Science news

FMI's researchers publish about 350 peer-reviewed articles annually.

In Science News we publish current information about FMI's studies on the weather, the sea and the climate.

« Back

Renewable fuels reduce diesel exhaust particle and black carbon emissions

Renewable fuels reduce diesel exhaust particle and black carbon emissions

Recent study showed that renewable diesel fuels enable mitigations of particulate and climate-warming black carbon emissions of traffic. At the same time, they help tackle urban air quality problems.

The use of fossil fuels in traffic is a significant source of air pollutants and greenhouse gases in rapidly growing and densely populated cities. The influence of fuel (European, Indian and renewable diesel) and driving cycle to emission factors of particulate and gaseous compounds were characterized in a recent study.

Fuel properties and driving conditions were observed to strongly affect exhaust emissions. The exhaust particulate mass emissions for all fuels consisted of black carbon (81–88%) with some contribution from organics (11–18%) and sulfate (0–3%). However, aromatic-free fuel, the renewable MY diesel produced around 20% lower black carbon (BC) emissions compared to the European diesel (EN590) and 29–40% lower compared to the Indian diesel (BS IV).

High volatile nanoparticle concentrations at high WLTC speed conditions were observed with the Indian and European diesel, but not with the sulfur-free MY diesel. These nanoparticles were linked to sulfur-driven nucleation of new particles in cooling dilution of the exhaust. For all the fuels non-volatile nanoparticles in sub-10 nm particle sizes were observed during engine braking, and they were most likely formed from lubricant-oil-originated compounds. With all the fuels, the measured particulate and NOx emissions were significantly higher during the WLTC driving cycle compared to the NEDC driving cycle.

Diesel exhaust emissions including particle number concentration and size distribution along with the particles' chemical composition and NOx were investigated from a Euro 4 passenger car with a comprehensive set of high time-resolution instruments. The particulate and gaseous emissions of a light duty vehicle were characterized using with three different fuels – European diesel (EN590), Indian diesel (BS IV) and Finnish renewable diesel (Neste MY) – over the New European Driving Cycle (NEDC) and the Worldwide harmonized Light vehicles Test Cycle (WLTC).

Research was done in co-operation between Finnish Meteorological institute, Tampere University, and Metropolia University of Applied Sciences. The research and results presented are funded by Business Finland (TAQIITA -project), Helsinki Region Environmental Services authority (HSY), Dekati Oy, Neste Oyj and Pegasor Oy.

Further information:

Hilkka Timonen, Finnish Meteorological Institute, tel. +358 50 380 2864,

Reference: Pirjola, L., Kuuluvainen, H., Timonen, H., Saarikoski, S., Teinilä, K., Salo, L., Datta, A., Simonen, P., Karjalainen, P., Kulmala, K., and Rönkkö, T.: Potential of renewable fuel to reduce diesel exhaust particle emissions, Applied Energy, 254, 113636, 10.1016/j.apenergy.2019.113636, 2019.

Science news archive