As the world is scaling up efforts to reduce our carbon emissions and a leading group of car OEM have committed to end fossil fuel powered cars, the trucking industry is under the spotlight, being both an essential backbone of the economy, one of the largest sources of emissions, and one of the most challenging use cases for decarbonization. While answers to such a complex problem are multiple and start with existing solutions – driving efficiency, loads consolidation, route optimization, and modal switch to rail – one question remains core and center to the industry: "Which technology holds the most promise to achieve zero emission trucking?"
Biofuels, the least disruptive solution but probably not scalable
Biofuels are already significantly used and have the advantage of being compatible with the existing fleet with some retrofit. Today's biogas production amounts to 35 Mtoe, and the total estimated potential based on waste only could reach 600 to 700 Mtoe, according to the International Energy Agency, would barely cover global trucking industry needs. Questions remain on how much of that potential would be economically viable and in the short term, they should be developed and used to their maximum potential, but in the long run, they may be prioritized for shipping and aviation rather than trucking.
Battery Electric Trucks (BET) or Hydrogen Fuel Cells (HFC), a debate requiring a more systemic approach
While there is little debate about biofuels, most of the industry is indeed looking at whether their future will rely on batteries or hydrogen. Proponents of each technology highlight the better payload (1,5T), longer range (up to 1200 km), and faster refueling (10 to 15 min) of HFC, while BET shows an energy consumption three times lower and lower Capex and maintenance costs. Besides the respective advantages of each technology to support trucking, their impact has to be considered more widely through a systemic approach as trucks will ultimately need CO2-free electricity to be moved and the transition out of ICE, a whole new supply chain and infrastructure.
Electric Vehicles: a fast adoption for passenger cars thanks to supercharging
Before focusing on trucks, let’s look at passenger cars. It seems like the game is over, and BEV (Battery-Electric Vehicles) have not only taken over HFC (Hydrogen Fuel Cell) but are also planned to replace ICE (Internal Combustion Engines) in the next couple of decades as increasing economies of scale progressively replace subsidies.
Looking back at that transformation, it is remarkable to notice that the roadblock to massive adoption was more easily removed by developing fast charging than ever again increasing the battery range, which would deteriorate competitiveness and environmental impact.
Hydrogen would require 3 times more CO2 free electricity, a resource that is still far from abundance
The first thing to consider is the impact on electricity production as batteries or hydrogen, both will need CO2 free electricity. Looking at the current situation, global renewable electricity amounts to 7 600 TWh, including nuclear, would equal 10 300 TWh of non fossil fuels and low carbon or 38% of total electricity. In comparison, at current efficiency levels, converting 100% of trucking to BET would require 3500 TWh, while going to HFC would require 10 000 TWh. These primary constraints and the considerable Capex and significant time needed to grow CO2-free electricity production indicate that BET should be prioritized.
Hydrogen and Batteries: both technologies will require huge resources…
Secondly, we must look at the supply chain required to support this transition. BET will require vast amounts of minerals (mostly Lithium) and battery production, while HFC will require a significant scale-up of hydrogen electrolysis (today’s hydrogen production is 95% out of fossil fuels, only 5% out of electrolysis). In both cases, we are talking about multiplying current production levels by a few dozen times but the current and planned ramp up show a significant advantage to batteries given the momentum initiated with passenger cars. As minerals are a finite resource, we also need to consider Lithium resources, and with 86 Mt of Lithium, we have several times what would be needed to cover the global fleet of cars and trucks, notwithstanding the need to reduce global fleet and scale up recycling to close the loop.
… and will face competing usages
Besides supply chain ramp up, competition for usage can also be a roadblock to new technology adoption. In the case of batteries, cars are a decade ahead and taking the lion’s share of the Lithium battery production. On the other hand, trucks should be prioritized as they can generate 3 to 4 times more CO2 reduction per kWh of battery than a car. An average car runs mostly short distances daily but still gets a 500 km range battery for longer trips when the average distance of a truck is anywhere between 200 and 700 km but with a more regular pattern allowing better utilization of the battery.
In the case of HFC, no one expects passenger cars to be a competition for clean hydrogen from electrolysis. However, there are numerous usages, including existing ones (chemistry, metallurgy, cement) currently supplied by hydrogen from fossil fuel or new ones to be developed (grid injection, synthetic fuels for shipping or aviation…)
Batteries technology is more mature and progressing faster…
Another dimension to consider is technological maturity. Lithium batteries have greatly benefited from mobile devices to become competitive for passenger cars, and they keep progressing. While they are already available for trucking and could also become cost competitive in the next few years, HFCs have been around for many decades, have shown much slower technological progress, and mass production is not expected before the decade's end.
… and would require a slightly less expensive infrastructure
Lastly, both BET charging and HFC refueling will require an entirely new infrastructure. Estimates are that BET would need 30 times more chargers than hydrogen refueling stations (especially considering that 90% of chargers would be overnight slow charging), but on the other hand, that charging infrastructure cost would end up 30% higher for HFC than for BET.
Considering economic competitiveness and CO2 reduction, BET energy efficiency can’t be matched…
With energy (fuel today, electricity tomorrow) representing 20 to 40% of the cost structure of trucking, the balance also leans strongly in favor of BET (remember BET requires three times less electricity than HFC) unless vast amounts of cheap CO2 free electricity would be available to be converted in hydrogen but not available for battery charging. Even considering lifecycle emissions related to battery manufacturing, BET achieves a better carbon footprint than HFC with comparable electricity sources.
What about payload, a clear advantage for HFC so far but does it matter that much?
While the current advantage for HFC is significant (for heavy-duty trucks, HFC would be 1,5 T heavier than ICE when BET with a 500 km range would be 3 T heavier), it should be put in perspective of the max payload 24 T, the fact that both BET and HFC enjoy a 2 T payload allowance in many countries but also the fact that the vast majority of full truckloads are rather saturated by volume rather than weight. Last but not least, as BET technology matures, the switch to a fully electric powertrain with smaller motors on each axle could allow for bridging that gap by removing the weight of the transmission. We can also expect further progress in battery energy density or similar to what is happening with passenger cars. The battery pack becomes part of the structure, both evolutions resulting in additional weight savings.
Range and refueling: the most challenging part for BET
In an industry with thin margins, who would accept significant productivity losses especially when labor is the second, if not first, a portion of the cost base? In this case, it is also good to remember that the vast majority of the global trucking fleet is performing daily distances that are compatible with current battery ranges (400 km and soon 500 km) and overnight charging at facilities. Nevertheless, the vast majority of emissions are produced by a smaller number of heavy-duty trucks covering longer distances, and in this case, the competition between HFC and BET could be tighter.
One should, however, also consider the current trend of progress with MW charging capabilities that could reduce recharging down to what passenger cars can already experience today, 20 to 30 min to get back 80% of the range, a timing which ends up well aligned with most safety regulations requiring mandatory breaks from drivers. Last, options like battery swaps or catenary systems could contribute to range extension.
So all in all, if the systemic analysis (electricity availability and energy efficiency, required supply chain and infrastructure, technological maturity) as well as desired benefits (economic competitiveness, CO2 reduction) all play in favor of BET, if payload is not really a game changer, then maybe the industry should rather work on answering the question:
"Do we really need trucks with more than 1 000 km range and 10 min refueling time?"