Exhaust Gas Emissions from Heavy-Duty Engines and Passenger Cars with Different After-Treatment Systems Running on Hydrotreated Vegetable Oil (HVO) 2014-01-2827

One political and economic aim in Europe is to increase the use of renewable energy resources. In the transport sector, up to 10 % of fossil diesel fuel should be replaced by biogenic fuels by 2020. This also means a reduction in crude oil dependency. In the area of diesel fuel, fatty acid methyl esters are introduced since over 20 years as biodiesel. However, biodiesel can lead to an increase of engine oil dilution in passenger cars with diesel particulate filters. During the regeneration of the particulate filters, there is an entry of fuel components in the engine oil. While most of the diesel fuel (DF) evaporates from the engine oil, biodiesel remains in the oil and can cause sludge formation in the engine. A promising approach to reduce this problem is the use of a new type of biogenic fuel, called hydrotreated vegetable oil (HVO). This is also produced from vegetable oil or animal fat. Like biodiesel, HVO is free of sulfur and any aromatics. HVO has a higher cetane number in comparison with biodiesel and most diesel fuels.

The impact on regulated and non-regulated emissions of HVO was tested using two heavy-duty engines as well as on a fleet of eleven passenger cars of the emission standards Euro 3 to Euro 6. The cars and engines were equipped with different exhaust gas after-treatment systems. As reference for the biogenic fuels CRC reference diesel fuels were used.

In the heavy-duty engine tests, less emissions of regulated components were found for HVO compared to reference diesel fuel.

But for passenger cars, that positive emission trend could not be verified because an increase of nitrogen oxides emission in the range of 5 % to 14 % was recorded. Also, the exhaust gases of HVO showed less mutagenic effects than diesel fuel tested by salmonellae cultures.