Tracerco, a division of Johnson Matthey plc, is to begin trials of a molecular AdBlue quality tracer this month in collaboration with Transport for London (TfL). The tracer was developed in the UK by Tracerco to determine potential adulteration or contamination of AdBlue solution once in the vehicle tank. The tests will determine the stability and accuracy of the tracer and preliminary results will be available in early March, confirmed Matt Darwood, Tracerco's Fuel Tagging Commercial Manager.

"A year ago we were approached by Cefic AdBlue producers* to develop a system which could be used as a quality assurance check in urea," Darwood explains. "The test has to be used in the field, and it can detect dilution to a level as low as 5%. This is tested using a hand-held analyser which we also developed.�?

AdBlue for the London trial is being supplied by Dureal. The company has set up a 2,250 litre storage and delivery unit (SDU) at a large bus depot in North London. The AdBlue will be "tagged" with the Tracerco molecular solution to a concentration of 12 ppm, and data will be gathered on the tracer's performance over a period of two weeks.

The tracer trial involves at least eight buses fitted with Johnson Matthey SCR systems. This is part of a larger trial of both SCR and EGR buses being run by TfL which aims to determine the most suitable technology to adapt for the fleet of up to 1,000 buses by 2011.

"We cannot control what drivers use in their tanks but we can do our best to ensure the correct quality of AdBlue is used"

Walter Cremer, Sector Manager for the Automotive Grade Urea group within Cefic, confirmed that the organisation pursued the development of a tracer in response to national transport ministries seeking to rule out the potential misuse of AdBlue. "We cannot control what drivers use in their tanks, but we can do our best to ensure the correct quality of AdBlue is used. The concern is to keep sub-standard urea, which may poison SCR catalysts, out of the supply chain," Cremer explained.

"Our main concern is that there is no impact on the price of AdBlue"

Truck manufacturers, though keen to protect the sustainability of the SCR technology they have developed, have not given unqualified support to the initiative. ACEA, the organisation that represents the OEMs, has taken no official line on the development of a tracer. "Our main concern is that there is no impact on the price of AdBlue," ACEA sources said. A senior executive of one leading truck manufacturer said "Having a mandatory tracer in AdBlue is good for AdBlue manufacturers and it would enable us to see who has produced the solution. However, it doesn't give any guarantees. We are still looking for a good tool to analyse AdBlue content.�?

"To perform full chemical analysis at the roadside would be too cumbersome. This is an alternative"

AdBlue producers dismiss claims that they are aiming to restrict competition by developing an origin tracer. "We want to allow OEMs to safeguard their technology by protecting catalysts," one leading producer said. "To perform full chemical analysis at the roadside would be too cumbersome. This is an alternative."

At present there is no statutory requirement to include a tracer in AdBlue produced to the DIN 700070 standard. However, the latest draft of the ISO standard which will supersede the DIN specification allows for the incoporation of a tracer when the technology becomes available.

The European Commission's DG ENTR is thought likely to examine the possible inclusion of AdBlue tracers in Euro 4 and 5 technical legislation. Existing OBD measures and proposals for spot checks on engine-out NOx levels legislate for detection of malfunction, but in SCR systems these would not necessarily be an indication that off-spec AdBlue is being used in the tank. Competition issues are raised by the EC however, given the small group of AdBlue producers involved, and Tracerco's status as the only supplier to bring a tracer to commercial trial. This could be overcome, suggests Yara's Technical Support Director Ernst Strutz, by seeking the cooperation of an independent authority both to license AdBlue producers and the administration of tracer materials.

The results of the Tracerco trial in London buses will be presented to commercial vehicle OEMs, AdBlue producers and other industry representatives in March.

*The Cefic Automotive Grade Urea sector group (AGU) includes Adubos de Portugal, AMI Agrolinz, BASF, Fertiberia SA, SKW Stickstoffwerke Piesteritz GmbH and Yara International SA.