Hydrogen Fuel Cells vs Battery Electric Trucks: The Payload Tax

Freight decarbonisation is usually argued as an infrastructure question: where do the chargers go, where does the hydrogen come from, who pays for the pipeline. Those are real questions, but they are downstream of a simpler one that a fleet operator asks first. How much of my payload does the powertrain eat?

That question is not rhetorical. A tractor-trailer in Europe is limited to 40 tonnes gross, and the cargo is whatever is left after the tractor, the trailer, the fuel system and the driver. Every kilogram of fuel system is a kilogram of cargo that does not get paid for, and freight economics are unforgiving about that.

Part One: The battery weight problem, quantified

A long-haul tractor needs roughly 500 to 800 kilometres of range to fit into a normal duty cycle with one mandated break. At a consumption of about 1.1 kilowatt-hours per kilometre for a 40-tonne combination, 800 kilometres requires roughly 900 kilowatt-hours of usable energy.

Current production cells run at 250 to 300 watt-hours per kilogram at the pack level, once cooling, casing and management electronics are counted. At 280 Wh/kg, 900 kWh is about 3.2 tonnes of pack. Add the structural reinforcement the chassis needs to carry it, and the practical figure is 3.5 to 4 tonnes.

A diesel tractor carries about 700 kilograms of fuel and tank for a comparable range. So a battery-electric long-haul tractor gives up roughly three tonnes of payload, which at European freight rates of 100 to 150 euros per tonne per long trip is the difference between a profitable route and a marginal one.

This is not an argument against battery trucks. It is an argument about which routes they serve. A regional truck doing 300 kilometres a day needs 350 kWh, which is 1.3 tonnes of pack, and the payload penalty is small enough that the lower energy cost wins. The problem is specifically the long-haul, high-payload segment.

Part Two: The hydrogen weight problem, quantified

Hydrogen looks like it solves this, and in one sense it does. A fuel cell system for a 40-tonne truck is roughly 1 to 1.5 tonnes including the stack, the balance of plant and the smaller buffer battery. A 700-bar tank system holding 40 kilograms of hydrogen weighs about 1.5 to 2 tonnes, because a pressure vessel is a heavy object.

Total: about 3 tonnes of powertrain and storage, for 700 to 800 kilometres of range. That is the same order as the battery. The payload advantage that the hydrogen lobby advertises is real at 350 bar and short range, and largely disappears at 700 bar and long range, because the tank is the heavy part and the energy density of the fuel does not help if you cannot store it cheaply.

Where hydrogen does win on weight is at very long range and high duty cycles, where the marginal cost of more range is another tank rather than another tonne of cells. That is a narrower window than the marketing suggests, and it is exactly the window that mining haul trucks and long-distance coaches occupy.

Part Three: The energy chain, honestly

The efficiency argument is well known and still worth stating precisely. A battery-electric truck converts about 85 to 90% of grid electricity into motion, counting charging losses and drivetrain. A hydrogen truck converts about 60 to 65% of the hydrogen's energy into motion at the fuel cell and motor, and producing that hydrogen from electrolysis costs another 60 to 70% of the input electricity. The round trip is roughly 35 to 40% efficient, against 85 to 90%.

That means a hydrogen truck needs two to two and a half times the renewable electricity of a battery truck for the same distance. If electricity is the constrained resource, which in most grids it is, that is the decisive number. If hydrogen is available as an industrial by-product at a low price, which in a few clusters it is, the calculation changes.

The cost of green hydrogen is currently quoted at 5 to 9 dollars per kilogram in most markets, against a diesel-equivalent energy cost that would require roughly 3 to 4 dollars per kilogram to compete without subsidy. That gap is closing, slowly, and it closes fastest where electricity is cheapest and electrolyser utilisation is highest.

Part Four: The infrastructure asymmetry

A battery truck charges at a depot. The depot is a known location with a known grid connection, and the upgrade cost is a one-time capital item that the fleet can amortise. A hydrogen truck refuels at a station that must exist on the route, which means somebody has to build a network before the trucks arrive, which means somebody has to take demand risk.

That chicken-and-egg problem is the reason hydrogen truck deployments have clustered around corridors with captive fleets: a port, a mine, a supermarket distribution network with fixed routes. Inside a closed loop, the station can be sized to the fleet and the demand risk is under the fleet's own control. On the open road, the risk is borne by whoever builds first, and nobody wants to be first.

Battery charging has the mirror-image problem at a different scale: a depot full of trucks charging at once is a multi-megawatt load, and the grid connection may take longer to obtain than the trucks take to deliver. That is why depot charging is increasingly paired with on-site storage and a demand-limited contract, which is a battery business wearing an infrastructure hat.

Part Five: What this means for the people who drive and the towns that host

The social consequence of this choice is not usually discussed in powertrain terms, but it is large. Battery trucks favour depot-centric operations, which favours large fleets with their own yards. Hydrogen favours corridor operations, which favours whoever owns the corridor.

If battery wins, the freight industry consolidates around operators who can afford megawatt depots and the grid upgrades behind them. If hydrogen wins, it consolidates around whoever builds the fuelling network, which historically has meant energy majors. Either way, the small haulier with ten trucks and a rented yard is the party that struggles, and that is a labour and regional policy question as much as a technology one.

Market sizing

The global truck market is roughly 3 million heavy-duty units a year. Battery-electric and fuel-cell trucks together are still under 2% of that, with the zero-emission share concentrated in China. Forecasts for 2030 range from 10 to 25% depending on the region and on whether the forecast assumes a carbon price. The hydrogen share of that zero-emission fleet is the number to watch: it has been revised downward every year for four years, from a majority to a minority, and the payload arithmetic is the reason.

The comparison that matters

Battery-electric optimises for energy efficiency and depot simplicity, and pays in payload on long routes. Hydrogen optimises for range and refuelling time, and pays in energy efficiency and infrastructure risk. The route decides which cost you pay, and most routes are shorter than the marketing assumes.

The practical rule for a fleet: count the tonnes of payload you lose, multiply by the freight rate on your actual lanes, and compare that to the energy cost difference over five years. The answer will be different for every fleet, which is exactly why a single national strategy for either technology is likely to be wrong for half the industry.

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