Toyota North America is moving forward with repurposing technology from its Mirai fuel cell passenger sedan to create a hydrogen power kit for heavy-duty trucks.

The automaker said Monday the California Air Resources Board granted a Zero Emission Powertrain Executive Order for the heavy-duty truck fuel cell electric powertrain. The order certifies a powertrain complies with emissions standards required for sale in California.

Toyota started experimenting with building a hydrogen fuel cell Class 8 truck in 2017. It used two fuel cell stacks from a Mirai sedan and a cab and chassis built by Kenworth to create a prototype truck.

Kenworth and Toyota jointly pushed the technology forward, building 10 trucks to run drayage routes from the ports of Los Angeles and Long Beach to inland Southern California destinations. The tests served as a proof of concept, and Toyota now plans to begin assembling new, more efficient fuel cell modules for hydrogen-powered, heavy-duty commercial trucks at its Kentucky plant later this year.

Toyota said the new powertrain offers improvements in energy efficiency and packaging size over earlier generations.

“We believe hydrogen will play a significant role in the emissions reduction of heavy-duty transport while not sacrificing the distance, power or fueling times needed to keep these fleet and individual operators running,” said Chris Rovik, executive program manager in Toyota Motor North America’s advanced mobiity division.

The hydrogen-fueled powertrain kit includes hydrogen fuel storage tanks, fuel cell stacks, batteries, electric motors and transmission, Toyota said.

Toyota declined to provide information about customers or pricing except to note that the kit will be eligible for California’s environmental incentives and makes up “another tool” for truck manufacturers and fleets to meet the state’s increasingly stringent emissions regulations.

Advocates of fuel cell trucks say the technology has several advantages over battery electric trucks, which are starting to roll out in fleets on the West Coast. Hydrogen trucks fuel quickly and would not create the delays of long battery charging time for truckers who must comply with federal limits on the number of hours they can drive daily. Fuel cell trucks also don’t need the giant, heavy batteries of an EV truck. In some instances, the extra weight of the battery pack can reduce the amount of cargo a truck can haul.

“Fuel cell technology is scalable, and we believe it will take an increasingly visible and important role in our collective fight to reduce and eliminate carbon as we move towards a hydrogen society,” Rovik said.

Toyota is a major proponent of hydrogen technology for fuel cell and combustion vehicles. Although the exhaust from fuel cells is only water, combustion engines that burn hydrogen emit nitrogen oxides but no carbon dioxide.

Other truck makers and auto companies see hydrogen as a promising zero or near-zero tailpipe emissions fuel.

Hyundai plans to unveil the production version of its Xcient fuel cell truck for the North American commercial vehicle market at the ACT Expo conference in Anaheim, Calif., May 1-4.

Hyundai said the Xcient already has more than 4 million miles of cumulative driving in commercial operations in Switzerland, New Zealand, Germany, Israel and South Korea. It also plans to outline its U.S. business strategy for the truck at the conference.

Meanwhile, Nikola Corp., a Phoenix, Ariz., startup, said it has orders for 100 Class 8 Tre hydrogen fuel cell trucks and plans to begin deliveries in the fourth quarter of this year.

Cellcentric, a 50-50 joint venture between Daimler Truck Group — the owner of the Freightliner brand — and Volvo Group, is also developing a fuel cell powertrain for heavy-duty trucks.

However, all of these plans depend on building a hydrogen fueling network in the U.S., especially along major trucking routes. According to the Department of Energy, there are only 60 fueling stations, mostly in urban California.