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Biodiesel Fuel (BDF) Research Work Group works on identifying technological issues on the use of high biodiesel blends (over 5 mass%) in conventional diesel vehicles under the Japan Auto-Oil Program started in 2007. The Work Group conducts an analytical study on the issues to develop measures to be taken by fuel products and vehicle manufacturers, and to produce new technological findings that could contribute to the study of its introduction in Japan, including establishment of a national fuel quality standard covering high biodiesel blends. For evaluation of the impacts of high biodiesel blends on performance of diesel particulate filter system, a wide variety of biodiesel blendstocks were prepared, ranging from some kinds of fatty acid methyl esters (FAME) to another type of BDF such as hydrotreated biodiesel (HBD). Evaluation was mainly conducted on blend levels of 20% and 50%, but also conducted on 10% blends and neat FAME in some tests.

Diesel emissions are significant issue worldwide, and emissions requirements have become so tough that. the application of after-treatment systems is now indispensable in many countries To meet even more stringent future emissions requirements, it has become apparent that the improvement of market fuel quality is essential as well as the development in engine and exhaust after-treatment technology. Japan Clean Air Program II (JCAP II) is being conducted to assess the direction of future technologies through the evaluation of current automobile and fuel technologies and consequently to realize near zero emissions and carbon dioxide (CO2) emission reduction. In this program, effects of fuel properties on the performance of diesel engines and a vehicle equipped with two types of diesel NOx emission after-treatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined.

Compared with diesel fuel, FAME is relatively unstable and readily generates acids such as acetic acid and propionic acid. When FAME-blended diesel fuel is used in existing diesel vehicles, it is important to maintain the concentration of FAME-origin acid in the fuel at an appropriately low level to assure vehicle safety. In the present study, the oxidation of diesel fuel containing 5% FAME is investigated. Several kinds of FAMEs were examined, including reagents such as methyl linoleate and methyl linolenate, as well as commercially available products. The level of acid, peroxide, water, and methanol and the pressure of the testing vessel were measured. The result shows that unsaturated FAMEs that have two or more double bonds are unstable. Also, water is generated by oxidation of FAME blended diesel fuel, accelerating corrosion of the terne sheet.

In the Japan Clean Air Program II (JCAP II) Diesel WG, effects of fuel properties on the performance of two types of diesel NOx emission aftertreatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined. For a Urea-SCR system, the NOx emission reduction performance with and without an oxidation catalyst installed in front of the SCR catalyst at low exhaust gas temperature operation was compared. For an NSR catalyst system, the effect of fuel sulfur on both emissions and fuel economy during 50,000 km driving was examined. Furthermore, effects of other fuel properties such as distillation on exhaust emissions were investigated. The results show that sulfur is the influential factor for both devices. Namely, high NOx emission reduction performance of the Urea-SCR system with the oxidation catalyst at low exhaust gas temperature operation is influenced by sulfur.

The Agency of Natural Resources and Energy, Ministry of Economy, Trade and Industry has conducted conformity tests of diesel fuel containing Fatty Acid Methyl Ester (FAME) to amend diesel fuel standards in Japan. The objective of the tests is to examine appropriate specifications of diesel fuel containing FAME for automotive use for existing vehicles in the Japanese market. The conformity testing includes verification of fuel system component compatibility, tail pipe emissions, and characterization of the reliability and durability of the engine system, including the fuel injection system. In designing the conformity tests, the maximum FAME concentration was 5%. Most of the new standards are essentially equivalent to EN14214, but the total acid number (TAN) of specific acids, and oxidation stability of the new standards for diesel fuel containing FAME, are different from EN14214.

Ultra-low energy consumption and ultra-low emission vehicle technologies have been developed by combining petroleum-alternative clean energy with a hybrid electric vehicle (HEV) system. Their component technologies cover a wide range of vehicle types, such as passenger cars, delivery trucks, and city buses, adsorbed natural gas (ANG), compressed natural gas (CNG), and dimethyl ether (DME) as fuels, series (S-HEV) and series/parallel (SP-HEV) for hybrid types, and as energy storage systems (ESSs), flywheel batteries (FWBs), capacitors, and lithium-ion (Li-ion) batteries. Evaluation tests confirmed that the energy consumption of the developed vehicles is 1/2 of that of conventional diesel vehicles, and the exhaust emission levels are comparable to Japan's ultra-low emission vehicle (J-ULEV) level.

In 1999, some Japanese fuel suppliers sold highly concentrated alcohol fuels, which are mixtures of gasoline and oxygenates, such as alcohol or ether, in amounts of 50% or more. In August 2001, it was reported that some vehicle models using the highly concentrated alcohol fuels encountered fuel leakage and vehicle fires due to corrosion of the aluminum used for the fuel-system parts. The Ministry of Economy, Trade and Industry (METI) and the Ministry of Land, Infrastructure and Transport Government of Japan (MLIT) jointly established the committee on safety for highly concentrated alcohol fuels in September 2001. The committee consisted of automotive technology and metal corrosion experts knowledgeable about preventing such accidents and ensuring user safety. Immersion tests were conducted on metals and other materials used for the fuel-supply system parts to determine the corrosion resistance to each alcohol component contained in the highly concentrated alcohol fuels.

Fuels of wide range of density and viscosity were tested by using a DI diesel engine that conforms to present Japanese regulations. A total of 9 fuels was tested. Six test fuels were commercial automotive diesel fuel available in Japan. In order to expand the density range, test fuels of kerosene, high-density diesel fuel and automotive diesel fuel in Singapore were also included. The density range was 0.796 to 0.856 (g/cm3), and the viscosity range was 1.52 to 5.44 (mm2/s). The test mode was Japanese D13. Also, some fuels were tested by the Japanese transient test mode. Moreover, fuel spray was observed by an optical method to clarify the relationship between viscosity and Sauter mean diameter.

To achieve high-accuracy measurements of fuel consumption in testing on natural gas vehicles, a method for measuring the absolute value of fuel consumption by the gravimetric method using certificated reference weights and an electric platform scale has been developed. By performing a flow-meter test and a chassis dynamometer test using the gravimetric method, the measurement accuracy of the value of fuel flow rate and fuel consumption obtained by the fuel flow meters, carbon balance method, and air-to-fuel ratio method was evaluated. As a result, a highly accurate method for measuring fuel consumption in chassis dynamometer tests has been confirmed.