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Shell FuelSave - smaller fuel bills and lower emissions for your fleet


Engine combustion and emissions: what actually happens?

    When air and fuel are mixed in the engine, the result of the combustion of carbon, hydrogen and oxygen is CO2 (carbon dioxide) and water. The CO2 emissions are directly related to the amount of fuel the vehicle uses, so if you reduce your fleet's fuel consumption, you'll automatically cut your CO2 emissions by the same percentage.


How much CO2 is produced from a litre of fuel?

    Standard diesel fuels generally contain around 87% carbon by weight, the rest being hydrogen and other very minor components. The amount of carbon in a litre of diesel fuel varies, but this only affects the total CO2 production slightly. Diesel biofuel blends may contain at present up to 5% of a bio-derived component and this can introduce about 0.5% oxygen into the overall blend.



How much CO2 does a vehicle produce?

    Individual vehicles consume fuel at different rates, thereby producing different amounts of CO2 - this chart shows typical fuel consumption for some commercial vehicles:



    It's easy to work out how much CO2 is typically produced by commercial vehicles. The table below shows the CO2 emitted and fuel consumed by different vehicle types over every 10,000km travelled, on the basis that one litre of fuel produces about 2.65kg of CO2:



    For example, a heavy truck covering 100,000km annually will produce 10 x 10,600 = 106,000kg (106 tonnes) of CO2 over twelve months.


How much CO2 could you save by reducing fuel consumption by 3%?

    Using the example of the heavy truck producing 106 tonnes of CO2/year, a fuel consumption saving of 3% will result in 0.03 x 106 = 3.2 tonnes less CO2 produced. In other words, approximately the same amount of CO2 as produced by a medium-sized diesel car in a year (20,000km at 6 litres/100km). So improving the fuel economy of a single truck by 3% in a year returns the same benefit as cancelling out the CO2 produced by a medium-sized passenger car over a year.


So where do biofuels fit in with all this?

    Biofuels have the potential to cut CO2 emissions because the plants they're made from absorb CO2 as they grow. This is released again when the biofuels are burnt. Further CO2 is created as part of the process of growing, harvesting, processing - and distributing the end result, the biofuel. This means that the CO2 benefits of biofuels must be assessed by "life cycle assessments" - in other words, by "well (or fields)-to-wheels" studies. The net CO2 emitted is calculated from the growing of the plant right through to the vehicle exhaust emissions in these studies. A bio-ester made from rapeseed produced in Europe with limited fertiliser use, for example, could reduce well-to-wheels CO2 production by around 50% compared to conventional diesel fuel. An additional 5% blend of this type of bio-ester would therefore reduce well-to-wheels CO2 emissions by around 2.5%.

    Shell FuelSave increases your fuel economy by up to 3% and therefore reduces your emissions and carbon foot print. It is available at no additional cost when you use your Shell CRT / euroShell fuel card from The Fuelcard People.

    You may also be interested in these pages: Up to 3% fuel economy with Shell FuelSave at no extra cost, Shell FuelSave Diesel, Shell FuelSave Unleaded, Shell's Fuel Saving Tips or find your nearest Shell station. Return to the main Shell page by clicking here.