Standalone Exhaust-gas Aftertreatment for Mobile Machinery and Stationary Applications

Complying with Future Emissions Standards

Whether they're installed in diggers, bulldozers or loading cranes, diesel engines often have a tough job to perform. And thanks to their outstanding performance, reliability and efficiency, they excel in their job. But there's also a fourth characteristic that's becoming ever more important:

if the quality of the air we breathe is to improve, mobile machines have to be environment-friendly, too.

To achieve this goal, legislators have laid down binding limit values for the exhaust emissions of non-road applications, limits that will be tightened up even further over the coming years. In particular, the authorities are targeting an effective and longterm reduction in particulate matter (PM) and nitrogen oxide emissions.

The limits enforced to date have been able to be complied with by optimising the set-up of the engine on the basis of low-emission internal combustion. In their efforts to achieve this, engine developers are essentially confronted with the contradiction that a low-emission combustion process also has the unfortunate side-effect of increasing fuel consumption.

By investing substantial technical expertise and effort, manufacturers have so far succeeded in preventing a noticeable increase in consumption and avoiding the use of external exhaust-gas aftertreatment. But the increasing tightening of emissions limits is intensifying the conflict between reducing soot and nitrogen oxides on the one hand and developing as economical a drive system as possible on the other.

Successive Tightening

Combining these two goals is set to become an even greater challenge in the future:

In 2011, Europe will see Stage IIIB of the EU's emissions directive for the non-road sector come into force, while the Tier 4 interim emissions requirements will also take effect in the USA. Just 3 years later, Stage IV and the Tier 4 final requirements will come into effect in each of the two unions, respectively.

In most cases, the legal requirements can only be met with the aid of additional exhaust-gas aftertreatment with effective, low-maintenance, heavy-duty and long-life pollutant reduction systems. The contradiction between fuel consumption and cutting emissions can to a large extent be solved, and the latitude gained offers scope for outright optimisation of engines' fuel efficiency.