80% of global energy demand is currently met by fossil fuels like gasoline, diesel, jet fuel, kerosene, and bunker oil, which pump high amounts of carbon dioxide and other harmful pollutants into the atmosphere. Electrification and the build-out of zero-emissions electricity will play a critical role in decarbonization, but some important industries are difficult to electrify. Long-haul, heavy-duty trucking is one of them.
In the U.S., long-haul heavy-duty trucking accounts for nearly half of the nation’s on-road, carbon-emitting diesel fuel consumption and roughly 13% of U.S. transportation greenhouse gas emissions. Unfortunately, this type of trucking—like marine shipping and aviation—is an end-use case where vehicle weight and energy needs can make it hard to decarbonize with on-board batteries alone.
Zero-carbon fuels like low-emissions hydrogen, which contains no carbon and produces no carbon dioxide when combusted or used in a fuel cell, can play a valuable role in the decarbonization of hard-to-electrify systems, provided the hydrogen is produced in ways that minimize greenhouse gas emissions. For example, production facilities that make hydrogen by reforming natural gas need to be equipped with carbon capture systems, and the natural gas that’s used by those facilities must be sourced from systems that have taken all available steps to reduce methane emissions.
The ultimate cost of operating the hydrogen economy will also be important in determining its usefulness, and there are ongoing efforts to project the full range of costs associated with hydrogen fuel cell-powered trucks and how those costs compare to those of battery- and fossil fuel-powered systems. The research to date suggests very different results based on assumptions related to upstream factors like fuel production and transportation. In the case of long-haul trucking, however, a new, first-of-its-kind CATF report comparing the operational performance of hydrogen and battery electric powered trucks and identified several advantages to hydrogen fuel cell trucks and fueling infrastructure that could help to quickly and efficiently decarbonize that sector.
1. Heavy-duty hydrogen trucks stop fewer times and spend less time refueling overall
For context, the report simulated the performance of battery electric (BEV) and hydrogen fuel cell (FCEV) trucks and infrastructure as alternatives to diesel trucking on a popular long-haul route in the U.S. It was also assumed that the energy used to power the BEV and the FCEV has no or very low associated greenhouse gas emissions and that all vehicles were of a typical weight (an 80,000 lb Class 8 truck) for this type of trip.
One of the first advantages noted in this comparison is that the FCEV needed to make fewer stops than the BEV over the course of the trip. Because of its shorter range the BEV truck needed to make 8 total stops, during which significant portions of its battery (50 – 98%) needed to be charged. In comparison the FCEV required three stops, typically needing to refuel three-quarters of the tank, and the diesel drivetrain only needed one stop.
A second, and more critical advantage, is that the FCEV needed to spend less time refueling during the entirety of the trip. This fueling, or dwell time, was considerably longer for the BEV because each stop to recharge takes hours. Accounting for the state of charge at each stop and summing it over the entire route shows the BEV charging for 43 hours and 48 minutes. This is time when goods are not moving, something that may negatively affect delivery times and overall fleet operation. In contrast, the total fueling time for the FCEV is one hour and 24 minutes, approximately one hour longer than the diesel drivetrain.
2. Heavy-duty hydrogen trucks could have more room for cargo
Another key advantage of the FCEV truck is that it can carry more cargo. This is because the 1000 kWh battery required by the BEV could cause a 4,000–20,000-pound loss in cargo capacity. Lost cargo capacity has a demonstrable effect on fleet operations and in some cases can require the use of an additional BEV truck, compared to just one FCEV, to deliver all the goods.
To be clear, the FCEV truck also has a battery, but it is only 20 kWh and used for limited purposes (e.g., hill climbing, sudden acceleration, taking advantage of regenerative braking). That 20 kWh battery adds some weight, but only results in a few hundred-pound loss of cargo capacity relative to what can be carried on a diesel truck. Different FCEV designs may opt for a slightly larger battery, potentially up to 100 kWh, but since hydrogen functions as the main energy source, battery weight is not expected to become a major concern for FCEVs.
3. Fueling infrastructure for heavy-duty hydrogen trucks could be easier to build
The report also compared the needs of each truck types charging/fueling infrastructure along the same route by simulating 24-hour/day truck traffic along the same route, for two scenarios where either BEVs or FCEVs make up 100% of the trucks on the road. Overall, it was found that building out charging infrastructure for BEVs will likely require a larger number or much bigger stations to meet demand, mainly due to BEVs’ need to re-power more frequently and their longer dwell or charging time. Hydrogen infrastructure will also be challenging to build but has the comparative advantage of being more similar in size and number of stations, as well as operationally familiar as compared to diesel refueling technology, potentially making for fewer barriers to transition.
Is there a future for heavy-duty hydrogen trucks?
In summary, FCEVs were found to outperform BEVs in terms of the number of stops required (three vs. eight), total time spent refueling (1.4 hours vs. 43.8 hours), and available room for cargo (accounting for the weight of the powertrain). Additionally, while building charging and refueling infrastructure for BEVs and FCEVs could prove equally challenging, FCEV stations will have a smaller footprint and likely do not need to be as numerous, due to FCEV vehicle range and fast refueling times.
So, does that mean the future of the long-haul, heavy-duty trucking fleet is full of hydrogen trucks? Not necessarily. There are still a few things that need to happen before making that kind of change.
- We need funding for research and development to ensure hydrogen trucks are equally or more efficient to high-emitting diesel trucks. We also need more research and development to achieve fueling times equal to those of diesel as well as a reduction in drivetrain component weight to minimize potential cargo capacity limitations.
- We need to better understand how a transition would affect truck drivers’ and shipping operators’ bottom line. This report did not evaluate total cost of ownership for either alternative drivetrain, an analysis which would likely highlight other key hurdles, such as how the cost to produce, transport, and dispense hydrogen might adversely affect fleet operation expenses.
- We need to further build out the low-emission hydrogen economy and realize the full potential of zero-carbon fuels, including by:
- Developing connective infrastructure like dedicated hydrogen pipelines to anticipate expanding market demand to avoid supply bottlenecks;
- Commercializing the production of hydrogen as a zero-carbon fuel at scale, in the U.S. through measures like the Regional Clean Hydrogen Hubs program; and
- Developing hydrogen supply chains that minimize or eliminate emissions from production.
Battery electric trucks will likely play a significant role in the transition to zero-emission vehicles, but given the uncertainty over the future technology make-up of a decarbonized transportation sector, taking advantage of the merits of both BEV technology and hydrogen FCEVs is an important strategy for quickly and efficiently decarbonizing long-haul heavy-duty trucking.
Read the report, Zero Emission Long-Haul Heavy-Duty Trucking, for a detailed description of research methods and findings.