Hydrogen Combustion Engines (H2-ICE) 2026: JCB & Toyota Heavy Duty Strategy

Executive Summary

While most hydrogen headlines focus on fuel cell trucks, a parallel movement led by companies like JCB and Toyota is betting on hydrogen combustion engines (H2-ICE) for heavy-duty applications. The pitch is simple: reuse the industrial and manufacturing base of diesel engines, swap fossil fuel for hydrogen, and achieve deep CO₂ reductions with familiar hardware and maintenance routines. The reality is subtler: H2-ICE offers lower efficiency than fuel cells and faces NO_x and infrastructure challenges, but could carve out significant niches where robustness, low capex, and fast refuelling trump peak efficiency. At Energy Solutions Intelligence, we benchmark H2-ICE versus fuel cells and diesel in construction, agriculture, and heavy trucking.

• Modern H2-ICE concepts can deliver well-to-wheel CO₂ reductions of 70–90% when fuelled by green hydrogen, but real-world performance depends on engine calibration, aftertreatment, and upstream H₂ production.
• Indicative tank-to-wheel efficiency for H2-ICE heavy-duty engines is roughly 30–40%, compared with 45–55% for fuel cell systems and ~40–45% for high-efficiency diesel engines.
• Capex per vehicle for H2-ICE is typically lower than for fuel cell trucks, particularly where OEMs can adapt existing engine platforms, but hydrogen storage and refuelling infrastructure costs remain significant.
• NO_x emissions must be managed with advanced combustion strategies and aftertreatment, especially for lean-burn engines; regulatory compliance is a key design driver.
• Early deployments by JCB (off-road equipment) and Toyota (heavy trucks) suggest H2-ICE will target specific duty cycles and markets rather than displacing fuel cells across the board.

What You'll Learn

• H2-ICE Basics: Combustion Concepts, Architectures, and Fuel Storage
• Benchmarks: Efficiency, Power Density, and Emissions vs Diesel and Fuel Cells
• JCB & Toyota Strategies: Off-Road Machines and Heavy Trucks
• Economic Analysis: TCO vs Diesel and Fuel Cell Alternatives
• Hydrogen Supply & Refuelling: Pressures, Throughput, and Depot Design
• Where H2-ICE Makes Sense: Duty Cycles, Regions, and Sectors
• Outlook to 2030/2035: Market Share Scenarios and Policy Signals
• FAQ: Hydrogen Combustion Engines, NOx, and Investment Decisions

H2-ICE Basics: Combustion Concepts, Architectures, and Fuel Storage

Hydrogen combustion engines replace diesel or gasoline with hydrogen while retaining much of the existing engine block, crankshaft, and drivetrain architecture. Combustion concepts include lean-burn and stoichiometric operation, with hydrogen introduced via port injection or direct injection.

Key architectural choices include:

• Port fuel injection (PFI): Hydrogen injected into the intake manifold; simpler hardware but higher risk of pre-ignition and lower efficiency for some duty cycles.
• Direct injection (DI): Hydrogen injected directly into the cylinder; better control of combustion and knock, but more complex injectors and control strategies.
• Lean-burn vs stoichiometric: Lean-burn can improve efficiency and reduce fuel use, but requires more complex NO_x control, while stoichiometric operation enables three-way catalysts but at the cost of higher hydrogen consumption.

Benchmarks: Efficiency, Power Density, and Emissions vs Diesel and Fuel Cells

Heavy-duty operators care about power density, efficiency, and emissions. The table below summarises stylised benchmarks for a 350–450 kW powertrain used in trucks or large off-road machines.

JCB & Toyota Strategies: Off-Road Machines and Heavy Trucks

Case Studies: JCB Hydrogen Engines and Toyota H2-ICE Trucks

Case Study 1 – JCB Hydrogen Combustion Engines for Construction Equipment

Context

• Segment: Construction and agricultural machinery (loaders, excavators, telehandlers).
• Strategy: Retrofit diesel engine platforms to burn hydrogen with minimal changes to the rest of the machine.
• Motivation: Preserve existing supply chains and mechanic skills, while reducing CO₂ and tailpipe pollutants.

Technical Features (Indicative)

• Hydrogen storage via high-pressure tanks (e.g. 350 bar) integrated into the chassis.
• Optimised combustion and ignition systems to manage knock and NO_x.
• Emissions control using aftertreatment adapted from diesel platforms.

Case Study 2 – Toyota’s Hydrogen Combustion Trucks

Context

• Segment: Heavy-duty trucks in Japan and selected international markets.
• Strategy: Parallel development of fuel cell trucks and H2-ICE prototypes, leveraging existing engine plants.
• Motivation: Provide multiple hydrogen pathways to customers depending on route structure and infrastructure.

Insights

• H2-ICE trucks can offer high peak power and robust transient response, important for certain freight duty cycles.
• Total cost of ownership depends strongly on hydrogen price, utilisation, and maintenance intervals compared with FCEV alternatives.

Economic Analysis: TCO vs Diesel and Fuel Cell Alternatives

Total cost of ownership (TCO) for hydrogen options involves trade-offs between capex, fuel cost, maintenance, and residual value. H2-ICE tends to win on capex and familiarity, while fuel cells win on efficiency when hydrogen is expensive.

Hydrogen Supply & Refuelling: Pressures, Throughput, and Depot Design

For fleet operators, the choice between H2-ICE and fuel cells is inseparable from hydrogen refuelling strategy. Both require robust hydrogen logistics, but H2-ICE may tolerate slightly lower purity requirements and can benefit from shared infrastructure with other industrial uses.

Where H2-ICE Makes Sense: Duty Cycles, Regions, and Sectors

H2-ICE is unlikely to dominate all heavy-duty segments, but it can fill important niches where robustness, cost, and existing engine expertise are highly valued:

• Construction and agriculture: Machines operating close to central depots, where hybridisation and fuel cells may be less attractive due to dust, vibration, and operator familiarity.
• Regional trucking: Routes with predictable distances and access to hydrogen hubs, where H2-ICE can provide a bridge until fuel cell costs fall further.
• Markets with strong ICE supply chains: Regions where local content and job preservation arguments support ICE-based hydrogen options.

Outlook to 2030/2035: Market Share Scenarios and Policy Signals

By 2030, most forecasts expect only a small share of heavy-duty fleets to run on hydrogen. Within that slice, H2-ICE may take a meaningful share where infrastructure and duty cycles align. By 2035, under ambitious policies, hydrogen (combustion + fuel cell) could cover a double-digit share of new sales in some regions, with the split between H2-ICE and fuel cells determined by fuel prices, incentives, and OEM strategies.

FAQ: Hydrogen Combustion Engines, NOx, and Investment Decisions

Are hydrogen combustion engines just a stopgap before fuel cells take over?

H2-ICE can be seen both as a transition technology and a niche long-term solution. In some markets, it may provide a faster route to hydrogen adoption by leveraging existing engine plants and mechanic skills. Over time, fuel cells may dominate where efficiency and range are critical, while H2-ICE persists in off-road, mixed-duty, or cost-sensitive segments.

How serious are NOx emissions from H2-ICE?

Hydrogen combustion eliminates CO₂ at the tailpipe but does not automatically eliminate NO_x. Without proper combustion tuning and aftertreatment, NO_x can be comparable to or even higher than in diesel engines. OEMs therefore design H2-ICE systems with EGR, optimised injection, and catalyst systems to meet tight regulations.

Is green hydrogen availability a bigger constraint than engine technology?

Yes. In most regions, the availability and price of green hydrogen are more critical constraints than whether engines are combustion-based or fuel-cell-based. Fleet operators should evaluate hydrogen powertrain options jointly with long-term fuel supply agreements and infrastructure plans.

How should fleets choose between H2-ICE and fuel cell trucks?

Key factors include duty cycle (stop-start vs long-haul), required range, refuelling opportunities, hydrogen price, and access to maintenance expertise. H2-ICE may be attractive for high-power, moderate-range, depot-based operations, while fuel cells may be better for long-haul corridors with fewer refuelling stops.