Toyota Mirai review: A futuristic, super-smooth hydrogen fuel cell carAn 80,000lb (36,288kg) Class-8 tractor-trailer combo using a development fuel cell drivetrain from two small Toyota Mirai sedans? Surely, I’ve been dropped into the way-far future of Logan’s Run. But no, it turns out Toyota’s future-trucking idea resides at California’s Port of Long Beach, where 18,630 shipping container units get processed per day. That’s almost one in five containers moving anywhere in the entire United States. In shipping terms, Long Beach is to shipping what Atlanta’s Hartsfield-Jackson is to airports, making it the largest and likely best test lab for such a project.
Two years ago, Toyota began secretly testing a hydrogen fuel cell system alternative to the conventional diesel powertrain for heavy Class-8 trucks. Called “Project Portal,” this system is intended for drayage (short-haul movements), shuttling shipping containers between Los Angeles and Long Beach ports plus other freight depots. Toyota is the first major car company to dip a toe in the fuel cell trucking waters, and it could eventually market the powertrains to various truck manufacturers nationwide or through its own Hino truck division. (Toyota used a Kenworth to demonstrate the powertrain; however, Hino does not make a Class-8 rig.)
Though other companies have researched either electric or fuel cell heavy-duty trucking—Mercedes placed medium-duty trucks in controlled fleets this year in Europe, for example—none have pulled the fuel cell trigger in the US.
Why? Some emissions basics
Carbon dioxide, oxides of nitrogen, sulfur dioxide, and other pollutants are all byproducts of diesel trucks, scores of which concentrate at the Port of Long Beach. And these vehicles operate day and night. Air quality in the immediate vicinity of Long Beach has always been poor, a byproduct of the billions of dollars’ worth of goods funneling through the vast complex.
And since short-haul trucks need not have immense range between refueling, it made this particular lab experiment the right one to prove the zero-emissions truck concept for Toyota. According to some studies, more than 30 percent of California’s NOx emissions come from commercial heavy-duty vehicles. Because hydrogen fuel cell powertrains produce no tailpipe emissions, they are a very attractive solution despite infrastructure limitations for hydrogen fuel.
This could lead to further research in other heavy-duty Class-8 usage, but only once the limitations of an absent distribution network of hydrogen fueling stations is resolved. For the Port of Long Beach, though, Toyota’s installing a hydrogen refueling station on-site.
Diesel no more
The Portal Project truck uses a Kenworth T660 chassis and body because it represents a fairly common drayage truck. Toyota fits two Toyota Mirai drivetrains running in series, with two fuel cell stacks linked up to two batteries and two motors. Battery output from the pair of connected lithium-ion units is 12kW total, and the Mirai stacks generate 114kW each. Total system power equates to 670hp (500kW) and 1,325lb-ft (1,796Nm) of torque, roughly equivalent to the latest Cummins diesel in use today. Also, Toyota claims the rig can maintain speed on uphill grades of up to 12 percent.
“The two Mirai power control units sit in front, with two fuel cell stacks side by side under the cabin,” said Takehito Yokoo, Toyota’s senior executive engineer for advanced fuel cell development. “Four hydrogen tanks are installed behind the cab where the truck’s sleeping berth would normally be located. The connected batteries are also located near the tanks because there is ample space there, especially when there is no sleeping berth [which is not needed for short-haul duties].” As part of ongoing development, Toyota will look to relocate that conjoined battery lower in the chassis.
“Mating the two power systems together requires a lot of software development and ensuring communications between components in the right way,” Toyota’s Craig Scott, director of the advanced technologies group, told us. “The big variable in this project is basic engineering, like where to place the major components—the tanks, the battery, the stacks, the hydrogen pumps—but the nice thing with it being a Class-8 truck is that there’s lots of room. It’s a large canvas. This is really just the first step in our proof-of-concept to marry these powertrains into this body and be able to perform and tow at the standard of a diesel without any consideration for optimization.”
These fuel cell stacks are also far smaller than batteries that store electricity, the kind that would be used in a plug-in electric truck. In addition, refueling here is far briefer than recharging batteries, and the truck can do 200 miles fully loaded to 80,000lbs (36,288kg) before needing to refuel.
Since fuel cells operate at around 90 degrees Celsius, where an internal combustion engine runs at a maximum of about 300 degrees Celsius, cooling needs are vastly different, including having an entirely different surface area to cool. Therefore, Toyota uses two Mirai heat exchangers.
“We’ll monitor those temperatures and other data through telemetry during development,’ notes Scott. “We’re treating this like any other vehicle development program, actually. The next phase will see multiple computers inside the cab of the truck to log data and monitor conditions as it’s tested.”
With infrastructure needs addressed—again, this is no small feat—eventual implications for this type of fuel cell power for commercial trucking could eventually expand greatly. Toyota may be progressing this market toward a watershed moment.
Listing image by Toyota
More Info: arstechnica.com