Blue-sky thinking

Date: Monday, July 06, 2015   |   Author: Ian Shaw

The greatest number of changes the LCV sector has seen over recent years are not in greater load capability, nor driver comfort or even operator efficiencies, but in environmental legislation. European exhaust emissions restrictions have been introduced in a number of steps, and will continue to
be so. The latest, Step 6 or Euro6 as it more commonly known, came into force for large goods vehicles manufactured from September 2014 onwards, with a cascading of the requirement through LCV and passenger cars too.
The level of the restrictions and the speed with which they have tightened is unprecedented in any other industry. Casual observers who hold up the motor vehicle as the root of all evil should take a look at the changes in recent years. Euro1 for cars and LCVs came into force in 1993, Euro2 in 1996 for passenger cars and motorcycles, then Euro3 in 2000 for all vehicles. Euro4 arrived in 2005, affecting any vehicle, before Euro5 hit the industry in 2008/09 for passenger and commercial vehicles, with the current Euro6 coming into force in late 2014 and encompassing light passenger and commercial vehicles. However, these seemingly linear changes hide a myriad of detail.
Meeting Euro emissions regulations is, with a few exceptions, relatively straightforward for petrol engines. For diesel, though, it is much more challenging.
Euro5 regulations clamped down on exhaust particulates, which mean many new diesel vans are fitted with standard exhaust particulate filters. (particulates is less of an issue for petrol cars).

Euro6 targets a reduction in nitrogen oxides (NOx) because they are a significant greenhouse gas and air pollutant.
The cut is large: a Euro6 diesel vehicle must emit more than 50% less nitrous oxides than a Euro5 diesel. The cap is 80mg/km, compared with a 180mg/km allowance for Euro5. The reduction from Euro4 to Euro5 was 20%, showing how severe the reduction demanded by Euro6 is. Back in 2000, the NOx limit was 500mg/km.
Diesel engines naturally produce higher levels of NOx than petrol cars. As Euro6 especially affects the standards for diesel-powered vehicles, requiring as it does a further reduction of NOx and hydrocarbon emission levels, the Selective Catalytic Reduction (SCR) system and AdBlue additive are being combined together to meet the Euro6 standard.
Those manufacturers using the system generally have their own model designations for it. Mercedes-Benz calls it Bluetec, Volkswagen Bluemotion, Vauxhall’s nomenclature is BlueInjection SCR, while Citroen has BlueHDi. You get the impression that from a marketing point of view, blue is the new green.

Bish, bash

So rapidly has it been adopted that Bosch automotive development expert has now produced well over one million Denoxtronic exhaust-gas treatment systems. In combination with an SCR catalyst, this AdBlue metering system reduces NOx emissions from a commercial vehicle’s diesel engine by up to 95%. The exhaust gas treatment system also allows the engine to be configured to reduce fuel consumption, with the result that CO2 emissions fall by approximately 3%.
In the SCR method, the Denoxtronic’s metering module injects the AdBlue water-urea solution into the exhaust gas flow at exactly the right mixture. This mixture is computed on the basis of data from the engine electronics, such as engine speed or operating temperature. Ammonia is produced, which reacts with the NOx in the SCR catalyst to produce harmless nitrogen and water.
The big difference with Euro6 and its wide reliance  on AdBlue, is that for the first time the emissions restrictions require the van operator to get involved.
With catalytic converters and latterly particulate traps, the driver or operator played no part – the technology was contained within the exhaust system, and in the event of a blocked particulate trap the only action needed was to run the van at medium engine speed on the motorway to allow the system to go into ‘incinerate’ mode. With AdBlue, however, the driver needs to keep a reservoir topped-up. Failure to do so will not actually shut down the engine as has been mis-reported in some areas, but will prevent it from re-starting after the ignition is switched off. The AdBlue is not added to the diesel itself, but is injected into the SCR unit within the exhaust system.
AdBlue consumption depends on the conditions in which the van is operated, but the average in UK vehicles is generally 5% of diesel use. For example, Citroen claims that a BlueHDi-powered Berlingo with a 17-litre AdBlue tank will last for up to 14,000 miles between fills, and all Citroen dealers carry AdBlue top-up bottles in their parts departments. The price of UK AdBlue is roughly half the gross price of diesel per litre at the pump in the UK. However, it is claimed it reduces the diesel fuel consumption of SCR-equipped vehicles by up to 5%, giving a cost saving back.

Mixed bag

So is filling up with AdBlue going to be problematical, reminiscent of the introduction of unleaded-only cars, for those of us old enough to remember it, or is the infrastructure in place? For van operators it’s a mixed bag.
“Because of the low usage on vans, it is unlikely really that a retail-pumped solution will be required for some time,” says Sean Cole, business manager, at AdBlue specialists Air1/Brenntag – UK & Ireland.
“Also, many light commercial fleets sit side by side with HGV fleets, so those operators will already have product supply in place. However, it’s worth remembering that vehicles with smaller AdBlue tanks will almost certainly need dispensing equipment that has a lower flow rate than the HGV dispensers, so manual options are probably best at this stage,” advises Cole.
“For van-only fleets and small operators, they will be able to use the smaller packs, such as 210-litre drums at their depots if volumes allow, or 10-litre canisters, either at the depot or [which are] widely available on road.
Users should also remember to fill directly from the container it is supplied in, to prevent contamination.”
For most LCV operators,  the small volume top-up bottles will be the easiest solution since larger-scale pumps on the forecourts are aimed at HGV use. However, with its widespread application in diesel passenger cars, AdBlue will soon be far more prolific on the forecourt than LPG or CNG fuels ever were. It’s here to stay, so light commercial vehicle operators need to be AdBlue aware.

The solution's solution to NOx

AdBlue is a 32.5% solution of high-purity urea in de-mineralised water that is clear, non-toxic and safe to handle. It is non-explosive, non-flammable, and not harmful to the environment, advises AdBlue specialists Air1. AdBlue is classified under the minimum-risk category of transportable fluids. It is neither a fuel, nor a fuel additive, and needs to be used in a dedicated tank in the vehicle. Should you spill AdBlue on your hands, simply wash it off with water. Selective Catalytic Reduction (SCR) technology requires the use of the reagent AdBlue (also called Aus 32) to reduce the NOx. The main components of the
SCR system are the SCR catalyst, the AdBlue injection unit, the AdBlue tank and the AdBlue dosing control unit. AdBlue is injected into the exhaust pipe, in  front of the SCR catalyst, downstream of the engine. Heated in the exhaust it  decomposes into ammonia and CO2. When the NOx reacts inside the catalyst with the ammonia, the harmful NOx molecules in the exhaust are converted to harmless nitrogen and water.
For the correct functioning of an SCR system, be sure to only use  high-quality AdBlue. Air1 tells WhatVan? that poor-quality reagent that is  contaminated with foreign matter risks damaging your catalyst.  


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