A handful of heavy-duty truck operators are hoping an early-stage startup can help lower the carbon emissions of their industry, one that has been particularly hard to clean up.

Companies including Ryder System Inc., Werner Enterprises Inc., NFI Industries, ArcBest Corp. and Cargill Inc. are planning to test a mobile carbon-capture system in development by Echeneidae Inc., which does business as Remora. The tests start later this year.

Remora’s 24-year-old chief executive and co-founder, Paul Gross, said he was surprised at how quickly he got interest from the trucking industry, where he knew no one as of last year. “I thought this would be one of the hardest parts of starting a company,” he added. Livonia, Mich.-based Remora, named after a suckerfish that clings onto sharks and cleans them, was incorporated in November.

Remora’s device is attached to the tailpipes of 18-wheelers with the intent of capturing as much as 80% of the emitted carbon dioxide. Remora then plans to sell the carbon dioxide for reuse. The technology is based on the doctoral dissertation of Christina Reynolds, a company co-founder and its chief science officer.

So far, carbon-capture aboard vehicles has gotten little commercial traction, largely because of the difficulty and added energy needed to store and transport the carbon dioxide that is generated at large volumes and weights, according to Thomas Bradley, department head of systems engineering at Colorado State University, who focuses on sustainable transportation and isn’t involved in Remora’s business.

Each gallon of diesel consumed, for example, results in about 20 pounds of carbon dioxide that must be stored on the vehicle, he said. “What can be equally challenging is the space that it takes,” he said, adding that the 20 pounds of carbon dioxide would occupy 1,000 gallons of space at exhaust pressures.

But Remora and its venture investors say this is the right time to pursue the technology given the holdups in production of electric trucks. Freight transportation accounts for 12% of all carbon dioxide emitted in the U.S., according to a Brookings Institution study. The trucking industry is facing government antipollution requirements as well as cargo customers eager to eliminate carbon from their supply chains.

“Everyone is trying to figure out how we comply with that,” said Karen Jones, executive vice president, chief marketing officer and head of new product development at Ryder, which operates a fleet of some 235,000 trucks.

Engineers David Griggs, left, and Yeabsera Kebede double-check wiring at Remora.

Photo: Marco Giannavola

Supply-chain snarls at electric-truck plants have been a particular obstacle in getting the vehicles on the road. Production of electric trucks at Tesla Inc., Nikola Corp. and others has been delayed.

“There’s a lot of talk about producing vehicles, but the actual production and delivery of vehicles is a different thing,” Ms. Jones said.

That is where carbon-capture technology comes in, she added.

“While I call Remora a little bit of a bridge to EV, it actually is more than a bridge,” Ms. Jones said. Ryder plans to test Remora’s device later this year at one of its locations in Kentucky. If the process meets standards, like not adding more than 10 minutes to the length of a trip, the company might order additional units, Ms. Jones said. Right now, it has ordered just one.

In addition to the pilot deal, Ryder also invested in Remora’s $5.5 million seed round, which closed in April. The financing was led by Union Square Ventures, with participation from venture firms Lowercarbon Capital, Y Combinator, First Round Capital, Neo Ventures and MCJ Collective.

Albert Wenger of Union Square Ventures, which led Remora’s $5.5 million seed round.

Photo: Gandalf Hammerbacher/Zuma Press

“In the near-term, Remora has one of the few truly credible strategies, which is to capture the CO2 for heavy-duty trucks,” said Albert Wenger, managing partner at Union Square Ventures. “The system will be saving net CO2 in very short order after being installed on a truck.”

While electric trucks are taking a while to become a conventional business, Remora still has to make the business and environmental case for its product.

The company’s onboard unit filters out carbon dioxide, compresses it and stores it in a tank. Periodically, the truck’s driver must unload the carbon dioxide to a stationary tank, where it is cooled and liquefied. A tanker truck would then pump out the liquefied carbon dioxide and transport it elsewhere for reuse.

Remora has yet to demonstrate the performance, efficiency and economics of its process, which involves additional infrastructure, as well as new tasks for drivers. The process could also add time to delivery schedules, creating more complications in supply chains.

Remora is charging its pilot customers $15,000 for each device, he said. The company expects to generate $14,000 or more from sales of the carbon dioxide per truck each year, and split that with the truck owners, Mr. Gross said.

Mr. Gross said he expects to get several hundred units on the road by the end of 2022.

“There are many unknowns,” Mr. Gross said, adding that the purpose of the pilot project is to prove its approach. But in comparison with heavy-duty truck electrification, he noted, carbon capture may have fewer weight and infrastructure constraints.

Write to Yuliya Chernova at yuliya.chernova@wsj.com