Like it or not, new exhaust emissions legislation is coming to a truck near you. Currently, from October 2006, all newly registered commercial vehicles must conform to new, cleaner Euro 4 emissions standards.

The way in which most European manufacturers have tackled the problem of reducing emissions is by the use of Selective Catalytic Reduction (SCR). The basic problem they face is to cut the amount of acid rain causing Nitrous Oxide (NOx) and smog-inducing Particulate Matter (PM) that is pumped into the atmosphere by the diesel engines that power their vehicles. Compared with Euro 3, this means cutting the levels by around 40 and 80% respectively. Only Scania and MAN have opted to use Exhaust Gas Recirculation – MAN now says it will offer both technologies on some engines – so if you buy a Daf, Iveco, Volvo, Renault, Mercedes, Foden or Seddon you will buy SCR.

SCR is an aftertreatment solution that employs a series of catalysts between the exhaust manifold and tail pipe to reduce the exhaust gases to harmless nitrogen and water vapour; leaving small traces of ammonia. An engine using SCR can be tuned to burn the fuel more efficiently, thus reducing the PM in the combustion chambers.

In order for the catalyst to work, it requires an extremely pure form of urea to be injected into the exhaust gas stream. The urea acts as a reagent in the chemical reaction and without it the catalyst will not work and emission levels will not be controlled.

This urea solution is currently produced and marketed by five companies throughout Europe. Generically it is known as AdBlue but, as our introduction indicates, it will also be sold as Air1, NOxCare, Dureal and SkyBlue.

Currently, only DaimlerChrysler has SCR-equipped vehicles in production. The Stuttgart-based manufacturer has reacted quickly to tax incentives for early introduction of Euro 4 and 5 in its home country and now offers its Actros range at Euro 4 and 5. Reports suggest that only 600 vehicles have been delivered to date – mainly in Germany – and so the supply of the all-important AdBlue has not become a national issue. But, as we approach the legal implementation date for Euro 4, more manufacturers will bring SCR vehicles on line and more and more operators will buy them.

Once mandatory, it is estimated that by 2010 the UK road haulage industry will be using nearly half a million tonnes of AdBlue a year. So the burning question is, how will it be marketed and distributed?

ROADWAY spoke to two leading producers of AdBlue to find out. Chemical company Yara is the biggest producer of urea in Europe and has been involved in the development of SCR and AdBlue from the start.

The company has already set itself up to supply urea for SCR applications in power generation, incinerators and ships. Yara says that, initially, urea will not be available on petrol forecourts. None of the oil companies produce urea but they are watching to see how the market might develop. Yara has appointed a key accounts manager to work with the oil companies to develop a national network for its urea product, Air1, and is hopeful that Air1 will be available from pumps on filling station forecourts in the future.

However, Yara has established a pan-European agreement with chemical distributor Brenntag. Yara's main activity in the UK is being led by Paul Norman. Norman explains: 'With Brenntag we have set up a bulk delivery system to operators' yards. Operators can order centrally and the AdBlue, as part of a total service package, will be delivered to the operators to bulk storage tanks or in exchangeable 1000-litre Intermediate Bulk Containers (IBCs), with dispensing equipment.

'Another option includes 10-litre canisters which are viewed as a getyou- home package – most trucks will cover 300km on five litres of AdBlue. AdBlue is safe to handle and store, so a container can be carried on the vehicle for emergencies,' he adds. Yara is also setting up a network of local distributors and sales points for get-you-home containers.

During our conversations with the suppliers, two key points about SCR and AdBlue came to light.

Firstly, in 2007 the European Union is looking to enforce Euro 4 by fitting emissions detectors to the exhaust systems in trucks. This means that if the engine is running dirty - due to lack of AdBlue or a system failure in the catalyst or EGR system - the engine management will activate a torque limiter on the engine output. This will only become effective once the engine is stopped and restarted, but will be a great incentive to ensure that emission control systems are not being abused.

The second point is the maintenance of the product's purity and adherence to shelf life. Urea is a commonly available fertiliser which normally comes in crystalline form. Adding water will place it in solution therefore making it usable in an SCR system. Both Yara and GreenChem told us that, unless AdBlue meeting DIN 70070 standard is used, it will severely affect the life of the catalyst and could in extreme circumstances damage it fatally. This will result in expensive replacement and warranty invalidations, not to mention the risk of being caught running illegally.

In order to maintain purity AdBlue must be stored in non-metallic or lined containers, between -10 and +40°C and it only has a shelf life of one year.

Dutch company GreenChem AdBlue Solutions was responsible for registering the AdBlue brand name for SCR urea in 2003. GreenChem passed over the rights, making it the generic term for SCR urea solution.

The company has 13 urea manufacturing operations in Europe including the UK and Ireland. It says that unlike its competitors . multinational chemical producers . it is totally focused on AdBlue production and supply. GreenChem says it believes 75% of AdBlue will be delivered directly to operators. premises and, based on this, it is focusing its UK network around local independent fuel distributors, most of whom have good relationships with operators because they supply their bunkered fuel and lubricants.

GreenChem says it will supply major fleets directly and is working to establish a network of filling stations that will stock small five-litre containers of AdBlue. It believes that it will be some time before the oil companies will allow AdBlue to be dispensed on forecourts. In addition, GreenChem is working with truck manufactures to make AdBlue available from dealerships. GreenChem will also offer stand-alone filling stations in operators. yards which could be purchased or leased.

The company, like its competitor, will supply its product in exchangeable 1000-litre IBCs or through bunkering and will supply all the necessary specialist storage tanks and dispensing systems. GreenChem expects one litre of AdBlue to cost £0.45, but cannot guarantee a standard price across the UK if operators source AdBlue via their network of independent fuel suppliers, because they are allowed to price competitively. For more information go to: www.greenchem-adblue.com or www.yara.co.uk.