California adopts first-ever rules to decarbonize freight trains

All new locomotives operating in California will have to be zero-emissions by 2035. But rail operators say the technology isn’t ready to roll just yet.
By Maria Gallucci

  • Link copied to clipboard
A yellow locomotive with a Union Pacific logo pulls rail cars down the train tracks
(Eddie Bugajewski/Unsplash)

Tens of thousands of locomotives chug along U.S. railroads every year, pulling cars full of grains, metals, chemicals and lumber. Thousands more switcher” trains shuffle cars in and around rail yards. Today, nearly all of those powerful engines run on diesel.

In California, however, that could soon start to change.

Last week, the California Air Resources Board (CARB) adopted first-in-the-nation rules that aim to dramatically slash air pollution and planet-warming emissions from the state’s rail sector. Along with imposing short-term measures, the policy states that any locomotive built in 2035 or after will have to use zero-emissions configurations” while operating in California, even if coming from another state.

The clean-air agency adopted the rail regulations the same day it unanimously approved an Advanced Clean Fleets rule, which calls for converting California’s fleet of 1.8 million commercial trucks to emissions-free vehicles over the next two decades.

Locomotives are a key part of California’s transportation network, and it’s time that they are part of the solution to tackle pollution and clean our air,” CARB Chair Liane Randolph said in a statement on April 27.

CARB said its locomotive rules could reduce fine particulate matter from locomotives by 91 percent by 2050, compared to the projected 2025 baseline. Nitrogen oxide levels could fall by 86 percent over the same period. Both forms of pollution can contribute to or exacerbate chronic health conditions, such as asthma and heart disease — particularly within neighborhoods surrounding busy railyards.

Diesel exhaust is one of the most dangerous things that we can breathe in,” Yasmine Agelidis, a lawyer with the environmental nonprofit Earthjustice, told Canary Media. When CARB adopted this rule, they really committed to cleaning up this industry that has been polluting our communities for decades.”

A bar chart shows the projected emissions reductions in PM2.5 pollution among five locomotive types
“Line-haul” locomotives, which haul freight over long distances, are responsible for the bulk of fine particulate matter (PM2.5) pollution in California. (CARB)

But exactly how California will achieve these ambitious new goals is still an open question.

Alternative technologies, such as battery-electric and hydrogen-powered locomotives, are in their relative infancy. And the nation’s railroad operators have long resisted efforts to electrify tracks — as many other countries have done — leaving the United States with diesel-dominated infrastructure.

Opponents of the new rules, including the Association for American Railroads, say CARB’s decision isn’t rooted in reality.

The regulations fail to take into consideration that the technology and infrastructure needed for success do not exist,” a spokesperson for Union Pacific said by email. Union Pacific is the nation’s second-largest railroad operator after BNSF Railway. The two companies are also California’s top operators.

Despite this stance, railway operators themselves are already developing the very technologies needed to slash emissions from diesel locomotives.

In September, BNSF Railway ordered four battery-electric locomotives from the manufacturer Progress Rail to replace older diesel units in Southern California. The first of the 8-megawatt-hour locomotives is expected to be delivered later this year and will run a 240-mile route between Los Angeles and Barstow — making it the first zero-emissions locomotive of its kind to operate in California, according to the South Coast Air Quality Management District, which is partially funding the project.

Union Pacific said it’s investing over $1 billion to modernize” 600 of its locomotives, which includes updating equipment to improve fuel efficiency, reliability and haulage capacity, making it possible to carry more freight in fewer trips. Last year, the Omaha-based operator also announced plans to purchase 20 battery-electric locomotives for testing in rail yards in California and Nebraska, starting in 2024. The cost of buying the locomotives and upgrading the rail yards’ electrical infrastructure is expected to exceed $100 million.

A red-and-gray locomotive is stationed on a railroad track.
BNSF Railway and Wabtec pilot-tested a battery-electric locomotive in California in 2021. (Wabtec)

Wabtec Corp., a leading maker of freight locomotives, will supply half of those new trains. In 2021, the manufacturer unveiled what it called the world’s first battery-powered freight locomotive, which was developed with a $22.6 million grant from CARB.

Its locomotives will have a 2.5-megawatt-hour battery capacity. Regenerative braking can partially recharge the batteries, though the trains will also be able to use direct-current fast charging, either by plugging into charging stations or using stationary pantograph” devices mounted to their roofs.

Wabtec is also exploring the use of hydrogen in freight engines. The zero-carbon fuel is much earlier along the development curve than batteries when it comes to locomotives.

In Europe, a handful of passenger trains use fuel cells powered by hydrogen gas, and Alstom, a leading French manufacturer, has plans to expand across the region. But freight trains tend to travel longer distances and use multiple engines, meaning that their fueling needs are much larger than those of shorter-distance commuter or passenger trains. Manufacturers are considering using liquid hydrogen — which takes less room to store than gas — and burning it in combustion engines.

However, there’s another way to decarbonize the rail sector that’s already well established and widely deployed in other parts of the world: electric railroads. Agelidis of Earthjustice said her organization wants California’s operators to pursue this approach, in large part because the technology is available today.

Railroad operators can electrify networks with overhead catenary lines or conductive third rails. About one-third of the world’s track miles are electrified, though in Europe, Japan and Korea, the percentage is around 60 percent. Still, converting existing tracks can be prohibitively expensive for operators, particularly where long-distance and infrequently used networks require new infrastructure.

CARB’s new rules will still need approval from the U.S. Environmental Protection Agency, which can issue waivers allowing California to set and enforce more stringent standards than the federal government. If adopted, other states could follow California’s lead — accelerating clean-rail efforts that by now are nearly two decades in the making.

Going forward, in the next few decades, we’ll have zero-emissions trains, and that’s what we’re really excited about,” Agelidis said.

Maria Gallucci is a senior reporter at Canary Media. She covers emerging clean energy technologies and efforts to electrify transportation and decarbonize heavy industry.