Fuel Cost & Carbon Impact Calculator

Project your future fuel spend and emissions using Bio-LNG and assess the opportunities for your fleet.

Notes on the model

This model is intended to provide an indicative comparison of fuel usage between diesel and Bio-LNG vehicles. The default fuel economy value for Bio-LNG is based on anonymised refuelling transaction data at Gasrec stations over multiple years.

The model is based on high-pressure direct injection (HPDI) LNG vehicles and assumes a 6% diesel substitution rate in combustion. We’ve used this vehicle format because we hold the most robust operational data for this vehicle type.

All other operating conditions—including payload, aerodynamics, tyres, load profile, route etc —are assumed to be identical.

  • The emissions factors are sourced from the UK Government’s 2024 greenhouse gas conversion dataset, published annually by the Department for Energy Security and Net Zero (DESNZ). This is the latest dataset at the time of writing.

    The emissions factors used in this model are:

    • Diesel: 3.1238 kgCO₂e/litre

    • Bio-LNG: 0.5251 kgCO₂e/kg

    • Bio-CNG: 0.6453 kgCO₂e/kg

    For ease of reading, we’ve expressed emissions in tCO₂e (tonnes of carbon dioxide equivalent), calculated by dividing standard kgCO₂e factors by 1000.

    The emissions factors for gas and diesel are well-to-wheel (WTW) and account for:

    • Tank-to-wheel (TTW) emissions – direct exhaust emissions from fuel combustion, Scope 1 under the GHG Protocol.

    • Well-to-tank (WTT) emissions – upstream emissions from fuel production, refining, and distribution, typically reported under Scope 3 (indirect emissions), although some companies might include them in extended Scope 1 calculations for transport fuels.

    Outside of scope emissions are excluded.

    The diesel factor is the standard UK forecourt diesel factor which includes a biofuel blend.

    Finally, please note the methodology used here is purely for indicative purposes and is not intended to demonstrate a methodology for reporting emissions.

  • Gas is measured in kilograms, a stable unit of mass that avoids the variability introduced by volume or density under different environmental conditions.
    The economic case for Bio-LNG (and Bio-CNG) rests primarily on its energy density relative to diesel:

    1 kg of Bio-LNG = 1.38 litres of diesel
    Therefore 1 kg of gas contains more usable energy than 1 litre of diesel and will typically allow a vehicle to travel further per unit.

    When Bio-LNG and diesel are priced within a similar range, this differential can lead to notable cost-per-kilometre savings.

  • Fuel efficiency for gas vehicles is typically measured in:

    • km/kg (distance travelled per kg of gas), or

    • kg/100km (kg of gas required per 100 km)

    These are inverse measures. To convert between them:

    Kg/100km = 100 ÷ (km/kg)
    Therefore, 4km/kg is the equivalent of 25kg/100km. And 5km/kg is the equivalent of 20kg/100km.

    We’re using km rather than miles to avoid mixing metric and imperial systems in a single metric.

    The default value of 4.5km/kg is a realistic efficiency based on the data we have and, from anecdotal data, is comparable to a diesel efficiency of around 8.5mpg.

    It’s possible to make a direct conversion between MPG and km/kg but this would not account for differing vehicle efficiencies across the two technologies.