This article will concentrate on what fuel-cell electric vehicle (FCEV) alternatives have to offer. What can one expect and what are the unknowns? To prepare, we spent time with Accelera™ by Cummins team members who shared with us the technical aspects of FCEV, but moreover, where they see it being applied in the future.
FOLLOWING PROMISING PATHS FORWARD
Customers will have a choice of power in the future. One path to decarbonization is the traditional ICE and the other is an alternative, zero-emissions form of power.
The customer’s choice leads to a series of decisions. What is the product? What is the channel of distribution? What is the promotion, etc.? ACT has been providing answers and direction about what power will be available in the future and what might be the right choice for your particular operation.
Much of the information needed to make that choice is not currently clearly in sight, just over the horizon. One path toward decarbonization reduces the emissions from ICE, while the other eliminates combustion and emissions created through the combustion process. Each path has associated costs, required changes in daily operations, probability of successful adoption, and time required for success. Being an early adopter is no guarantee of success, but being late in the decision-making process can have dire consequences.
We know much more about the ICE path. Diesel engines are cleaner than ever and will be even cleaner with the new diesel emission standards. Cleaner NG is already available with higher horsepower versions soon to arrive. Renewable NG (RNG) is another promising path to zero-emissions fuel. Truck chassis really won’t change much with the adoption of these cleaner alternatives. The engine is in the front of the vehicle, followed by the clutch, transmission, and rear axle. The fuel tanks may be different, but overall, the vehicle is pretty much the same. The zero-emissions path will have fuel cells, hydrogen tanks, electric drives, and a host of other changes that are not conventional. What ACT has attempted to do with this “Alternative to Diesel” series is provide insight to give you a competitive advantage as you contemplate these changes to your operations.
Where does ACT get its information? ACT has a special connection with transportation industry leaders, from OEMs to major suppliers to fleets and leasing organizations of all kinds. One of those relationships is with Cummins and Accelera, particularly their engineering and support staff, with whom we’ve been able to discuss these new technologies, get answers to our technical questions, and gather information our readers need to know to help them make immediate and future business decisions about alternative power. One of the reasons we spoke with Accelera is their “big picture” and agnostic view of many technologies.
On one hand, Cummins continues to work on traditional ICE alternatives with new offerings of NG and hydrogen-fueled engines. Cummins has covered the other path with the announcement of its fifth operating segment, Accelera, which provides zero-emissions technologies such as battery-electric and fuel cell-electric powertrain solutions, along with electrolyzers for green hydrogen production. For Cummins, Accelera is a key part of their “Destination Zero” strategy. The strategy is rooted in the understanding that multiple solutions are required to achieve industry-wide decarbonization across diverse applications. The company has no illusions that the change in fuels will be a light-switch event, but rather a destination with early adopters, a messy middle, and a wide variance by countries and global regions.
So, what is a hydrogen FCEV? FCEVs use a propulsion system like that of battery-electric vehicles (BEVs), where energy stored as hydrogen is converted to electricity by the fuel cell capable of providing direct electricity to the electric motor(s) while in operation. Basically, it is a BEV that has a combined H2 fuel tank and fuel cell engine that converts H2 and oxygen to produce electricity and water. It is able to keep the battery charged and provide direct electricity for the traction system. The FCEV uses the same components as a BEV but adds the fuel cell and H2 fuel tank. The hydrogen is stored on board in high pressure tanks much like a NG-fueled truck. You can review the basics of H2 ICE and BEV by clicking HERE.
FCEVs can travel the highways just as any diesel, NG, or H2-fueled ICE-powered truck can. The FCEV can refuel at any truck stop offering hydrogen fuel or a behind-the-fence operation just as an ICE-powered vehicle would. There is one BIG difference in the operation of the two types of vehicles, and it is why the FCEV shows so much promise. The basic difference is that there is no combustion with the FCEV, and thus, no emissions. Let that sink in for a minute. No matter what we do with diesel fuel, NG, H2, or any other fuel that is burned in a combustion chamber, while low, we still get emissions. Yes, we use particulate traps, three-way catalysts, diesel exhaust fluid (DEF), and who knows what else when we get to the 2027 emission standards, but in each case we must deal with the byproducts of combustion. With a hydrogen fuel cell, the energy we need comes from a chemical reaction and not combustion, so there is nothing from the tailpipe except water vapor. The hydrogen fuel cell generates the electricity to the electric motor(s) propelling the truck and the cargo down the road. The basic design is simple, but the execution is complex.
The execution of the design is the “science of compromise.” We have many options for putting a FCEV together, and along the way, we must make compromises. Will the electric motor(s) be mounted at one or more of the drive wheels, or will we use a driveshaft from an electric motor to a conventional rear axle design? Where will we place the primary electric battery? How big does it need to be in terms of power output? How heavy a load are we going to be pulling? What is the maximum grade we will need to pull and at what minimum speed? After we make those decisions, we will have a better idea of how big our fuel cell needs to be in terms of power output to provide the electric power to the vehicle. Then we’ll need to decide how far we want the vehicle to go before we need to refuel. Since the hydrogen fuel needs more volume than weight, our hydrogen fuel tanks will take up more room on the vehicle, as well as weight, than conventional diesel fuel tanks to go the same distance. When all of the above decisions have been made, we can figure out how we will get all of the components into the basic vehicle as we know it today.
With a pure BEV, the battery is sized to match the vehicle’s duty cycle. FCEVs are designed to be capable of providing primary power to the electric motor(s) to achieve vehicle duty cycle performance requirements, while additional battery electric power can be used to help manage through transients or to create the most optimal TCO solution based on application requirements. The whole process is similar to spec’ing a diesel truck. How much power do we need and how much diesel fuel are we going to have in the tanks? In general, we can use a smaller sized battery than in a BEV, because we have the hydrogen fuel cell to provide the extra mileage “energy” that we need.
As with the BEV, the noise of a hydrogen-fueled vehicle is different than that of an ICE vehicle. You will hear the noise of some pumps, switches making contact, etc., but not the sound of combustion taking place. Again, as with a BEV, a separate electrical system will be used for the vehicle lights, A/C and heating systems, and other electrical systems just as on an ICE vehicle. Why redesign all the electrical components on a conventional ICE truck to match a high voltage battery when a simple 12-volt system will do?
The engineer’s goal is to make refueling time equal to diesel, and they are making progress. Any current gap in refueling times should be considered a temporary gap. Remember, besides the diesel fuel, we may need to refuel the DEF tank, which takes additional time. It will take incremental time to fill the hydrogen tanks, like what happens today with the NG refueling process.
A typical FCEV will weigh more than a comparable spec’d diesel-fueled tractor. However, the maximum payload of a typical FCEV tractor-trailer will be in a neighborhood comparable to diesel. This is not a show stopper, as 70% of the tractor-trailers on the road today “cube out” (the trailer is full and no more freight can be loaded) as opposed to 30% of units that “gross out” (the combined weight of the tractor-trailer is at the maximum legal weight). FCEV will receive a weight exemption, much like that of a NG-powered unit, which in some states gets an extra 2,000 pounds, so the FCEV would be competitive with a traditional diesel-fueled tractor. What happens in those states where ICE-powered tractors are banned? It won’t make any difference whether you “cube out” or “gross out,” you will need to consider alternative power.
Maintenance will be a little different for a FCEV than for a typical diesel tractor. Some things will stay the same, such as tire and brake changes. Clutch and transmission rebuild and adjustments will be a thing of the past, as will work on DEF systems, catalysts, and particulate filters. Some operations will be completely new, such as electric drive motor maintenance and repair/rebuild. Basically, FCEV maintenance will be the same as that for a BEV, with the addition of the hydrogen fuel cell. There may be a requirement for fire suppression equipment because of the nature of hydrogen, but many shops that have run NG-fueled equipment already have experience.
The fuel cell will mix the hydrogen with oxygen in the air to get the electrical power we need, as well as a little heat and a little water vapor. The air must be clean…really clean…so as not to get any impurities into the polymer electrolyte membrane (PEM) where the chemical process takes place. The PEM is a very thin solid organic compound, about as thin as a couple sheets of paper, where the ion exchange takes place. The membrane must be kept moist for particles to pass through it. This article won’t delve deep into the physics of how a fuel cell works, except to say that the process is well understood and used in many applications.
A fuel cell engine has similarities to a diesel engine as they both have fuel systems, air handling systems, thermal management systems, and control systems. While a diesel engine has combustion, a fuel cell has a stack comprised of many cells executing the electrochemical process of converting hydrogen fuel to electricity. The size of the stack correlates to the electrical power output. The individual fuel cells are combined into a series of fuel cells called a “stack” to get a higher voltage power unit than an individual cell. So, the “stack” may consist of hundreds of individual fuel cells to get a much higher voltage, sizing it to meet driver demand and heavy-duty commercial application power requirements.
As with anything new, there are several hurdles that require a change in thinking. As such, some may say FCEV will never be accepted. Here are several common topics of debate, with both perspectives, for FCEVs:
There aren’t many refueling stations today. The full infrastructure won’t appear overnight, but with dedicated routes, or routes with appropriate mileage constraints, the ecosystem could be developed for range viability. If hydrogen, particularly clean hydrogen (not made from fossil fuels), is developed for other purposes, the “ecosystem” can develop that much faster for trucks. Remember how quickly DEF became available at the diesel pumps.
Trucks will need larger fuel tanks than traditional diesel! Yes, they will; hydrogen has lower volumetric energy density than diesel. Thus, you need more on board, meaning more space consuming high-pressure tanks. The problem was overcome with natural gas, and hydrogen will follow a similar model.
With the instant torque the electric motor(s) provide, tire wear can be a real problem! Tire costs per mile will be out of sight. The development engineers are on top of this problem, with the ability to control or limit the amount of power the electric motor(s) can provide at launch. The amount of power can be controlled. The logic of traction control is well understood. Thus, a BEV or FCEV can be programed to have the same acceleration characteristics as today’s diesel trucks.
Won’t the operational costs for a hydrogen FCEV be higher than diesel? Perhaps, but with no combustion, there are no emissions except water vapor. With increased volumes, hydrogen FCEV costs will decrease. Diesel starts today with a cost advantage, but it faces significant cost hurdles in the future. Typically, a kg of hydrogen is compared to a gallon of diesel fuel. We could see fuel parity in the 2030s as the supply chain matures.
Won’t FCEV life cycle cost be more? Initially yes, but there are some things to consider. A FCEV can replace the battery when their useful life in a truck is done, but they can still have value in a secondary market, such as for backup power for communities in case of emergencies. For diesel engines, what do you do with the engine or the truck when emissions must be maintained for a much longer period of time, as is being discussed with the new 2027 truck emission laws? How big will the diesel-powered used truck market be if there are some first owner and second owner emission requirements with associated costs? In the past, trucking companies have been able to pass new costs to consumers. Let us assume they will be able to do so in the future.
It doesn’t have a Jake Brake option, so how do I slow the vehicle down and save on brake wear? No, it doesn’t have a Jake Brake, but it has regenerative braking that charges the battery and slows the vehicle down. The FCEV has the ability to “kinetically run” the electric motors in “generator mode” to charge the batteries and slow the vehicle by applying a retarding torque. The electric motors can generate electricity saving on hydrogen fuel.
Where do we get the hydrogen fuel? The beauty of hydrogen fuel is that it can be generated from wind and solar sources, which is known as clean (or green) hydrogen. The green hydrogen fuel is created from electrolyzers where the electricity is created from these renewables. As mentioned previously, they are coming into use not just for trucks but for other purposes. Some generate hydrogen fuel from natural gas, others from other petroleum sources.
How does ACT view the future of powertrain alternatives?
While ACT remains fuel agnostic, and believes fleets know their operations better than anyone else, we also recognize ICE costs will rise as increased emissions regulations are globally adopted, and tougher regulatory standards for ICE will lead to a more favorable TCO for CEV. Most CVs are working in competitive situations, so questions on operating costs are fundamental. Will each powertrain alternative — EV, FCEV, H2 ICE, etc. — offer varying degrees of ROI? Yes. And, of course, this depends on each application’s unique duty cycle. ACT Research uses a bottom-up approach, analyzing component costs, operational costs based on duty cycles, fuel costs, maintenance costs, taxes, infrastructure, and more.
In June 2023, our team published the third edition of CHARGING FORWARD, featuring additional powertrain analysis to our current battery and fuel cell electric to include natural gas, hydrogen, H2 ICE, gasoline, propane, and hybrid powertrain alternatives, forecasting the adoption rates of 52 vehicle applications across Classes 4–8 CVs in North America, Europe, and China. We’ve created this model to provide guidance for strategic business planning over the next 15 years, so your business is strongly positioned for a decarbonized future.