Challenges in operating hydrogen trucks in extreme cold

One of the Nikola FCEV trucks used by AMTA in its cold-weather trials. (Photo: Alberta Motor Transport Association)

In addition to addressing driver education, training and advocacy, Canada’s Alberta Motor Transport Association (AMTA) has a research and innovation arm. In a recent Mission Hydrogen webinar, AMTA reported on research it has done regarding the viability of hydrogen in Class 8 trucks — both hydrogen-diesel dual-fuel and hydrogen fuel cell electric vehicles — in the province’s extreme cold weather conditions. AMTA has done trials with more than 20 carriers using Hydra Energy dual-fuel trucks, Hyzon FCEVs and Nikola FCEVs.

Jamie King, who works in research and development for AMTA’s industry and advancement group and is the organization’s subject matter expert on hydrogen trucks, addressed issues related to both fueling and vehicle operation. Power Progress recently reported on AMTA’s learnings about fueling with hydrogen in extreme cold. Regarding FCEV truck operations, King identified four key areas of focus.

Before the Trip

Addressing the challenges related to operating a FCEV in bitterly cold weather begins the moment the driver reaches the vehicle, King said.

“Typically, a driver will perform a walk-around and inspect the truck prior to turning it on and then complete any pre-trip inspections once the vehicle is started and warming up for the day,” she said. “Hydrogen trucks will take substantially longer to warm up in the cold — upwards of 20 minutes to half an hour on a particularly cold day.”

That assumes that the truck will start in the first place, King said. She added that a temperature of -20°C (-4°F) is the point at which hydrogen trucks tend to either break down or underperform.

“We have found that below - 20°C (-4°F), and -25°C (-13°F) — we can sometimes get to that — the trucks are unlikely to even come close to starting,” she said.

That isn’t to say that AMTA has not taken steps to mitigate this issue.

“Some of our trucks have e-axle heaters that require plugging in,” King said. “Some also require a trickle charger to be plugged in while the truck isn’t in operation during colder months. This allows it to self-regulate, like the Nikola truck, for instance. It sort of wakes up once an hour to check the temperature and check the functions of the truck and make sure everything is sort of at a baseline that’s acceptable. And if not, it will try and heat up or cool down to that acceptable range.”

King said these mitigation strategies require the operator to allocate more time to their pre-trip activities, “which can put an impact not only on their hours but also the routes they’re traveling and the loads they’re carrying.”

A Slip Hazard

AMTA is concerned about operator safety, and the organizations research revealed one safety concern with FCEV operation in the winter months. King said it is related to where the truck vents, which is typically beneath the vehicle.

“In the summer months, we haven’t found this to be an issue,” she said. “However, in winter months, if a truck is idling in one spot for a considerable amount of time, the water will pool underneath the driver’s side where the truck is venting. If the truck is then shut off and nobody returns until the following morning, there’s often an icy patch that the third driver will have to watch out for in order to enter the truck.”

King added that because many FCEV OEMs manufacture their trucks in warmer climates, this has not been a top-of-mind consideration.

“We’ve advised our carriers participating in our winter trials to add this caution to their pre-trip checklist,” she said.

Planning the Route

Once the pre-trip inspection is completed and the truck is started and warmed up, King said there are other factors the operator must consider for a successful trip.

“Our trucks work harder in the extreme conditions to regulate and maintain a baseline to operate efficiently,” she said. “This means that hydrogen may be consumed at a rate almost 1.2 times faster than on a similar route with similar loads in summer months.”

While operators traveling the same route every day with similar loads can think they know when they need to refuel, operation during bitterly cold winter months means getting used to an all-new fueling cadence.

“Since fuel is not readily available, our drivers carefully and methodically plan their routes so they allow ample time and distance to reach the nearest fueling station,” King said. “When hydrogen is being consumed at a higher rate than usual, they need to make certain allowances so they can complete the designated routes, and they aren’t left stranded.”

Getting stranded in a hydrogen-fueled vehicle is a bit more serious than with a traditional diesel-fueled truck.

“We don’t have the ability to just bring a mobile fueler to the truck on the side of the road to provide hydrogen,” King said. “It’s not like running out of gas with your car, where you can just call an association, and they’ll bring you some gas. It’s critical that the drivers plan their routes so that they have adequate hydrogen to complete the journey and also account for the distance to the nearest fueling station.”

Regenerative Braking

On Alberta’s icy winter roads, regenerative braking in Class 8 hydrogen fuel cell trucks is a particular challenge for operators.

“Since this functions so differently from just applying the brakes in a conventional manner, drivers must be really attuned to the road conditions,” King said. “There isn’t the ability to do something like pump the brakes.”

She said that drivers need to adapt to the feel of the truck to ensure they use regenerative braking properly. This challenge is compounded by the automatic transmissions used in many of the fuel cell electric trucks.

“We had a lot of drivers provide feedback and complain that they can’t truly feel and drive the truck as they can with a standard transmission,” King said.

Driving downhill on icy roads is a particular challenge. King called it “a condition where a standard trend transmission would give them the ability to manipulate the truck favorably to respond to the road. They don’t have the ability to do that with regenerative braking.”

King said with practice drivers can get more comfortable with it and understand which level of regenerative braking they need to use.

While hydrogen does present some challenges in bitterly cold conditions, King said that the research AMTA is doing is valuable for OEMs.

“This is what trials are for,” she said. “We’re trying to identify the issues, identify those thresholds, and improve them. So, taking this valuable information back to companies like Nikola, they can work to improve those details. And getting the real-world testing — you just can’t beat that. You can’t get that information any other way.”

Challenges in fueling hydrogen trucks in extreme cold Canada’s Alberta Motor Transport Association reported on research it has done into fueling hydrogen-diesel dual-fuel trucks and FCEVs in bitterly cold conditions.