AFC Energy (AIM: AFC), a provider of ammonia-based hydrogen production systems, has signed a US$2 million Joint Development Agreement (JDA) with Komatsu Ltd. and its affiliate, Industrial Power Alliance Ltd., to develop scalable ammonia-powered diesel engine solutions for off-road heavy equipment. Notably, this is one of the first structured industrial JDAs focused specifically on integrating an ammonia cracker (a catalytic reactor that converts ammonia into hydrogen) with a production-relevant diesel engine platform for construction, mining, forestry, and industrial duty cycles.

Komatsu, listed in Tokyo and Osaka, is among the world’s largest heavy machinery manufacturers. The project combines AFC Energy’s ammonia-to-hydrogen cracking know-how with Komatsu’s experience in industrial internal combustion engines (ICEs) to evaluate ammonia-to-hydrogen internal combustion engines as a route to cut diesel consumption while retaining the durability, refuelling speed, and high-load performance required on sites.

TL;DR: AFC Energy and Komatsu are jointly engineering a diesel-engine system that uses ammonia as a hydrogen carrier, with the goal of reducing diesel burn in heavy-duty off-road equipment without relying on full electrification.

Overview of the Joint Development Agreement

The JDA sets a framework to design, test, and integrate AFC Energy’s proprietary ammonia cracking technology with a Komatsu industrial diesel engine. The intent is to confirm both technical feasibility (combustion stability, transient response, emissions compliance) and commercial feasibility (packaging, safety systems, serviceability, and supply logistics) for scalable deployment.

Integrate the ammonia cracker, hydrogen conditioning, and controls with an existing Komatsu diesel engine platform.
Run multi-point and transient duty-cycle tests to quantify diesel substitution potential and efficiency impacts.
Measure regulated emissions and define the aftertreatment/control strategy required for compliance.
Assess scalability for multiple equipment classes and global operating environments.

For context, off-road machines typically must meet stringent pollutant limits (not just CO₂)—for example, EU Stage V and U.S. EPA Tier 4 Final requirements for non-road engines strongly influence combustion strategy, exhaust aftertreatment selection, and onboard diagnostics. Authoritative references include the EU Stage V overview (DieselNet) and the U.S. EPA nonroad engines regulatory pages.

TL;DR: The JDA is an engineering and validation program to integrate an ammonia cracker into a Komatsu diesel platform and prove performance, emissions, and scalability under real heavy-duty cycles.

How ammonia cracking works in a diesel engine (interface and fuel strategy)

Ammonia as a hydrogen carrier vs. direct ammonia combustion: In this concept, ammonia (NH₃) is primarily treated as a hydrogen carrier. The cracker dissociates NH₃ into hydrogen (H₂) and nitrogen (N₂). That hydrogen is then used in the engine. This differs from direct ammonia combustion, where NH₃ itself is injected and burned in-cylinder—an approach that faces additional challenges such as slow flame speed, higher risk of unburned ammonia slip, and potentially narrower stable operating windows.

Likely engine configuration: dual-fuel diesel–hydrogen operation. The most practical integration route for a compression-ignition diesel platform is a dual-fuel diesel-hydrogen engine configuration:

Diesel remains the ignition source (pilot injection) because diesel auto-ignites reliably under compression.
Hydrogen provides supplemental energy and can displace a portion of diesel energy input, particularly at steady mid-to-high loads where cracking and hydrogen flow can be stabilized.
Hydrogen introduction method is typically via intake manifold port injection or controlled mixing upstream of the intake (exact approach depends on backfire risk, packaging, and target substitution ratio).

What diesel substitution could look like (indicative): In dual-fuel modes, it is common for hydrogen to substitute a meaningful share of diesel energy at certain operating points, while not eliminating diesel entirely due to ignition and transient constraints. Practical substitution ratios are application- and calibration-dependent; in heavy-duty cycles, strategies often target a variable substitution window—for example, lower substitution during fast transients and very low loads, higher substitution during stable high-load operation. The JDA’s engineering work will determine the achievable substitution map without compromising knock limits, exhaust temperatures, or emissions compliance.

On-board vs. off-board cracking: For mobile heavy equipment, the most likely architecture is an on-board cracker (mounted on the machine) to avoid hydrogen logistics and enable ammonia refuelling with on-site storage. Off-board cracking (site-based hydrogen generation) can work in fixed industrial settings, but it adds hydrogen compression/storage/dispensing complexity that many remote sites prefer to avoid.

Operating temperature and response time (what matters in heavy-duty duty cycles): Ammonia cracking is a catalytic, high-temperature process (often several hundred °C). Practically, this introduces two important control/operations topics:

Warm-up and thermal management: the system needs a managed heat-up phase and insulation/heat integration to reach stable cracking conditions.
Transient load response: heavy equipment sees rapid load swings (digging, hauling, pushing). The engine’s demanded torque can change faster than the cracker’s thermal system can respond. A robust solution typically uses buffering and control strategies such as (a) a small hydrogen buffer volume, (b) dynamic diesel-to-hydrogen substitution maps that temporarily increase diesel during sudden load steps, and (c) coordinated control of ammonia feed, cracker temperature, and hydrogen flow to prevent lean/rich excursions.

TL;DR: The most practical interface is on-board ammonia cracking feeding hydrogen into a dual-fuel diesel–hydrogen engine, where diesel provides reliable ignition and hydrogen displaces part of diesel energy—especially during steady high-load operation.

Energy density and what it means for refuelling logistics

Energy density strongly impacts tank size, machine packaging, and refuelling frequency. Indicative lower heating value (LHV) comparisons (LHV = usable energy excluding water condensation heat):

Diesel: ~43 MJ/kg (high gravimetric energy density; mature infrastructure)
Ammonia (NH₃): ~18.6 MJ/kg (lower per kg than diesel, but practical as a liquid at moderate pressure/temperature)
Hydrogen (H₂): ~120 MJ/kg (very high per kg, but low volumetric density; storage is complex at high pressure or cryogenic conditions)

Because ammonia can be stored as a liquid under relatively manageable conditions compared with hydrogen, it can be attractive for remote sites seeking fast refuelling and high uptime—especially when battery-electric would require very high-power charging infrastructure and potentially long dwell times.

Authoritative background on ammonia properties and safe handling is available from the NIOSH Pocket Guide for Ammonia and the U.S. DOE overview of hydrogen storage.

TL;DR: Diesel has the highest usable energy per kg among the three, hydrogen is hardest to store onboard, and ammonia offers a middle-ground logistics advantage as a liquid hydrogen carrier.

Expected emissions profile (beyond CO₂) and how it will be managed

CO₂: Tailpipe CO₂ reduction is primarily driven by how much diesel is displaced by hydrogen. If hydrogen energy replaces X% of diesel energy, tailpipe CO₂ can drop by a similar order of magnitude (subject to efficiency changes). Lifecycle CO₂ depends on how the ammonia is produced (conventional vs. low-carbon vs. renewable).

NO_x (nitrogen oxides): Hydrogen addition can increase combustion temperatures and potentially raise NO_x if not controlled. Moreover, since cracked ammonia yields N₂ as a carrier gas, the mixture and combustion phasing must be tuned carefully. Expected mitigations include:

EGR (exhaust gas recirculation) calibration to lower peak flame temperature
Injection timing/pressure optimization and boost management
Maintaining a robust SCR (selective catalytic reduction) system for NO_x control, consistent with Stage V/Tier 4 Final architectures

Particulate matter (PM) / soot: Replacing some diesel with hydrogen typically reduces soot formation because hydrogen contains no carbon and can improve local mixture quality. However, soot outcomes depend on combustion mode and how much diesel remains. A DPF (diesel particulate filter) may still be required depending on certification pathway and engine-out PM.

Ammonia slip (unreacted NH₃): While the concept is to crack ammonia upstream, small amounts of NH₃ can potentially pass through due to incomplete cracking, transients, or leakage. Slip management typically involves:

Cracker conversion monitoring and temperature control to maintain high dissociation
NH₃ sensors in relevant locations (e.g., enclosure, exhaust where applicable)
Oxidation catalysts or slip catalysts where needed, plus control logic to reduce ammonia feed during off-spec operation

These pollutant-control requirements are heavily shaped by non-road regulations and practical OEM practices; see the earlier references to EU Stage V (DieselNet) and U.S. EPA nonroad engines.

TL;DR: Expect lower CO₂ as diesel is displaced, potentially higher NO_x risk without controls, generally improved PM trends, and a need to actively prevent/monitor ammonia slip using sensors, catalysts, and coordinated controls.

Key technical challenges and design constraints (safety, packaging, control)

Ammonia toxicity and leak management: Ammonia is toxic and corrosive; equipment must incorporate leak detection, ventilation, emergency shutoff valves, and robust hose/coupling design. Worker exposure limits and site safety rules will affect enclosure layout and maintenance procedures. Safety references include the NIOSH Pocket Guide for Ammonia and widely adopted codes such as NFPA 400 (Hazardous Materials Code) (where applicable by jurisdiction) that influence hazardous material storage/handling design.

Storage conditions and infrastructure: Ammonia can be stored as a liquid under moderate pressure or refrigeration; the chosen approach impacts tank weight, boil-off management, refuelling hardware, and site permitting. Industrial sites may already handle ammonia (fertilizer, refrigeration), which can reduce incremental infrastructure burden.

Cracker thermal integration: A cracker needs high temperature and stable heat management. For mobile equipment, this usually means integrating with exhaust heat recovery and/or a dedicated burner/heater during warm-up. Design must avoid excessive parasitic losses that would erode efficiency benefits.

Controls under transients: Heavy equipment load profiles are highly transient. The control system must coordinate diesel injection, boost/EGR, ammonia feed, cracker temperature, and hydrogen delivery to avoid torque lag, misfire, or emissions spikes. This is a major differentiator between a lab demo and a field-ready low-carbon heavy equipment powertrain.

TL;DR: The hard parts are safety (toxicity/leaks), onboard storage and refuelling, keeping the cracker hot and stable, and controlling diesel–hydrogen substitution smoothly during fast load swings.

Ammonia vs. electrification for heavy machinery (and other alternatives)

Battery-electric (BEV): Battery-electric heavy equipment can deliver zero tailpipe emissions, but for high-utilization machines it may require very large battery packs, high-power charging (often multi-megawatt for large assets), and careful thermal management. In remote mines or infrastructure projects, grid capacity and charging downtime can be limiting factors.

Hydrogen ICE: A hydrogen internal combustion engine can avoid CO₂ at the tailpipe, but on-site hydrogen supply (compression, storage, dispensing) can be complex—especially where hydrogen delivery is expensive or intermittent. Ammonia can reduce hydrogen logistics by shipping hydrogen in liquid chemical form and cracking it on demand.

Fuel cells: Fuel cell electric powertrains can be highly efficient and quiet, but they often have tighter requirements on fuel purity, thermal/water management, and can face durability/cost challenges in shock, vibration, dust, and high-load transient environments typical of off-road machinery.

Direct ammonia combustion: Direct NH₃ combustion avoids the cracker but can introduce combustion stability issues and ammonia slip challenges; it typically requires substantial engine and aftertreatment development. The ammonia-to-hydrogen route is often viewed as a more diesel-compatible pathway because hydrogen can be metered as a gaseous secondary fuel while diesel retains ignition control.

TL;DR: Compared with BEV and fuel cells, ammonia-to-hydrogen dual-fuel aims to keep fast refuelling and diesel-like duty capability; compared with hydrogen ICE, ammonia can simplify supply logistics; compared with direct ammonia combustion, cracking can reduce combustion/safety complexity at the cylinder level (but adds a hot reactor subsystem).

Implications for fleet operators and OEM engineers (retrofit, TCO, service)

Retrofit vs. new-build: In many cases, integrating an on-board cracker, ammonia tank, sensors, and controls is more straightforward as a new-build option due to packaging and certification. However, higher-value stationary or quasi-stationary assets (e.g., generators, large mining trucks with long service life) may be candidates for retrofit if the system can be packaged safely and validated for compliance.

Total cost of ownership (TCO): Key TCO drivers will include:

Fuel economics: local cost and availability of low-carbon ammonia versus diesel; delivered logistics to remote sites
Capex and integration: ammonia tank, cracker module, controls, and safety systems
Maintenance: catalyst life, filters, sensors (including NH₃ detectors), periodic inspections of lines/couplings, and calibration upkeep
Infrastructure: site storage tanks, dispensing equipment, permitting, and operator training

Service considerations for the cracker: Expect service plans to include catalyst health monitoring, inspection for contamination/poisoning, thermal cycling management, and verification of conversion efficiency to minimize NH₃ slip risk. OEM engineers will also care about maintainability (module access, quick-change components) because uptime is often the dominant KPI in mining and quarry operations.

TL;DR: New-build integration is typically easiest; TCO hinges on ammonia supply cost and infrastructure, while maintenance adds cracker/catalyst and safety-system checks on top of familiar diesel service items.

Use-case scenarios (what changes on site)

Scenario 1: Large mining haul truck (high utilization, remote refuelling). A dual-fuel diesel–hydrogen configuration using on-board ammonia cracking could reduce diesel consumption during long steady hauls and climbs where the cracker can remain at stable operating temperature. The site would add an ammonia storage/dispensing point (with hazardous-material procedures), while the truck retains diesel tanks for pilot ignition and redundancy. Operationally, refuelling remains fast compared with charging, and emissions improvements would be most visible in CO₂ and soot-related PM, with NO_x controlled via tuned combustion/EGR and SCR.

Scenario 2: Mid-size excavator (high transients, idle time, frequent load steps). Excavators experience rapid swings between idle, slewing, and digging peaks. The control strategy would likely use lower hydrogen substitution during rapid transients and idle to avoid lag and maintain stable combustion, then increase substitution during sustained digging or steady work phases. A small buffer and smart substitution mapping become essential to maintain “diesel-like” response.

TL;DR: Haul trucks benefit from long steady load windows that suit cracking; excavators need sophisticated transient controls and buffering to keep response crisp while still displacing diesel when conditions allow.

Commercial structure and strategic alignment

The JDA totals approximately US$2 million, tied to defined technical milestones—an execution model that helps keep development disciplined and aligned with measurable outcomes such as stable hydrogen production, calibrated dual-fuel operation, and emissions results under relevant cycles.

Strategically, the work targets a segment where decarbonisation options are constrained by uptime requirements and infrastructure limitations. For Komatsu, it complements a portfolio approach that can include electrification, hybrids, and alternative fuels—allowing different solutions for different duty cycles and sites.

TL;DR: The milestone-based contract structure emphasizes measurable engineering progress toward an ammonia-to-hydrogen dual-fuel engine suitable for real equipment deployment.

Leadership perspectives

John Wilson, Chief Executive Officer of AFC Energy plc, positioned Komatsu’s engagement as validation of AFC Energy’s ammonia cracking approach for heavy-duty applications and highlighted expansion into industrial verticals that demand high uptime.

Taisuke Kusaba, Chief Technology Officer of Komatsu Ltd., described the collaboration as a step toward evaluating additional decarbonisation methods for Komatsu’s fleet, alongside other pathways the company is exploring.

TL;DR: Both companies frame the project as practical engineering evaluation: AFC Energy on cracking integration, Komatsu on broadening viable low-carbon powertrain options.

Conclusion

The AFC Energy–Komatsu US$2 million JDA targets a specific technical outcome: integrating an ammonia cracker with a diesel engine to enable ammonia-to-hydrogen internal combustion engines operating in dual-fuel diesel-hydrogen mode for off-road machinery. If testing confirms stable transient response, manageable ammonia slip risk, and compliance-ready pollutant control (NO_x/PM), the approach could reduce diesel consumption materially in applications where batteries or pure hydrogen logistics are difficult.

As regulations such as EU Stage V and U.S. EPA Tier 4 Final continue to shape non-road engine design, the winning solutions will be those that combine emissions compliance, safe site operations, and high availability—not just CO₂ reductions on paper.

TL;DR: This project is about proving a field-viable ammonia-cracked hydrogen supply feeding a dual-fuel diesel engine—aiming for real diesel displacement while maintaining heavy-equipment performance and emissions compliance.

FAQ

Q: How does an ammonia cracker integrate with a diesel engine in this concept?

A: The cracker converts liquid ammonia (NH₃) into hydrogen (H₂) and nitrogen (N₂). The hydrogen is then metered into the engine (often via intake mixing), while diesel remains as a pilot fuel to ensure reliable ignition. This creates a dual-fuel diesel–hydrogen engine where hydrogen displaces part of the diesel energy input.

Q: Is this direct ammonia combustion, or is ammonia only used as a hydrogen carrier?

A: The intent is ammonia primarily as a hydrogen carrier: ammonia is cracked to hydrogen, and hydrogen is used in the engine. This differs from direct ammonia combustion, where ammonia is injected and burned in-cylinder, which typically requires different combustion and slip-mitigation approaches.

Q: What emissions should fleet operators expect beyond CO₂?

A: In addition to lower CO₂ from reduced diesel use, the key considerations are NO_x control (managed by calibration, EGR, and SCR aftertreatment), particulate matter/soot (often reduced as diesel is displaced), and preventing unburned ammonia slip through high cracker conversion, monitoring, and appropriate catalyst/control strategies.

Q: Is using ammonia as a fuel safe for heavy equipment operators?

A: It can be, but it requires industrial-grade safety design and procedures because ammonia is toxic. Typical measures include leak detection sensors, ventilated/enclosed components, automatic shutoff valves, compliant storage/dispensing hardware, and operator/maintenance training aligned with applicable hazardous-material codes and exposure guidance (e.g., NIOSH ammonia guidance and relevant fire/hazard codes such as NFPA 400, as adopted locally).

Q: How does ammonia compare with battery-electric for remote mines or large construction sites?

A: Battery-electric can eliminate tailpipe emissions but may require very large batteries and high-power charging infrastructure that can be difficult to deploy in remote locations. Ammonia-to-hydrogen dual-fuel systems aim to keep fast liquid refuelling and high utilization while reducing diesel consumption—often better aligned with sites where electrical infrastructure is limited or downtime is costly.

AFC Energy and Komatsu Partner for $2M Ammonia Engine Project

Introduction