§ Mr. ChopeTo ask the Secretary of State for the Environment, Transport and the Regions what emissions are produced from the use of a gallon of(a) unleaded petrol, (b) super unleaded petrol and (c) lead replacement petrol. [101093]
§ Mr. HillThere is no fundamental difference in emissions produced by any of these grades of petrol, the primary combustion products being carbon dioxide (CO2) and water vapour. Combustion of one gallon will produce approximately 10.7 kg of CO2 and 4.3 kg of water. Small amounts of secondary combustion products can also be created, but the actual amounts will vary from vehicle to vehicle depending on the combustion efficiency of the engine in which the fuel is burned and the efficiency of any exhaust gas after-treatment that may be fitted. These secondary pollutants are mainly comprised of hydrocarbons (HC) arising from unburned or partially burned fuel, oxides of nitrogen (NOx), carbon monoxide (CO) and particulates. Depending on the level of sulphur in the fuel, sulphur compounds can also be produced. Other compounds, resulting from the use of fuel additives such as, for example, potassium that is used in lead replacement petrol, may also be emitted in trace concentrations.