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Nature Energy Volume 6, Pages 1017–1025 (2021) Cite this article

Almost all American locomotives are driven by diesel-electric drives. Diesel-electric drives emit 35 million tons of carbon dioxide and generate air pollution, causing approximately 1,000 premature deaths each year and causing approximately US$6.5 billion in health damage costs each year. Improved battery technology coupled with access to cheap renewable electricity has opened up the possibility of battery-electric rails. Here, we show that a single standard boxcar equipped with a 14 MWh battery and inverter can achieve a cruising range of 241 kilometers while consuming half of the energy consumed by diesel trains. In the near future, if environmental costs are included, or railway companies can obtain wholesale electricity prices and achieve 40% of the use of fast charging infrastructure, then in the near future, battery electric trains can be on par with diesel electric trains. Taking into account the reduction of air pollutants and carbon dioxide emission standards, switching to battery-powered propulsion will save the US freight railroad department by US$94 billion within 20 years.

The scientific consensus asserts that by 2030, global greenhouse gas (GHG) emissions must be reduced by 45% from 2010 levels in order to limit global warming to 1.5 °C and minimize climate disasters1. The U.S. Freight Railroad provides a unique opportunity for aggressive near-term climate action. It transports more goods than any other railway system in the world2 and relies on diesel fuel, which accounts for more than 90% of the total energy consumption of the railway sector3. Currently transporting 40% of the national intercity freight4, its capacity is expected to double by 20505. Without substantial changes to its propulsion system, the US freight rail system will account for half of the diesel used by the global freight rail sector in the same year. These diesel locomotives emit 35 million tons of carbon dioxide each year and generate air pollution, causing approximately 1,000 premature deaths each year and causing approximately US$6.5 billion in health damage costs per year6,7. Although it is more fuel-efficient than trucks, due to the less stringent pollution control of locomotives, the air pollution loss per unit of fuel consumed by these locomotives is nearly twice that of heavy-duty trucks6,8. Since 2015, new locomotives and remanufactured locomotives have been required to install catalytic converters to reduce nitrogen oxides (NOx) and fine particulate matter (PM2.5) emissions by 80-90% by 20409. It is worth noting that these measures will not affect greenhouse gas emissions.

Efforts are being made to determine a zero-emission pathway for freight railroads, national emission reduction targets, and stricter Environmental Protection Agency (EPA) emission reduction requirements for the US freight railroad sector10. Some feasible ways to achieve zero emissions have emerged: the electrification of the railway network through the catenary, hydrogen fuel cells and battery-powered locomotives. The catenary method involves electrifying part or all of the railway network through overhead lines, combined with grid-scale renewable energy storage, and has been more thoroughly studied11,12. Hydrogen fuel cells have also received increasing attention13,14,15, although their zero-emission potential depends on the source of hydrogen and the process used to extract it16. Almost all hydrogen is currently produced from fossil fuels17. We are considering the battery power approach based on the use of recent technological advances to add battery vehicles to existing diesel-electric locomotives. This approach allows railway operators to develop existing surplus renewable energy at low prices.

Three recent developments support the transition to battery-electric railways in the United States: battery prices have plummeted, battery energy density has increased, and access to cheap renewable electricity. Between 2010 and 2020, battery energy density has tripled, and battery pack prices have fallen by 87% (Reference 18). By 2023, the industry average price is expected to reach US$100 kWh-1, and by 2030 it will reach US$58 kWh-1. Some automakers have realized the price of lithium-ion battery packs of US$100 kWh-1 (Reference 19). At the same time, the cost of renewable energy power generation is about half that of fossil fuel power generation20. Some studies have considered battery-electric rail propulsion, but due to the rapid innovation of battery technology, their price estimates are outdated, and they have not considered the impact of charging infrastructure capacity usage on infrastructure costs2,21. Previous studies also relied on average service level electricity prices, which overestimated the cost of charging because they did not consider the potential to charge batteries when there is surplus renewable electricity available, or consider transmission or distribution levels on routes with high levels Economies of scale of service travel volume.

On the basis of current and predicted energy storage technology, combined with the acquisition of renewable energy at industrial speed, we studied the case of zero-emission, battery-powered propulsion in the US freight railroad sector. We only consider Class I railways here, which are defined as railways with an annual revenue of more than US$505 million. These railways accounted for 94% of freight rail revenue in 201922. We show that a range of 241 kilometers (average distance traveled by American Class I freight trains per day) can be achieved using a single boxcar equipped with a 14 MWh battery and inverter, while consuming half of the energy consumed by diesel trains. Based on the recent battery price (100 kWh–1 USD), if environmental costs are included, or railway companies can obtain wholesale electricity prices and achieve 40% of the use of fast charging infrastructure, battery electric trains can be on par with diesel electric trains Taking into account the reduction of air pollutants and carbon dioxide emission standards, switching to battery-powered propulsion can save the US freight railroad department $94 billion in 20 years. We considered the sensitivity of our results to battery pack assumptions, electricity bills, and diesel prices.

Class I locomotives in the United States are diesel-electric: a diesel engine drives a generator that powers the traction motor to drive the axle. This type of locomotive can be converted to battery power by adding one or more battery-powered vehicles (called power-supply vehicles) with wiring to deliver power to the drivetrain. The trolley can transmit power to the central electrical bus of the locomotive through cables, and then transmit the power to the traction motor. Alternating current (ac) and direct current (dc) traction motors have different retrofit requirements; both types are used in American locomotives, although AC motors are becoming more common. DC locomotives only need cables and charge controllers from the battery trolley, and the cost incurred is negligible. Every locomotive equipped with an AC traction motor requires a transformer (we have considered this cost in the charging infrastructure in the electricity price) and an on-board inverter for the 3.3 MW traction motor. Alternatively, the traction motor can be added to the battery trolley as a cable-less locomotive (railway representative, personal communication).

The fuel efficiency of the rail freight sector (1-1 of diesel revenue tonne) is on average three to four times that of road freight4. This advantage provides the train with the margin required to increase the weight, volume and energy consumption associated with the battery to achieve sufficient daily mileage while maintaining a very high efficiency. In addition, battery technology and the nature of railway operations provide ample charging opportunities for long-distance transportation. Here, we show that adding a boxcar with battery equipment can enable battery-powered trains to reach the necessary operating range while surpassing the energy efficiency of diesel-electric trains.

Our analysis is based on a representative Class I train operating in California, where four 3.3 MW locomotives tow 100 freight cars and 6,806 tons of revenue (or payload tonnage). The standard 14.6-meter boxcar has a rated load capacity of 114 tons (Reference 23), although some heavy-duty carriages can carry up to 337 tons (Reference 24). We use lithium iron phosphate (LFP) batteries because they have a longer cycle life and a lower temperature 25 than nickel manganese cobalt oxide (NMC) batteries, and take into account the distance traveled by freight trains (2.4 million kilometers in 20 years) ) 26, so it is more economical. In addition, the service maintenance required for LFP batteries is negligible, the charging rate is as high as 4C (reference 27), which is cheaper than lithium titanate (LTO), and is not sensitive to unpredictable price fluctuations of cobalt or nickel 28 , And can operate in a wide range of temperature 29. Although LTO has some advantages over LFP, such as extremely fast charging, we choose LFP because of its lower price, higher energy density, higher voltage 30 and relative stability 31. Assuming the best energy density currently achieved by LFP batteries, a single boxcar can accommodate 14 MWh batteries and can travel 241 kilometers on a single charge, which is the average travel distance between US Class I freight train stops. Our estimate is much larger than existing estimates based on obsolete battery energy density, which suggests that a tender car can only carry 5.1-6.2 MWh (References 13, 32).

Using battery-specific energy data for LFP batteries and a typical packaging fraction (battery weight/battery pack weight) of 0.76 (reference 33), we estimate that the total weight of the 14 MWh battery plus the inverter is 114 tons, which is entirely in the US rail network 121 ton limit for certain parts, such as bridge 34. Assuming that the ratio of battery pack energy density (kWh l-1) to battery pack specific energy (kWh kg-1) is the same as the battery level, we estimate that the total battery volume is 39 m3. The total volume of the battery and inverter (13.7 m3) is approximately 40% of the estimated volume of a standard boxcar (129 m3) (Reference 23). Therefore, on the basis of weight and volume, it is feasible to use a single boxcar equipped with a 14 MWh battery and inverter to achieve a cruising range of 241 kilometers.

Due to the increase in battery weight, the energy consumption of battery freight trains has increased by 5% (241 km range), but due to the high efficiency of the all-electric drive, it is still about half of the energy consumption of diesel trains. After considering the industry’s average energy intensity35, diesel locomotive engine efficiency21, and battery cooling requirements, we estimate that a train with a cruising range of 241 kilometers (14 MWh battery) requires approximately 0.0345 kWh revenue-ton-km -1, LFP technology. In contrast, the current energy demand for battery-electric locomotives with regenerative braking is estimated to be 0.014 kWh tonne-km–1 (Reference 21). Japan’s existing passenger railway battery-electric locomotives have larger batteries in the operating range (for example, 3.6 MWh for a 27 km route) but the maximum range is not reported15. The preliminary findings of the California Battery Electric Locomotive Demonstration Project show that our estimate is reasonable (railway representative, personal communication).

Battery-powered trains with a cruising range of at least 241 kilometers should have ample opportunity to charge during long-distance driving while maintaining punctual driving. The average length of Class I freight in the United States is 1,662 kilometers (Reference 3). Class I freight railway routes include 30 to 45 minutes of stops every 240 to 400 kilometers for crew to change, at which time the batteries can be charged. Longer routes also include refueling at the midpoint for 1-2 hours (railway representative, personal communication). Although LFP technology can theoretically achieve 4C charging, technological advances have allowed the charging rate of commercial LFP batteries to be fully charged (1-2C charging) from 30 minutes to 1 hour. Although not taken into account in this analysis, the potential of replacing a discharged battery car with a charged battery car can provide additional flexibility for stations that are well-staffed and have sufficient daily traffic. There seems to be a significant downtime during which a charged car can be replaced with a discharged car, as the boxcar is usually idle for up to 25 hours at a time36.

The centralized and dispatching nature of freight railway operation and dispatch can achieve high utilization of fast charging infrastructure, thereby reducing costs. We estimated the cost of a 72 MW charging station connected at the transmission layer, which can charge eight cars at once (for example, two trains with four cars each). Using historical prices from Texas Electric Reliability Commission (ERCOT37) and California Independent System Operators (CAISO38), we estimate that the levelized cost of electricity plus charging is between 0.051 kWh-1 (60% use, ERCOT) and Between the US $0.185 kWh–1 (10% used, CAISO) (Figure 1). Paddeck et al. Discuss the impact of rate design on the cost of charges 39. Since these costs are shared by the number of trains using the charging station, the station with a larger number of trips may become the most cost-effective location.

a. Description of the ERCOT market, assuming that railway customers can obtain wholesale prices. b. Describes an illustrative CAISO market that assumes the CPP rate structure of ERCOT and does not have sufficient resource surcharges. Baseline assumptions include 80% charging depth, 8 bidding vehicles per station, 1 hour charging time, 7% capital expenditure income return53 and 10% power conversion efficiency loss. The life of the station is estimated to be 20 years. The power generation price is the average hourly price observed in each market during all the time of 2017-2019.

Based on the recent battery price (100 kWh–1 USD), if environmental costs are included, or railway companies can obtain wholesale electricity prices and achieve 40% of the use of fast charging infrastructure, battery electric trains can be on par with diesel electric trains The charging cost of pure electric trains includes charging infrastructure and electricity costs. The cost of charging infrastructure is mainly driven by its usage factors. We assume that 30-50% is used, this is due to the centralized dispatch of trains and the large amount of traffic on most routes13. Avoiding charging when electricity prices are high can reduce electricity bills. In some markets, such as ERCOT, demand and fixed transmission charges can be avoided by avoiding charging during critical peak pricing (CPP) times, which occurs in less than 50 hours per year37. In the past three years, the average wholesale power generation price in major US markets was less than 0.021 kWh–1 within 12 hours of the lowest price of the day (Table 1). We use these values ​​for the base case in the total cost of ownership (TCO) and net present value (NPV) calculations37,38.

Using the energy demand of 0.0345 kWh revenue-ton-km-1 of LFP batteries, we estimated the electricity price needed to achieve parity with diesel to realize the revenue of battery-powered trains with a mileage of 241 km-ton-1,090 tons. We estimate the capital cost of the required battery capacity and related charging costs, including battery weight, cooling requirements, and inverters. Figure 2 depicts the relationship between battery prices, diesel prices, and electricity prices required to promote the switch to battery-powered trains. In order to be equal to the diesel price reported by the railway industry in 2019 (the average price of diesel is 0.56 l-1 USD (Ref. 40)), the all-inclusive electricity price (generation plus amortized charging cost) must reach 0.056 kWh-1 USD, Close-the price of future LFP technology is 100 kWh-1; this calculation does not include environmental costs. Based on the average US diesel price (0.66 liters-1 USD), the electricity price of a 100 kWh-1 USD battery must reach 0.072 kWh-1 USD. In terms of context, the average industrial tariff in the United States is 0.064 kWh – US$1, excluding infrastructure costs41. If the main markets follow the tariff rules such as the CPP structure of ERCOT, if the freight railway reaches 40% of the charging infrastructure utilization rate, it can achieve a power cost of less than 0.07 kWh–1 US dollars (including the cost of charging infrastructure)-thus achieving the same The parity of diesel-powered trains. Including environmental costs, the necessary price of electricity plus charging infrastructure has been relaxed to achieve balance with diesel. Table 2 describes the input used to estimate the unit charging cost of the ERCOT market. The charging station can accommodate two trains charging at 1C at the same time.

These prices include the cost of electricity plus the cost of charging infrastructure, assuming that LFP technology is more than 20 years old. The battery prices considered are 200 kWh-1 (dark green), 100 kWh-1 (blue), and 50 kWh-1 (light green). The current electricity price is indicated by the blue shaded box. The vertical red line delineates the average diesel price paid by the railway industry in 2019. At the current wholesale diesel price of US$0.56l-1 and ignoring environmental damage, the all-inclusive electricity price will need to be close to 0.056 kWh -1 US dollars, the battery price is 100 kWh -1 US dollars, and the battery price is 0.074 kWh -1 US dollars. The price is 50 kWh in the United States – 1 to compete with diesel. These estimates are based on a locomotive with a range of 241 kilometers and a 9.1 MWh battery tender vehicle driving 1,090 tons of revenue. TCO is calculated annually with a discount rate of 3% in the range of 20 years.

Figure 3 shows the TCO of each locomotive in 20 years under the baseline scenario. Here, we apply the energy intensity of a representative line train in California (0.0345 kWh revenue-ton-km−1) to the average class I line train in the United States so that the results can be scaled up to approach the national cost of the transition to battery electric Freight railway. For more than 20 years, the cost of battery-electric bidding vehicles (including maintenance of existing diesel engines) has been US$6.4-800,000, and the cost of internal combustion engine vehicles has been US$585--11.83 million, depending on whether environmental damage is included. Table 3 describes the input parameters of the battery pack size.

a, TCO description of battery power propulsion. b, TCO description of diesel propulsion. It is estimated that both technologies use 9.1 MWh batteries and have a cruising range of 241 kilometers. They are used for 3.3 MW locomotives and can generate 1,090 tons of revenue. The assumptions include: 0.61 USD l-1 diesel price, 100 USD kWh-1 battery price (50 USD kWh-1 replacement price), 30% power station utilization rate and 3% discount rate. Under the battery-electricity scenario of CES90, the ReEDs model of the U.S. electric power portfolio is used to estimate environmental damage. Diesel engine damage is estimated under the assumption that EPA Tier 4 rules continue to be implemented. The social cost of carbon emissions will start from 125 t-1 USD in 2021 and will increase to 226 t-1 USD by 2040.

Table 4 describes the key input parameters used in the TCO analysis, representing current and near-term forecasted technologies and prices. The price of diesel we use is 0.61 liters-1 USD, which is between the fuel cost reported by the railways in 2019 and the average price in the United States. We include diesel engine maintenance costs into the TCO of battery-electric locomotives to maintain the flexibility of dual-fuel capabilities. If training operators choose to send battery tender vehicles to alleviate power constraints on the grid. Even the moderate price of external environmental damage is enough to make the battery price of battery-powered locomotives in the near future (100 kWh–1 USD) and the current electricity plus charging infrastructure price (US$0.070 kWh–1).

We investigated the NPV of the freight rail sector that has converted diesel-electric locomotives to battery power over the past 20 years, and compared capital and operating costs, as well as the cost of damage caused by CO2, and air pollutant standards. Although TCO compares each propulsion technology separately, NPV compares the industry-wide savings of battery electric versus diesel. If environmental factors are not taken into account, the NPV of the baseline battery power scenario will result in a cost of 15 billion US dollars, saving 44 billion US dollars when considering standard pollution reduction, and 94 billion US dollars in reducing carbon dioxide emissions. The main determinants of economic returns are station utilization and diesel prices. Our analysis shows that if diesel-electric trains internalize the cost of environmental damage, even if the battery price is 250 kWh–1 and the station usage rate is as low as 25%, then today's battery-electric trains are still cost-effective.

We analyzed the sensitivity of the results of the baseline battery power scenario to battery price changes, charging station capacity usage, diesel prices, battery life, and environmental damage. Figure 4 depicts the NPV range of each locomotive in 20 years for each input category. The biggest uncertainty in NPV is driven by charging station utilization and diesel prices.

The benchmark battery electric NPV is – 598,602 USD. Baseline assumptions include 9.1 MWh batteries, 100 kWh–1 battery prices, 30% power station utilization, 0.61 liters–1 diesel prices, 5,000 cycles of battery life, and zero environmental damage costs. Based on each input baseline battery-power scenario NPV change estimate, keep the baseline assumptions of all other components equal. The entered range is in parentheses. The gray bar represents the decrease in the locomotive NPV relative to the baseline assumption. The green bar represents the increase in locomotive NPV relative to the baseline assumption.

Catenary electrification is common in Europe and Asia. However, the context cannot be transferred directly, because the payload of American freight trains is often ten times that of European freight trains, greatly increasing the average power infrastructure demand32. Historically, it has been estimated that compared with Europe, the cost of electrification in the United States is about twice that in Europe, but due to the limited number of observations, these costs are very uncertain 42. In addition, the frequent use of double-deck containers in the United States makes catenary requirements a problem; the infrastructure needs to be 7 m higher than the track to accommodate such trains32. The recent cost estimates for catenary construction in the United States range from 5.1 million USD km-1 (Reference 43) to 31 million USD km-1 (Reference 21), excluding locomotive costs. However, these estimates only apply to passenger railways. International estimates are significantly lower. For example, the Norwegian government paid 1.76 million USD for the electrification of freight railroads. One advantage of battery-powered diesel locomotives is that the battery can simply be connected to an existing locomotive with an additional trolley instead of buying a new locomotive or upgrading the track. However, the cost of charging infrastructure accounts for a large part of the initial capital expenditure. Recent estimates have found that the current price of hydrogen fuel cell locomotives in the United States is almost half of that of battery-electric locomotives, but the cost will be the same by 2050. A more conservative assumption is used for battery tender vehicles (320 kWh-$1 battery price) , 1,500 cycles battery life and 5.1 MWh maximum capacity per tender vehicle) 13.

Our analysis provides preliminary evidence that—considering recent battery prices and wholesale electricity prices—renovating diesel-electric locomotives with battery-powered technology can save the U.S. freight railroad sector billions of dollars, while generating environmental, health, and grid resilience benefits. The average emission intensity of the US electricity mix is ​​383 kg CO2 MWh-1 (Ref. 44), which is expected to be reduced to 90% by 203545. Cost, zero-emission energy. The ability of electricity pricing policies, such as real-time pricing, must be further evaluated in order to use low-cost renewable electricity for battery-electric trains. In order to achieve diesel parity in the short term, this low-cost tariff is necessary. Or, corresponding air pollution damage charges or strict air pollution standards will minimize these damages, and the transition to battery electric trains can be realized. Such policy options must be evaluated in more detail.

A large number of locomotive batteries can be deployed to address location-specific grid constraints during extreme events. Even in places with electrified railways, if you encounter grid pressure with restricted locations, you can benefit from the mobile grid storage provided by battery supply vehicles. The battery-powered railway sector will have more than 200 GWh of modular and mobile storage, which has four advantages over typical grid-scale storage. First, locomotives will still be equipped with diesel engines, so the power system can use their batteries to manage extreme events. Second, unlike typical grid-scale storage, trains can move to address location-specific power system constraints. Third, because batteries are installed on rail cars and can be connected to or detached from freight trains, they can be flexibly deployed in the best locations for charging and discharging—charging in places where the price is low is the most popular on the power grid. Discharge in restricted places. Fourth, the four major players in the freight rail industry maintain 85% of the market share (Reference 46), and each participant can control a large amount of mobile energy storage, and decentralized storage ownership requires an efficient market for optimal use. Large-scale modularity and mobile storage from trains can support the power system in a variety of ways through appropriate vehicle-to-grid infrastructure, including supplying power to the grid during extreme price or demand events, supporting the temporary decommissioning of transmission and distribution (T&D) wildfires Infrastructure during the event and provide emergency backup power for critical loads in the event of a power outage. For example, preliminary estimates of the most expensive 90 hours per year on the ERCOT market indicate that batteries can be discharged at a price of 200 kWh – $1, and may generate enough revenue to cover up-front battery costs within a year37. It is necessary to plan and deploy a two-way charging infrastructure, and optimize grid services through the charging and discharging of battery-electric tender vehicles to obtain all the economic and environmental values ​​of battery-electric trains. Need to further study the deployment and operation of such infrastructure.

Although we estimate the battery size for the average daily freight train range, a smaller battery can greatly reduce the damage of air pollution. Assuming that most of the damage is caused by the concentration of population around railway stations, train operators may want to add enough capacity to run trains on battery power in these areas. As part of a project funded by the California Air Resources Board, the BNSF Railway is currently adopting this approach to reduce emissions around the railway yard47. Additional battery tender cars can be added to the composition (car sequence) to increase the mileage of the locomotive. Further research can provide insight into the optimal range of different stroke lengths and positions.

We estimate the levelized TCO for the conversion of the US freight railroad sector from diesel locomotives to battery-electric locomotives within 20 years. We start with the baseline scenario of average charging costs (including electricity bills and the cost of installing fast charging infrastructure), without considering environmental benefits, battery prices will not fall further. This scenario represents economics without any policy intervention in about 2023. We then considered the sensitivity of our results to changes in charging costs (reflecting the availability of low-cost renewable electricity), predicted battery price declines, and the value including environmental benefits. Real-time pricing and other policies can be implemented to achieve lower renewable electricity prices, linking electricity prices with wholesale market prices and environmental regulations, so as to obtain the economic value of environmental benefits39. For example, at certain times of the day, California has already observed such prices.

We estimate the battery size based on the specifications of the trains currently operating in California, representing a long-distance train consisting of four 3.3 MW locomotives with a load capacity of 6,806 tons21. Using the 0.059 kWh revenue-ton-km-1 diesel benchmark average energy demand and the relative efficiency of the battery power relative to the diesel engine, we estimate that each locomotive needs a 14-MWh battery to drive 1,701 revenue-a ton driving 241 kilometers using LFP technology. Due to the need to cool the battery system, the battery will cause a loss of efficiency. We upgraded the battery to meet the air conditioning requirements of the battery tender vehicle. We estimated the energy required to cool the entire boxcar to 15 °C in 12 hours a day.

We applied the previous research method on the electrification TCO of the truck transportation sector to the railway sector, and estimated the unit cost of charging as the sum of equipment leveling costs, power generation costs, and T&D costs. We model unit charging costs for retail customers who have access to wholesale energy prices in the ERCOT area. According to current regulations, this situation is realistic. The levelized cost of equipment is defined as the lowest price per unit of energy (kWh) that the charging service provider should charge consumers to achieve a balance of investment in charging equipment and grid interconnection39.

We use a direct energy balance method, using national data on train revenue ton-kilometers and diesel fuel consumption to estimate the energy required to transport the same payload under battery electric propulsion. To ensure that our industry results do not overestimate electricity demand, we use national average estimates to calculate industry costs, benefits, and emissions. California’s representative mainline locomotives used to estimate energy requirements tow 1,701 revenue tons, while the national average mainline Class I freight locomotive only carries 1,090 revenue tons. After making adjustments based on battery weight and cooling requirements, we estimate that each locomotive's load requires 9.1 MWh of batteries.

Every locomotive equipped with an AC traction motor requires an on-board inverter for a 3.3 MW traction motor at a price of 70 kWh–1 (Reference 48). We borrow existing methods to estimate the cost of charging including electricity and fast charging infrastructure costs. The cost of equipment per kilowatt hour decreases with capacity usage, which is defined as the number of hours used per day 39. Assuming a capacity utilization rate of 50%, the amortized cost of fast charging infrastructure plus energy is 0.048 kWh – 1 USD. We estimated a low-cost scenario of 0.048 kWh–1 (50% capacity usage) and a high-cost scenario of 0.07 kWh–1 (25% capacity usage), including the levelized cost of fast charging infrastructure. Given the flexibility of charging time, we expect train operators to get the lowest energy prices.

We estimate our baseline scenario with a battery price of 100 kWh–1 USD. Data from China, which has the largest number of heavy-duty electric vehicles (HDEV), shows that the price of batteries for buses and other heavy-duty electric vehicles is slightly lower than the average price of batteries for light-duty electric vehicles (LDEV) in China and the world19. Although the difference in average battery pack prices between China and the rest of the world is partly due to their use of different types of battery chemistries, China's HDEV production is much higher than any other country in the world. Therefore, with economies of scale, the price of the battery pack of HDEV in the United States is likely to be close to that of the LDEV battery pack. Others also said that this kind of economies of scale may soon appear in the HDEV industry49,50. We calculate the environmental impact by comparing diesel emissions with baseline emissions for power generation using projected US emissions. Under the scenario of 90% clean energy by 2035, the National Renewable Energy Laboratory's Regional Energy Deployment System (ReED) model 51 is used to model national emissions45. Using the estimated median loss of locomotives in 20116, combined with the EPA's estimated NOx and PM2.5 emission reductions based on the existing locomotives' Tier 4 requirements, we predict the total loss of standard pollutants, assuming that PM2.5 and NOx are linear Decrease, which corresponds to the existing predicted trajectory 7.

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The following authors received funding for this work from the Hewlett Foundation, grant number 2019-9467: NP, ET, and APJ Zuboy provides unparalleled editing capabilities to enable readers to understand this article. Representatives from BNSF, Wabtech, California Air Resources Board, Tesla, Southern California Edison, and California Energy Commission each provided constructive feedback to inform us of the basic assumptions of the analysis.

Energy Analysis and Environmental Impact Division, Energy Technology Field, Lawrence Berkeley National Laboratory, Berkeley, California, U.S.

Natalie D. Popovich and Amorfadek

Institute of Environment and Sustainable Development, University of California, Los Angeles, California

Department of Agriculture and Resource Economics, University of California, Berkeley, California

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AP conceived the idea and guided the project. NP analyzes, improves methods, organizes data, and writes drafts. DP has developed a method for levelling the cost of charging infrastructure. ET collected preliminary data and conducted a preliminary analysis of the working document version of this manuscript.

The author declares no competing interests.

Peer review information Nature Energy thanks Federico Zenith and other anonymous reviewers for their contributions to the peer review of this work.

The publisher states that Springer Nature remains neutral on the jurisdiction claims of published maps and agency affiliates.

Data and calculations for estimating charging costs.

Data and calculations used to estimate battery size and TCO.

Used to enter environmental damage data.

Historical CAISO prices in 2017, 2018, and 2019.

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Popovich, ND, Rajagopal, D., Tasar, E. etc. The economic, environmental and grid restoration advantages of converting diesel trains to battery electric. National Energy 6, 1017–1025 (2021). https://doi.org/10.1038/s41560-021-00915-5

DOI: https://doi.org/10.1038/s41560-021-00915-5

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