H2 vs. Electric Heavy Duty Trucks
“If you bought it, a truck brought it.” That’s the unofficial motto of the trucking industry, although apparently there’s actually a 73.7% chance a truck brought it, as the Department of Transportation estimates trucks moved $10 trillion of the country’s $13.6 trillion in freight in 2012. Unfortunately, the freight industry’s economic contribution comes with similarly sized carbon emissions.
According to the U.S. National Blueprint for Transportation Decarbonization released in early 2023, “While MHDVs represent only 5% of total vehicles on the road, they are responsible for an outsized 21% of transportation emissions, making them the second-largest emissions contributor behind only light-duty vehicles. And within MHDVs, a small portion — about 10% of heavy trucks with high utilization — is responsible for approximately 50% of total MHDV emissions.”
To address the 7% of emissions attributable to long-haul heavy trucks (see below), the U.S. government expects to deploy some electric trucks, but primarily those powered by hydrogen and sustainable liquid fuels.
Is this actually a reasonable strategy? Someone recently asked me what the $/tonne CO2 abatement costs were for electric vs. hydrogen trucks, which sounded like an interesting question to investigate. While I don’t know how academics perform their sophisticated calculations, we can certainly do some back-of-napkin math. So here goes…
The simple approach: fuel only
The naive model considers only fuel costs and emissions. We’ll start by calculating how much diesel would have to be displaced to remove 1 tonne of CO2, then calculate the costs of traveling the equivalent distance on hydrogen and electricity. Diesel generates 10.180 × 10^-3 tonnes of CO2/gallon of diesel, which means it takes 98 gallons of diesel to generate 1 tonne of CO2. At today’s federally mandated fuel efficiency of 7.2 mpg, this enables a truck to travel 705 miles. If we assume $3.50/gallon of diesel, traveling this distance costs $343.
What is the cost of hydrogen to travel the same distance? According to the ICCT, hydrogen trucks travel about 7 miles/kg of H2. Therefore, a truck would require ~100 kg of H2 to travel 705 miles. If we use $8/kg of H2 (lower end of today’s prices), this means it costs $800 to go the distance. If we assume the $5/kg of H2 the ICCT projects we can achieve around 2025, it will cost $500.
What about electric? The Tesla Semi can achieve 1.7 kWh/mi, or 0.59 mi/kWh today. If we’re a bit conservative and round down to 0.5 mi/kWh, that means it will take 1410kWh to travel 705 miles. Let’s assume electricity costs $0.20/kWh. That means it costs $282 to go the distance. (Tesla claims $70k annual fuel savings and a 2-yr payback, but this seems to be based on very optimistic electricity prices of <$0.10/kWh, so we won’t take that seriously here.)
What does this mean? Per tonne of CO2 offset,
- Hydrogen trucks would incur a cost of $800-$343 = $457/tonne at today’s prices, or $500-343 = $157/tonne assuming future $5/kg H2 costs.
- Electric trucks, on the other hand, would cost $282-$343 = -$61/tonne — in other words, it actually saves money!
(Slightly) more sophisticated: lifetime vehicle costs
But we also have to consider upfront vehicle costs….to compare this accurately, let’s look at lifetime cost.
A typical semi truck can last 750k miles or more. This means it will take 104,000 gallons of diesel ($365,000), 106,000 kg of H2 ($851,000 today or $532,000 future), or 1,500,000 kWh ($300,000), generating 1064 tonnes of CO2 in the process.
Princeton’s Net Zero America Project report (pages 54–55) expects that by 2030, electric heavy duty trucks will cost $118k more, and hydrogen trucks will cost $34k more, than the diesel equivalent.
Therefore, the total cost delta over the lifetime of a vehicle considering both upfront and fuel costs are:
- Hydrogen: $851,000-$365,000 (fuel) + $34,000 (upfront) = $520,000 ($8/kg H2) or $532,000-$365,000 (fuel) + $34,000 (upfront) = $201,000 ($5/kg)
- Electric: $300,000-$365,000 (fuel) + $118,000 (upfront) = $53,000
Dividing by the amount of CO2 removed, abatement costs are therefore:
- Hydrogen: $520,000/1064 tonnes = 489/tonne (today) or $201,000/1064 tonnes = $189/tonne (future)
- Electric: $53,000/1064 tonnes = $50/tonne
Conclusion
Clearly, it seems like electric heavy duty trucks are the winner here. Of course, the reality is not binary — we’ll likely have predominantly electric heavy trucks, supplemented by hydrogen trucks for loads that are too heavy or far for batteries. It would seem like others agree — the North American Council for Freight Efficiency (NACFE) expects that a 500-mile range battery electric truck could be viable for at least 50% of 53 ft trailer loads, because most loads aren’t constrained by weight. Princeton’s Net Zero America Project expects that electric heavy duty trucks will comprise ~60% of sales, with the remainder served by hydrogen powertrains.
A brief postscript
Some of you might be wondering, “But what about infrastructure costs? Wouldn’t hydrogen require fewer refueling stations than electric chargers?” Let’s take a look at this.
If we’re extremely optimistic, we can use the H2 industry’s estimate of 10 minutes to refuel (today this time is closer to 30 minutes, which isn’t much different from EV charging). Assuming an additional 10 minutes per fueling session to account for ingress/egress delays and underutilization, a station could serve 72 trucks per day. The cost for a H2 refueling station averages $1.9M according to the DOE.
For electric heavy trucks, let’s assume they need to charge 2x per day, and a charge session takes 45 min. Adding the same 10 minutes for delays and underutilization, each station could serve 14.4 trucks per day. Based on experience, we expect the cost for installing a 500kW DC fast charger to total $375,000.
Therefore, comparable infrastructure costs are:
- Hydrogen: $1.9M per station / 72 trucks per station = $26,389/truck
- Electric: $375,000 per station / 14.4 trucks per station = $26,042/truck
It appears that there’s not much difference in infrastructure costs, and this is before considering the additional complexities involved in building a hydrogen distribution system vs. our existing electrical grid. Of course, building out a capable freight charging network will still be a heavy lift, so let’s get started!
