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AMF - Implementing Agreement on Advanced Motor Fuels

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Annex 25: Fuel Effects on Emissions from Non-Road Engines

Final Report

Fuel Effects On Emissions From Non-Road Engines


The emission regulations for non-road engines are less stringent than for on-road applications. A diversification of automotive diesel fuel and heating oil has started. As aromatics and sulphur is reduced in automotive diesel, it is expected that the aromatics and sulphur content of heating oil will not be reduced or might even increase. Some additives like cetane enhancers and lubricity additives might be left out of heating oils.

The engines used in hand-held equipment like chain saws and trimmers and also in equipment like lawn movers are quite simple, and therefore the specific emissions are extremely high compared for example with modern catalyst equipped gasoline cars. The emissions from small engines can be reduced by improving fuel quality and also by applying simple exhaust after-treatment systems. People using these small engines are normally subjected to the exhaust fumes. Therefore there is also in this case a clear concern for occupational safety.

This project recognizes the current international developments on the issue of fuels for and emissions from non-road engines, and also responds to the Strategic Plan on IEA AMF.

The main objective is to produce a document on the effects of fuel quality and exhaust gas after-treatment on emissions from non-road machinery, both diesel and gasoline powered engines. On the international level, new emission regulations and fuel specifications for non-road machinery are under discussion. It is in the interest of the international community to stimulate a positive development in the reduction of emissions also from non-road machinery.

Due to the vivid ongoing discussions, the results of the study should be made available publicly as soon as possible. In addition to the conventional way of reporting, the results will also be made available over the IEA AMF web pages, the IEA AFIS Fuels Update newsletter and in technical conference papers.

The work will include experimental work with different combinations of engine, exhaust gas after-treatment and fuel. The work will cover both compression and spark-ignited engines. The main fuel parameters to be varied are fuel sulphur content and content of aromatic compounds.

In addition to the experimental work, the reporting will also cover work that already has been published. Such material is available from studies in Finland, and this information will be translated into English and used in the reporting.

The Annex came active on May 2001 and was completed summer 2003. Existing data has been put on the IEA AMF web site since the autumn of 2001. Measurements were carried out with small gasoline engines and non-road diesel engines. The objective of this Annex was to study how fuel quality affects the exhaust emissions from engines mentioned above.

The measured small engines were a 2-stroke chainsaw engine, and a 4-stroke OHV engine, which could be used in different applications. Measurements were done with three different fuels, with and without catalyst. The results clearly demonstrate that using a good quality fuel (e.g. low sulphur, low aromatics) and a catalyst gives the best outcome in overall emission levels from these small engines.

In the second part two different diesel engines were tested with five different fuels. Two of the fuels were biodiesel blends. The engines were chosen to represent old and new engine technology. The old engine (MY 1985) was produced before EU emission regulations were in place, and the new engine fulfilled the current EU Stage 2 emission limits. With the new engine comparison with and without oxidation catalyst was done using two fuels. The results in general are similar compared to the results from the small gasoline engines: fuel quality has an effect on the emissions and when combining a good quality fuel (e.g. low sulphur, low aromatics) and an oxidation catalyst the emission levels are significantly reduced.


  • Finland
  • France
  • Sweden
  • USA

Operating Agent

Timo Murtonen
VTT Processes, Finland