Electric trucks need 50% more power in winter. Scotland maps the 37 chargers still missing on its freight routes

The tool, called ScotVolt, was launched by Heriot-Watt on 13 October. It was developed with the Centre for Sustainable Road Freight (CSRF), a partnership of the universities of Cambridge, Heriot-Watt and Westminster. It models what would happen if Scotland’s HGVs switched from diesel to electric on six corridors: the A9, A90, A1, M74, A77 and A75.

The model runs one-year simulations across 56 scenarios, changing battery size, charger speed and availability, and overnight depot charging. Operators can test their own routes and send feedback.

Why winter changes the numbers

According to the researchers, winter uses about 50% more power than summer for the same network and battery. The reasons are cabin heating, denser cold air and battery efficiency losses.

The 50% figure describes demand on the whole charging network. Per kilometre, the difference for a single truck is smaller. The tool’s assumptions for a fully laden 44-tonne artic range from 1.0–1.7 kWh/km in summer to 1.26–2.15 kWh/km in winter, an increase of about a quarter.

For operators, the practical problem is the grid. Some recharging sites that are “clearly feasible in summer become grid-constrained in winter”, the researchers say. A route that works in July may not work in January.

Winter range is a known issue. Manufacturers test their trucks in the cold, as Mercedes-Benz did with its eActros winter tests.

63 chargers needed, 37 still missing

The research says “at least 63 charging points are needed along major freight routes in Scotland, including the A9, A90 and M74”. Of these, 26 are already built or under development, which leaves 37 still to be delivered.

The earlier Phase 2 report for Transport Scotland showed which sites would be busiest. Annandale Water on the M74 would see around 7,431 charging sessions a year and Dalwhinnie on the A9 around 6,832. Both would need close to 2,000 MWh of electricity a year. The report also found that 11 grid substations would need upgrades.

Bigger batteries, fewer stops

The tool’s other findings are useful for anyone planning to buy electric trucks:

• Battery size: moving from 500 kWh to 1,000 kWh roughly halves the number of trucks that need en-route charging and cuts daily highway charging energy by about 75%.
• Depot charging: it roughly triples the number of charging sites but adds only 20–40% to total daily energy.
• Peaks matter: the number of charging bays depends on how many trucks charge at the same time, not on daily energy use.

According to the Phase 2 report, about 70% of trucks could manage with depot charging alone, and depot plus en-route charging would cover more than 90% of journeys. A separate trial showed that electric HGVs had range to spare on 95% of routes.

“Where and how fleets will charge is still uncertain”

“One of the main barriers to decarbonising road freight is the inherent risk and uncertainty involved in such a large-scale transformation,” said Professor Phil Greening of Heriot-Watt, deputy director of the CSRF.

Dr Siti Fariya, who led the tool’s development, said the aim was “to help fleet owners and operators make decisions about their own transition to electric trucks”.

Chris Ashley, Net Zero lead at the Road Haulage Association, said: “But where and how those fleets will charge is still uncertain for many operators.” He called ScotVolt a practical tool to test real-world scenarios.

Colin Smith, chief executive of the Scottish Wholesale Association, said his members’ trials showed electric HGVs can match diesel on local delivery routes. “The challenge now is making sure Scotland has the right charging infrastructure in the right places,” he added.

The work builds on earlier research, including Transport Scotland’s report on zero-emission HGV infrastructure from 2024.