Colas Rail UK adopts Sulnox Eco to cut emissions and boost diesel fuel efficiency across fleet

Colas Rail UK, part of Bouygues, has adopted Sulnox Eco™ fuel conditioner to reduce emissions and fuel consumption after successful trials in 2024. The move marks Sulnox’s first major step into the rail sector, a global market where 50% of operations rely on diesel—consuming around 33.7 billion litres annually. Colas Rail UK alone uses over 10 million litres of diesel a year, accounting for 85% of its scope 1 emissions.

Details on Colas Rail UK’s rollout of new fuel-efficient fleet

Sulnox Eco is a patented, 100% organic and biodegradable drop-in fuel conditioner that improves combustion, fuel efficiency and engine cleanliness without requiring capex investment.

The trials, supported by Sulnox master distributor A&S International, involved tampers in Rugby and Class 66 and 37 locomotives in York. Emissions were monitored by Socotec and Cura Terrae, showing a 4.5% increase in fuel efficiency, 63.2% reduction in carbon monoxide (CO), 47.5% drop in sulphur oxides (SOx), and notable cuts in particulate matter—32.6% in PM2.5 and 30.4% in PM10.

Based on these results, Colas Rail UK plans to roll out Sulnox Eco across its full locomotive and tamper fleet over 2025 and 2026, also encouraging suppliers to adopt the solution to drive down scope 3 emissions.

Dan Ditri, Head of Energy & Carbon at Colas Rail UK, said: “Cutting emissions is vital for rail’s future, and these trials prove that Sulnox Eco delivers significant reductions while improving fuel efficiency.”

Sulnox CEO Ben Richardson added: “Sulnox is committed to being part of the solution for the rail industry.”

With improved performance and fuel savings, Colas Rail UK could save six figures annually, while helping meet decarbonisation and ESG targets.