Euro 4 Emissions
In October 2006 the EURO 4 engine exhaust gas emission levels came onto the statute books for all LGV's first registered from this date. This again, as with all the other EURO levels, required a substantial reduction of 4 main pollutants. In relative terms this meant a reduction from EURO 3 levels of 30% for Nitrogen Oxide & Nitrogen Dioxide (NOx), Hydrocarbons (HC) & Carbon Monoxide (CO) but a much higher 80% for Particulate Matter (PM).
Currently engine manufacturers use 2 methods of achieving EURO 4. One uses exhaust gas recirculation (EGR), passing exhaust gases back into the engine, to reduce NOx then a post combustion particulate filter (DPF) to tackle PM.
The other uses "Selective Catalytic Reduction" (SCR) which is a post combustion treatment that involves injecting Urea, the catalyst, in a solution (commonly called Ad Blue) into the exhaust system. In the heat of the exhaust gases the Urea hydrolyses into ammonia and once the ammonia and NOx pass through the catalytic converter all that is emitted is Nitrogen (N2) & water (H20) .
The jury is still out on which of these systems is the "best" solution for customers. Both have their own merits and downsides which has promoted an ongoing fierce debate in the industry over which is the better system.
Potential operator impact
6 months after EURO 4 introduction the ongoing manufacturer debate has caused confusion within the industry with buying patterns being disrupted due to the uncertainty over the relative merits and downsides of the EGR & SCR systems.
Objectively when looking at the 2 systems EGR adds little to the weight of a vehicle but causes an increase in fuel consumption (typically 2%), has an impact on the lubrication system (higher quality oils more oil changes), generates high levels of heat (restricted torque), has an unknown life for the expensive diesel particulate filter (DPF) with MAN, one of the fiercest advocates of the EGR system, quoting £4,000 (MAN say the DPF should last the life of the vehicle). Currently EGR is a solution unlikely to be able to achieve the EURO 5 levels in 2009 on its own. At this time MAN & Scania are the only truck manufacturers promoting EGR in LGV's in the European market as their EURO 4 solution although other truck manufacturers have developed this solution and may market it in other countries.
SCR will reduce fuel consumption (typically 5%), requires no additional parts on the engine, has a known life for a cheaper catalytic converter and will allow full compliance with EURO 5 (at a higher dosage of urea which EURO 4 compliant engines can not retrospectively be adjusted to achieve). On the negative side a urea system is added to the vehicle which involves another tank to fill adding chassis weight (typically 100 - 150kg with a full tank, heating & electronic systems) reducing payload and chassis space, will involve the cost (typical dosage is 4% of fuel volume) and inconvenience (fuel station network in development across Europe) of filling with Urea.
At this time all engine manufacturers (including MAN & Scania) only use the SCR method alone on engines to conform to EURO 5.
