You Wei Aw – Asian Diesel Fuel Quality, Vehicle Emissions and Fuel Efficiency


One of the major contributing factors of air pollution arises from the emissions of diesel vehicles and non-road mobile machinery, which are largely determined by the emission-control technology and the quality of the fuel used. It is common knowledge that maximum benefits will be achieved when strict fuel quality requirements are implemented with equally stringent emissions regulations, which enable advanced emission-control technologies and would, in turn, help countries or regions achieve their air quality targets. Governments in some countries have taken this systems approach, particularly with sulfur reduction. Others have not — or have not been able to do so in a coordinated timeline — hampered by factors such as refinery modernizationcosts, or high costs of importing fuels of better quality.

In a region as diverse as Asia Pacific, there are great differences among countries in terms of diesel quality and emission standards. Developed countries generally set stricter standards compared to developing countries. In the developing countries, sulfur reduction is often set as the top priority for fuel quality improvements, and is often carried out in parallel with various biofuels mandates and targets. On the other hand, developed countries which have implemented 10 parts per million (ppm) sulfur diesel focus primarily on tightening and refining other parameters such as cetane number/index, density, polyaromatics, etc. Interestingly, only a handful of countries currently set specifications for off-road diesel, of which on-road diesel dominate the market share in most of these countries.

Biodiesel blending is prevalent in countries with large agricultural industry such as Indonesia, Malaysia and Thailand, where blend levels of B7 and above have been implemented nationwide. Such high blend levels have a direct impact on the quality of conventional diesel fuel, particularly for the properties of cold flow, oxidation stability and biological growth.

Similar to diesel quality, Asia Pacific countries are currently enforcing a wide range of vehicle emission standards from pre-Euro to Euro VI. While most countries have aligned vehicle emission standards with their diesel quality standards, there are a small number of countries that are supplying diesel fuel of incompatible quality with the prevailing emission standard. The lack of expertise in fuel quality and automotive technology is the major reason behind the misalignment of standards. Each country has its own timeline for moving to more stringent fuel standards. In general, Asia Pacific countries have made significant progress toward improving fuel quality in a relatively short time frame.


Based in Singapore, You Wei Aw monitors and provides timely updates on developments of Asia Pacific’s fuel quality and vehicle emission regulations. Since joining Stratas Advisors in 2014, he has contributed to several consulting projects, including the “International fuel quality standards and their implications for Australian standards” paper for the Department of the Environment and Energy in 2014. He has also spoken at a number of regional conferences including the Asia Pacific Fuel Industry Forum 2017 in Melbourne, Australia and International Symposium on Fuels and Lubricants 2018 in Delhi, India. Prior to joining Stratas Advisors, he worked as a Wealth Manager with Maybank Singapore. He earned his Bachelor’s degree with honors in Chemical and Biomolecular Engineering with a specialization in Refinery Processes and Green Processing from Singapore’s Nanyang Technological University.

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