What Is the Cost per Ton-Kilometer for Electric vs. Diesel Mine Trucks?

Electric mine trucks often achieve a lower operating cost per ton-kilometer than diesel trucks when the route has sustained downhill loaded travel, reliable charging or trolley infrastructure, and electricity priced competitively against delivered diesel. The comparison can reverse on short, flat, irregular routes where battery capacity, charging downtime, infrastructure cost, or reduced payload utilization outweigh energy and maintenance savings.

A useful calculation begins with the same functional unit for both fleets:

Cost per ton-kilometer = total haulage cost for a period / total payload moved during that period / loaded haul distance.

The result should be calculated from actual dispatched payload and actual loaded distance, rather than rated truck capacity and nominal route length. A truck that carries less than its planned payload because of material density, loading practice, tyre limits, or road conditions will have a higher cost per ton-kilometer even if its energy consumption appears favorable.

What belongs in the cost comparison?

Fuel or electricity is visible, but it is only one component. A defensible electric-versus-diesel comparison uses the same accounting boundary for both options: truck ownership or lease cost, energy delivered to the vehicle, maintenance labor and parts, tyres, road-related delay, operator or autonomous-system support where applicable, and the productive hours lost to refueling, charging, battery exchange, or unplanned repair.

Capital cost should not be hidden by comparing only fuel expense per hour. If charging equipment has a dedicated purpose for one haul route, its annualized cost belongs in that route's cost per ton-kilometer. Conversely, assigning the entire electrical upgrade to a single truck when the upgrade serves several machines will overstate the electric truck's cost. The allocation should follow expected use and be revisited as fleet deployment changes.

Why route geometry changes the answer

The most consequential difference is usually the relationship between the loaded direction and the gradient. A diesel truck burns substantial fuel while lifting payload uphill. An electric truck also needs significant energy for that climb, but it can regain energy on a loaded descent through regenerative braking. That recovered energy may support the empty return, reduce charger demand, or lower net energy drawn from the site supply.

Regeneration is not free energy, and it should not be estimated from elevation change alone. Recovery is limited by motor-generator capability, battery state of charge, battery temperature, inverter limits, tyre traction, speed control, and the need to preserve a braking margin. If a truck begins a descent with a nearly full battery, it may have little room to accept recovered energy. The control system then relies more heavily on friction or other retarding methods, reducing the expected energy advantage.

Routes with loaded uphill hauling have a different pattern. Electric propulsion can still reduce energy and maintenance costs, particularly when trolley assist is available on ramps, but there is little opportunity for regenerative recovery from the loaded leg. The fleet must reliably receive enough energy during charging windows or under trolley lines to complete the duty cycle without curtailing payload, speed, or dispatch availability.

Rolling resistance deserves the same scrutiny as grade. Haul-road surface condition, moisture, loose material, rutting, and tyre selection can raise energy consumption for either powertrain. A road improvement that lowers rolling resistance can change cost per ton-kilometer more than a minor difference in electricity or diesel price. Using a laboratory-style consumption figure while the route is deteriorated produces a misleading fleet comparison.

Measure payload kilometers, not truck kilometers

Mine trucks travel empty for part of every cycle. Empty travel consumes energy, tyres, and time, yet it produces no ton-kilometers. A cost model that divides all truck kilometers by payload tonnes makes routes with long empty returns look better than they are. The denominator should be the material actually hauled multiplied by the loaded distance, while the numerator includes costs incurred across both loaded and empty movement.

Cycle time links this measure to fleet size. Suppose an electric truck has lower energy expense per cycle but requires an additional charging stop that reduces trips per shift. If the mine must add another truck, charger, or battery set to retain the same material movement, the fleet-level cost per ton-kilometer may rise. The opposite also occurs: a well-timed charging window during loading, dumping, shift change, or planned queuing can have little effect on trips, leaving the electric energy advantage intact.

Payload should be based on onboard payload records reconciled against production systems. Nominal payload is not a substitute. Persistent underloading inflates unit cost; overloading may increase tyre damage, structural fatigue, stopping distance, and road wear. Those penalties can distort an apparent energy saving, especially when a diesel and electric fleet are operating under different payload-control practices.

Energy pricing must reflect delivered energy

Diesel should be costed at the tank after transport, handling, storage losses, and applicable site charges. Electricity should be costed at the charger input, including relevant network charges and the losses between the point of supply and the battery. Comparing retail electricity price with delivered diesel price, or battery energy with fuel purchased at the depot, uses unlike boundaries.

Charging demand can matter as much as kilowatt-hour price. A fleet that concentrates charging at the same time may require a larger connection, transformer, or energy-storage system than a staggered schedule. The infrastructure cost does not disappear because the average electricity tariff is low. Dispatch data should be used to identify simultaneous charging peaks, especially after shift starts, blasting windows, weather delays, or maintenance releases.

Battery energy consumption also needs a reserve policy. A route calculation based on using nearly all installed battery capacity may look attractive, yet it leaves little room for temperature variation, route congestion, road degradation, or a missed charging opportunity. The practical model should use the energy window available under normal operating limits, not the battery nameplate capacity.

Maintenance savings are real, but they are not automatic

Diesel haul trucks have routine maintenance associated with combustion engines, lubrication, cooling, fuel filtration, transmission systems, and exhaust equipment. Electric drivetrains remove or reduce several of these service categories. This can lower scheduled maintenance burden and reduce certain failure modes, particularly where diesel engines operate under high load, dust, heat, and repeated stop-start conditions.

Electric trucks introduce a different maintenance profile. High-voltage isolation checks, cable and connector condition, coolant quality, charger reliability, battery enclosure sealing, and thermal-management performance become availability-critical. On trolley systems, contact components, line tension, electrical isolation zones, and route geometry require attention. The cost model should include the maintenance of the energy-delivery system, not merely the truck itself.

Tyres remain a major common cost and should be modeled separately rather than assumed equal. Vehicle mass, acceleration behavior, retarding strategy, haul-road condition, ambient temperature, and payload control all influence tyre life. Regenerative braking can reduce heat and wear associated with service braking on descents, but rapid torque delivery or poor road management can offset that gain elsewhere in the cycle.

Do not confuse lower energy use with lower unit cost

An electric truck can consume less purchased energy per tonne moved and still have a higher total cost per ton-kilometer during early deployment. Underutilized chargers, spare batteries held for contingency, incomplete workforce readiness, and intermittent grid supply can raise the cost of each productive tonne. These are deployment conditions, not proof that electric haulage is inherently uneconomic. Once truck utilization, charging coordination, and infrastructure loading stabilize, the result can change materially.

Diesel has its own hidden unit-cost risks. Fuel burn rises sharply with idling, congestion, poor road condition, excessive speed changes, and engine derating in hot or high-altitude conditions. A simple liters-per-hour benchmark does not reveal whether the fleet is moving material efficiently. Dividing fuel cost by payload ton-kilometers exposes lost productivity that hourly fuel metrics can conceal.

A practical comparison sequence

1. Define one haul segment with a fixed loading point, dump point, elevation profile, material type, and operating schedule. Combining several unlike routes into one average can conceal the route where electrification succeeds or fails.
2. Use recent dispatch data to establish payload, loaded distance, empty distance, queue time, travel time, idling, and actual trips per operating hour.
3. Build separate energy models for dry and adverse road conditions. Include propulsion, auxiliary loads, battery thermal management, charging losses, and realistic regeneration limits.
4. Convert truck, infrastructure, battery, and support-equipment costs into a consistent period cost. Allocate shared electrical assets according to their expected use rather than assigning them arbitrarily.
5. Test the variables that can alter the decision: diesel price, electricity price, loaded gradient, charger availability, payload distribution, tyre life, road rolling resistance, and annual utilization.

The output should be a range tied to stated operating conditions, rather than a single universal figure. A narrow range is appropriate only when the route, energy supply, payload, and maintenance history are stable. Where those conditions are changing, a wider range is more honest and more useful for fleet planning.

The strongest electric-versus-diesel assessment treats the truck, route, road, energy system, and dispatch cycle as one operating system. Once those inputs are measured on the same basis, cost per ton-kilometer becomes a practical way to identify whether electrification lowers total haulage cost on a specific mine route.