Toyota has long been an energetic advocate for hydrogen fuel cells as alternative to battery-powered electric cars, and is now looking into large, long-haul truck applications.

The Japanese automaker has formed a unit within its U.S. research and development facility in California to see if fuel cell technology is feasible for heavy-duty trucks.

“Toyota has long maintained that hydrogen fuel cell technology could be a zero emission solution across a broad spectrum of vehicle types,” the company said in a brief statement. “The scalability of this technology is enabling the automaker to explore a semi-trailer truck application for a California-based feasibility study.”

The Japanese automaker already sells the Mirai fuel cell passenger car in California and is set to put two fuel cell buses on the road in Japan next year, with plans for 100 of the buses in service for the 2020 Tokyo Olympic games.

SEE ALSO: Toyota Unveils a Fuel-Cell Bus

A heavy-duty semi truck sized fuel cell vehicle would solve the problem of how to clean up truck emissions.

According to the Union of Concerned Scientists, medium- and heavy-duty trucks produce about 20% of the greenhouse gases from the transportation sector.

Even though federal regulations have clamped down in recent years, trucks also produce a disproportionate amount of smog-causing oxides of nitrogen and particulates.

There are a mountain of challenges facing Toyota, however, not the least of which is the scalability of fuel-cell technology.

Fuel cell vehicles use a “stack” that combines hydrogen with oxygen from the air, and chemically coverts it to an electric current than can be used to operate electric motors like those found in an electric vehicle.

SEE ALSO: Pros and Cons of Hydrogen Fuel Cell Vehicles

Another issue is the lack of hydrogen refueling stations.

Currently, the Mirai and fuel cell cars from Hyundai and Honda are only sold in certain regions of California where hydrogen pumps are open to consumers.

Toyota isn’t the only company with its eyes on heavy-duty applications for fuel-cell technology.

Utah-based startup Nikola Motor Co. plans to debut a Class 8 semi tractor on Dec. 1 in Salt Lake City.