AdBlue
AdBlue is a registered trademark for AUS32 (Aqueous Urea Solution 32.5%). It is a solution of high purity urea in demineralised water (32.5%) used as a supplementary operating fluid (reducing agent) in diesel-powered vehicles using selective catalytic reduction (SCR) to improve exhaust emissions. AUS32 is primarily produced in Europe by BASF and AMI, although many other companies manufacture their own similar solutions in varying quantities.
AUS32 is carried onboard the vehicle in a tank separate to the fuel system, and is sprayed into engine exhaust gases in a special catalytic converter. It is a thus a common misconception that AUS32 is a fuel additive, whereas in actual fact it remains totally separate from the fuel system. When properly circulated into the exhaust gases of an SCR-equipped vehicle, the oxides of nitrogen formed by combustion of diesel fuel are converted by a chemical reaction into their basic and non-polluting forms, nitrogen and water. A typical SCR system uses an amount of AUS32 equivalent to approximately 3 to 5% of the vehicle’s fuel consumption.
In order to ensure that the SCR system continues to work effectively, care must be taken to ensure the purity of the catalyst and the reducing agent. Even small amounts of contaminant can severely impact the performance of the SCR system. Manufacturing quality control for AUS32 solutions is governed by DIN standard 70070.
SCR systems using AdBlue are currently fitted to many trucks and buses manufactured by Mercedes-Benz, Volvo Trucks, DAF Trucks and Iveco, however, the use of AdBlue as a reducing agent in SCR systems is hindered by its relative unavailability. Schemes are underway in Europe, and to lesser extents in Australasia and North America, to improve the network of distributors for AdBlue and other SCR additives. As part of these schemes, internet-based tools have been developed to map the locations of AUS32 filling stations, reflecting plans for small-scale use of SCR systems in private vehicles, as well as corporate fleets.
