Measuring the emissions of non-road mobile machinery

During this monitoring peculiar emissions were observed, especially with diesel locomotive and with heavy machinery. For example with diesel locomotives, that are primarily concerned with shunting, the engines are idling for 80% to 90% of the time. During this idling, the NOx emissions are often much higher than during load conditions which are covered in the official test procedure. In these instances, fuel consumption is relatively low. In several cases, it is observed that half of the harmful emissions occur during idling and during very low engine load conditions. For fuel consumption this applies to a lesser extent. Still, a mere 10%-20% of fuel savings can be achieved when the engine is switched off during (long) idling periods.

Inland vessel and train engines roughly compare in engine size and yearly engine work performed to 3 to 6 truck engines. The emissions of current trains, inland vessels and construction machinery are disproportionally high compared to those of modern trucks.

Compared to the heavy-duty and light-duty emission legislation for road vehicles, the current Stage-IV emission legislation for non-road mobile machinery is lagging years behind. Often, emissions in normal use, are many times higher than prescribed by legislation. The emission limits themselves constitute only a fraction of the problem. TNO’s monitoring programs show that the formal monitoring test procedure for determining the emissions of NRMM, only partially covers these real-world usage for this type of machinery.

Based on this monitoring programme TNO observes the following:

• Both locomotives and excavators are idling most of the time (50%-90%). In that case, NO_x emissions are rather high. Typically, emissions are three times higher compared to normal use. Idling does not or hardly fall within the scope of current NRMM testing procedures.
• In many occasions, harmful emissions can be decreased by 50%. This can be achieved by using rather simple instructions regarding engine load and switching off the engine in a timely manner, in combination with proper emission monitoring.
• Although idling does not have a very large effect on fuel consumption and CO₂ emissions, in many concrete examples a reduction of 10% is still feasible by switching off the engine in a timely manner.
• NO_x emissions of such machinery are 10 to 100 times higher compared to a truck-trailer combination with similar load and fuel usage. Especially for urban construction projects and urban shunting yards, these will be a major source of the NO₂ concentration in the atmosphere.
• Depending on the age of the mobile machine, it meets either Stage-IIIa, Stage-IIIb, or Stage-IV legislation. This is of significance for the maximum allowed emissions of particulate matter, which emission limits decreased significantly. A large number of construction machines, diesel locomotives and inland vessels in the current Dutch fleet are relatively old and comply with the older requirements. Setting requirements for inner-city use – for example by only allowing Stage-IV machines with a diesel particulate filter – would fit into city policy focused on low emissions zones for truck traffic.
• The new Stage-V legislation, that is due to come into effect around 2020, does not completely solve aforementioned issues. Testing procedures deviate from the normal use observed by TNO. Moreover, required monitoring on some mobile machines has the same caveats.

Below, you can download relevant reports and presentations on measuring the emissions of non-road mobile machinery. Furthermore, you find links to related webpages on emission measurement.

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