What fuel do road trains use?

Mostly diesel. Modern road trains—multi-trailer heavy trucks common in Australia and used in parts of North America—primarily run on ultra-low-sulfur diesel (ULSD) because it offers high energy density, proven reliability, and widespread refueling infrastructure in remote regions. In specific corridors or pilot projects, operators also use biodiesel blends, renewable diesel, liquefied natural gas (LNG) in dual-fuel setups, and, to a limited extent, hydrogen or battery-electric power for shorter or controlled routes.

The dominant choice: ultra-low-sulfur diesel

ULSD remains the standard fuel for road trains in 2025. Heavy-duty diesel engines deliver the torque, range, and durability needed to haul extreme weights over long distances and unsealed roads. Extensive diesel refueling networks across remote areas—especially in Australia’s Northern Territory, Western Australia, South Australia, and Queensland—make ULSD the most practical option. Emissions controls such as selective catalytic reduction (SCR) systems using diesel exhaust fluid (AdBlue/DEF) help fleets meet current standards without sacrificing performance.

Other fuels and emerging options

While diesel dominates, some operators adopt low-carbon or alternative fuels where supply chains, costs, and performance align. These choices are growing but remain niche outside established corridors and mine operations.

The list below outlines fuels increasingly seen with road-train-capable prime movers, plus where and why they’re used.

• Biodiesel blends (e.g., B5–B20): “Drop-in” blends that can lower lifecycle emissions. Most OEMs widely allow up to B5; B20 use depends on engine approvals and maintenance practices. Availability is better near urban hubs than in remote outback corridors.
• Renewable diesel (HVO): A drop-in, paraffinic diesel with lower lifecycle CO2 and good cold-flow properties. Supply in Australia is expanding via imports and trials, with growing use in heavy transport and mining, but broad availability in remote regions is still limited.
• Liquefied Natural Gas (LNG) and dual-fuel diesel–LNG: Cuts particulates and NOx and can reduce CO2 versus straight diesel. Requires cryogenic tanks and dedicated supply, so it’s used where LNG providers operate (notably parts of Western Australia and the Northern Territory) and in some mine-to-port lanes.
• Compressed Natural Gas (CNG): Less common for full road-train duty due to tank volume and weight penalties; more viable for shorter regional hauls and urban operations.
• Liquefied Petroleum Gas (LPG): Rare for modern heavy prime movers; generally not used for true road-train combinations.
• Hydrogen (fuel-cell or hydrogen ICE): Early pilots in Australia and North America show promise for heavy long-haul, but infrastructure is sparse and vehicle availability limited. Most deployments are in trials or controlled-use cases.
• Battery-electric: Proven for multi-trailer combinations on short, predictable routes or within mining precincts and regional shuttles. Range, charging times, and payload trade-offs currently limit suitability for very long, remote road-train routes, though technology and battery-swapping models are advancing.

In practice, fleets adopt alternatives where reliable supply and operational economics line up with emissions goals; elsewhere, they continue to rely on diesel.

Why diesel still dominates in 2025

Diesel’s advantages are straightforward: unmatched energy density for long, heavy runs; mature, rugged engines; extensive refueling and maintenance networks; and predictable costs and performance in extreme heat and dust. Until alternative-fuel infrastructure reaches remote corridors—and vehicles consistently match diesel for range, payload, and uptime—ULSD remains the default for most road trains.

Regional nuances

Australia is the global epicenter of true road trains, especially in the NT, WA, SA, and QLD, where distance and payloads are extreme. Canada and parts of the United States run multi-trailer combinations (e.g., turnpike doubles), generally on diesel. Alternative fuels are more common near ports, mining operations, and along specific corridors with dedicated supply, while remote routes overwhelmingly stick to ULSD.

Operator considerations when choosing fuels

Fleet managers weigh multiple operational and business factors before moving away from conventional diesel for road trains.

1. Range and refueling/charging infrastructure along the entire route
2. Total cost of ownership (fuel price, maintenance, residual value, and uptime)
3. Payload impact from heavier or bulkier tanks/batteries
4. Emissions targets, regulations, and potential incentives
5. Engine warranties and OEM approvals for specific fuels and blends
6. Performance in high heat, dust, and remote conditions

These considerations usually favor diesel today, with alternatives adopted where infrastructure and economics make sense or where emissions targets demand them.

Bottom line

Road trains predominantly run on ultra-low-sulfur diesel because it reliably delivers the range, power, and support needed in remote, heavy-haul operations. Alternatives—biodiesel blends, renewable diesel, LNG dual-fuel, hydrogen, and battery-electric—are emerging in defined corridors and trials, but widespread substitution depends on infrastructure, vehicle availability, and cost competitiveness.

Summary

Most road trains use ULSD. Some fleets blend in biodiesel or switch to renewable diesel where available. LNG dual-fuel appears in corridors with dedicated supply, while hydrogen and battery-electric options are in early, route-limited deployments. For the foreseeable future—especially in remote heavy-haul—diesel remains the mainstay.