When it comes to improving efficiency and reducing emissions in transportation, often the answer is to take what’s old and replace it with something entirely new, such as buying an electric vehicle.

Atlanta-based Norfolk Southern and manufacturing giant Alstom are testing a different approach: retrofitting a pair of half-century-old locomotives with a new hybrid electric propulsion system that the railroad says will improve efficiency while reducing pollution and noise.

Norfolk Southern, like many major corporations, has committed to reducing its carbon footprint and boosting sustainability as it confronts business risks from climate change. Among the company’s goals is to boost locomotive fuel efficiency by 13% by 2027 and increase its renewable energy use by 30% by 2030.

The railroad has commissioned Alstom to take two diesel-powered locomotives and replace the guts of the hulking engines with battery packs. New, smaller Cummins diesel engines will be installed in each to recharge the batteries, which also can be plugged in.

“Think of it as a 200-ton Toyota Prius,” Norfolk Southern Chief Sustainability Officer Josh Raglin told The Atlanta Journal-Constitution.

The two hybrid locomotives will undergo conversion in western New York and are expected to enter service in 2026 or 2027. The locomotives will be used within rail yards in upstate New York to help move railcars and assemble or disassemble trains. Raglin said they also will be used to pull freight on short-haul routes.

Funding for the project will come from multiple sources, including $5 million from Norfolk Southern and a $16 million grant from the Federal Railroad Administration. The Steuben County, New York, Industrial Development Agency and Binghamton University’s New Energy New York consortium are also providing assistance.

Norfolk Southern started testing fully electric trains more than 15 years ago, and a number of companies are investing in them. But Raglin said the hybrid approach might be a better alternative. For instance, Raglin said battery-only locomotives require huge electrical grid capacity.

Alstom’s hybrid technology is used in Europe, but Raglin said Norfolk Southern’s pilot program will be the first time it’s been deployed on North American freight trains. The hybrid system can be plugged in to recharge, but the burden on the grid is far lower than for a fully electric locomotive, he said.

Taking an existing locomotive and converting it to a hybrid drivetrain is also far less carbon-intensive than building a new locomotive from scratch, Raglin said.

Hybrid propulsion is expected to reduce emissions by 90%, while improving pulling power by nearly one-third, meaning the locomotives will be more fuel efficient. And that’s a big consideration for a company like Norfolk Southern.

Fuel is the company’s second largest expense behind personnel.

“It’s not only good for the environment but good for the company as well,” Raglin said.

The company expects the hybrid locomotives to require less maintenance, another cost savings. The Alstom system is also modular, meaning that as the technology improves, components can be replaced.

Rail is the most sustainable form of ground-based transportation, Raglin said, with one train able to take some 300 to 400 trucks off the road. But taking carbon out of freight rail is a difficult task.

In a news release, Eric Rondeau, leader of Alstom’s innovation center for sustainable mobility solutions in North America, said “decarbonizing the rail industry is a huge challenge, and this grant will support critical strategic collaboration and shared expertise needed to innovate new sustainable technologies.”