Burlington Northern Santa Fe railroad and the California Air Resources Board is underway to reduce pollution in populated areas that also suggests a strategy for railroads to transition from diesel power to battery power:

“Although we estimate battery sizes for average daily freight train ranges, much smaller batteries can substantially mitigate air pollution damages. Assuming most damages result from concentrated populations around railyards, train operators may wish to add just enough capacity to run trains on battery power in these areas. BNSF Railway is currently pursuing this approach as part of a project funded by the California Air Resources Board to reduce emissions around railyards. Additional battery tender cars could be added to the consist (sequence of cars) to increase the range of the locomotive. Further research could provide insight into optimal ranges for different trip lengths and locations.”

Urgency of U.S. Railroads Reducing Pollution and Global Warming Emissions

There is an urgent need for U.S. Class 1 railroads to convert to renewable energy as their operations are a major generator of greenhouse gas (GHG) emissions, such as carbon dioxide (C02), that contribute to global warming. While locomotives are more fuel-efficient than trucks, they generate more pollution due to less regulation:

“The US freight rail sector provides a unique opportunity for aggressive near-term climate action. It transports more goods than any other rail system in the world and depends on diesel fuel, which accounts for over 90% of the rail sector’s total energy consumption. Currently transporting 40% of national intercity freight, its capacity is projected to double by 2050. Without substantial changes to its propulsion system, the US freight rail system will be responsible for half the global diesel used in the freight rail sector by the same year. These diesel locomotives emit 35 million tonnes of CO2 each year and produce air pollution that causes about 1,000 premature deaths annually, accounting for approximately US$6.5 billion in health damage costs per year.

Despite being more fuel efficient than trucks, these locomotives produce close to twice the air pollution damages compared with heavy-duty trucks per unit of fuel consumed owing to less stringent pollution controls on locomotives. Since 2015, new and remanufactured locomotives have been required to install a catalytic converter, reducing nitrogen oxides (NOx) and fine particulate matter (PM2.5) emissions by 80–90% by 2040. Notably, these measures do not impact GHG emissions.”

Methodology Driving Conclusions

The authors described the methodology by which they developed their conclusions:

“Our analysis is based on a representative Class I train operating in California, with four 3.3-MW locomotives pulling 100 boxcars and 6,806 revenue-tonnes (or tonnes of payload). A standard 14.6-m boxcar has a rated payload capacity of 114 t, although some heavy-duty cars can carry up to 337 t.

We use lithium ferrous phosphate (LFP) batteries because they have a longer cycle life and lower temperatures than do lithium nickel manganese cobalt oxide (NMC) batteries and are more economical given the distances travelled by freight trains (2.4 million km over 20 years). Furthermore, LFP batteries require negligible service maintenance, have a recharge rate up to 4C, are cheaper than lithium titanate oxide (LTO), are not sensitive to unpredictable price fluctuations in cobalt or nickel and can operate over a wide range of temperatures.

While LTO presents some advantages relative to LFP, such as extreme fast charging, we select LFP due to the lower price, higher energy density, higher voltage and relative stability.”

Assuming the current best energy density achieved by LFP batteries: “a single boxcar could accommodate a 14-MWh battery with a 241-km range on a single charge, the average distance travelled between stops for US Class 1 freight trains. Our estimate is much larger than existing estimates based on outdated battery energy densities that suggest a single tender car could carry only 5.1–6.2MWh.”

Stas Margaronis
Stas Margaronis


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