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The target of the European Union (EU) from the 1990s has been to reduce the level of greenhouse gas (GHG) in the climate by 40 % by 2030 [1]. Currently the transport sector is one of the biggest greenhouse gas emission producer in the EU [2]. Drop-in biofuels can contribute to the reduction of GHG emissions in the transport sector. Diesel R33, a newly developed biofuel enables sustainable mobility fulfilling the European diesel fuel specification and reduces the GHG emissions by about 18.2 % against fossil diesel fuel. Diesel R33 is made of 7 % used cooking oil methyl ester, 26 % hydrotreated vegetable oil (HVO) and 67 % high quality diesel fuel. HVO was produced from rapeseed and palm oil. This new biofuel was tested in a fleet of 280 vehicles (passenger cars, light duty vehicles, off-road vehicles and urban buses) covering all emission classes. The impact of the new fuel on the vehicles, their emissions and the engine oil aging was investigated.

Increasing the proportion of renewable energy in the transport sector and therefore the reduction of the dependence on fossil oil is a prime political and economic goal in Europe and also in many other parts of the world. In the diesel sector, especially vegetable oil methyl ester is introduced. The blending of commercial diesel fuel with up to 7 % of biodiesel leads to a lot of problems in the range of engine oil in cars. Because of the regeneration of diesel particle filter, there is an increase entry of unburnt fuel into the engine oil. The first effect of this fuel entry is the engine oil dilution which can be observed for all diesel fuels. Unlike biodiesel, commercial diesel fuel can mostly evaporate out of the engine oil because of its boiling range between 165 °C and 360 °C (73 % of the fuel has a boiling point under 320 °C). The boiling range of fossil diesel fuel was measured in preparation of this study.

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.

The European diesel fuel specification limits the biodiesel content to 7 %. It is, however, desirable to increase the amount of renewables in the transport sector; therefore blending with a higher biogenic fuel content is of interest. Blending of fuels can lead to chemical reactions between fuel components and may result in undesired products. In detail, aged biodiesel from unsaturated FAME and fossil diesel fuels can form oligomers and precipitations with a maximum in the range of B10 to B20. Precursors are oligomers that can be separated from the biodiesel or the blends in an amount of up to 20 %. These oligomers are soluble in the fuel, but they seem to have potency for chemical reactions with fuel components or the engine oil. To prevent tentative problems in the fuel filter, the injecting system and the combustion process itself, the formation of oligomers should be disabled in blends. Alcohols have been proven and tested to dissolve precipitations in the fuel.

A 500 hours endurance test was performed with a heavy-duty engine (Euro IV); MAN type D 0836 LFL 51 equipped with a PM-Kat®. As fuel 100% biodiesel was used that met the European specification EN 14214. The 500 hours endurance test included both the European stationary and transient cycle (ESC and ETC) as well as longer stationary phases. During the test, regulated emissions (carbon monoxide, nitrogen oxides, hydrocarbons and particulate matter), the particle number distribution and the aldehydes emission were continuously measured. For comparison, tests with fossil diesel fuel were performed before and after the endurance test. During the endurance test, the engine was failure-free for 500 hours with the biogenic fuel. There were almost no differences in specific fuel consumption during the test, but the average exhaust gas temperature increased by about 15°C over the time. Emissions changed only slightly during the test.

Diesel engines are expected to remain in use for high power applications even with the rising fuel prices and environmental concern and the new laws imposed by government to reduce emissions. Unfortunately, diesel engines possess a bad reputation of producing higher PM and NOx emissions compared to gasoline engines. The present work describes the use of different additives to diesel or biodiesel fuel to reduce NOx emissions up to 22 % from the diesel and up to 47 % from the biodiesel fuels. This study is a preliminary investigation of the successful reduction of NO x emissions from diesel and from biodiesel fuels and forwards a strong argument that SNCR could reduce the NO x emissions from diesel engines in an efficient way when proper compounds are chosen to do the work.

Rapeseed oil methyl ester, two common fuels and one artificial blend were investigated their effects on particulate emissions. A heavy-duty diesel engine equipped with a diesel oxidation catalyst (DOC) was used for this test. Properties such as composition of particulate matter, as well as particle size and number distributions were measured using an electronic low pressure impactor (ELPI) and a scanning mobility particle sizer (SMPS) besides the regulated emissions: carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM). Furthermore investigations were carried out regarding the influence of dilution temperature on particle number distribution measured via SMPS. Studies were carried out with and without a DOC. Additionally the mutagenic potency of the particulate and gaseous emissions was determined using the Ames test. RME led to lower regulated emissions than common diesel fuel with exception of NOx.

The replacement of petrol derived fuels by biogenic fuels from renewable resources has become of worldwide interest and is scientifically investigated for its environmental costs and benefits. Biodiesel has been proven as a suitable alternative to fossil diesel fuel and blends up to 20% biodiesel with common diesel fuel are a strongly pushed policy in the U.S.A. and the EU. To investigate the influence of blends on the emissions and possible health effects, we performed a series of studies with several engines (Euro 0, III and IV) measuring regulated and non-regulated exhaust compounds and determining their mutagenic effects using the Bacterial Reverse Mutation Assay (Ames-Test) according to OECD Guideline 471. Emissions of blends showed an approximate linear dependence on the blend composition, in particular when regulated emissions are considered. However, a negative effect of blends was observed with respect to mutagenicity of the exhaust gas emissions.

Diesel engine emissions (DEE) are classified as probably carcinogenic to humans. Since 1995 we observed an appreciable reduction of mutagenicity of DEE driven by reformulated or newly designed fuels in several studies. We compared the mutagenic effects of DEE from two different batches of rapeseed oil (RSO) with rapeseed methyl ester (RME, biodiesel), natural gas derived synthetic fuel (gas-to-liquid, GTL), and a reference diesel fuel (DF). Additionally, we determined the regulated emissions of total hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOX), and particulate matter (PM). Compared with the reference DF the two RSO qualities significantly increased the mutagenic effects of the particle extracts by factors of 9.7 up to 59. RME extracts had a moderate but significant higher mutagenic response. GTL samples did not differ significantly from DF.

Two batches of rapeseed oil methyl esters containing approximately 10 ppm phosphorus (RME10), one rapeseed oil methyl ester with a content of less than 1 ppm phosphorus (RME) and common diesel fuel (DF) were investigated regarding their effects on regulated and non-regulated emissions of a modern diesel engine (Euro IV) equipped with an SCR system (selective catalytical reduction of nitrogen oxides). The regulated emissions of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and particulate matter (PM) were determined for RME10 and DF. Non-regulated emissions alkenes, alkynes, aromatics, aldehydes, ketones and the particle size distribution were measured for all fuels. Additionally the mutagenic potency of the PM emissions was determined using the Ames test. RME10 led to lower regulated emissions than conventional diesel fuel. Regarding the non-regulated emissions RME showed the lowest values compared with RME10 and DF.

Different fuels, in detail: three blends from methyl esters of rapeseed oil, soy bean oil, and palm oil; neat rapeseed oil methyl ester; a gas-to-liquid fuel (GTL); and two new diesel fuel qualities from Aral and Shell (Ultimate and V-Power, respectively) were compared to reference diesel fuel (DF) with focus on emissions. Therefore, the regulated emissions carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and particulate matter (PM) and the non regulated particle size distribution were determined. Additionally to the emissions the mutagenic potency of conventional reference diesel fuel, biodiesel, Shell V-Power Diesel, and Aral Ultimate Diesel was tested. With the exception of CO, GTL always led to better results of regulated emissions than conventional diesel fuel (DF). Except for NOx, biodiesel emitted less regulated compounds than GTL and all diesel fuels. Biodiesel showed the lowest mutagenicity.

The more stringent regulations for diesel engine emissions lead to the requirement that both fuels and engines must be developed jointly. In the future, so-called designer fuels will help to achieve the stringent limits. In our research, conventional diesel fuel, biodiesel, Swedish low sulfur diesel fuel MK1 and a specially designed diesel fuel were compared using a DaimlerChrysler diesel engine, running the modes of the ECE 49 test cycle. The results for regulated and non-regulated gaseous emissions, particulate matter size distributions as well as mutagenic effects of particle extracts are reported.