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Utilization of biofuels to vehicles is attracting attention globally from viewpoints of preventing global warming, effectively utilizing the resources, and achieving the local invigoration. Representative examples are bioethanol and biodiesel. This study highlights biodiesel and hydrotreated vegetable oil (HVO) in view of reducing greenhouse gas emission from heavy-duty diesel vehicles. Biodiesel is FAME obtained through ester exchange reaction by adding methanol to oil, such as rapeseed oil, soybean oil, palm oil, etc. As already reported, FAME has fuel properties different from conventional diesel fuel, resulting in about 10% increase in NOx emission [1],[2],[3]. Suppression of such increase in the NOx emission during operating with biodiesel requires adjustment of the combustion control technology, such as fuel injection control and EGR, to the use of biodiesel.

Eco-driving is an environmentally friendly driving manner which improves fuel economy. Since Eco-driving has an immediate and significant effect on improving vehicle's fuel economy, introduction of devices, that main functions are measuring vehicle speed and elapsed time on-board, making alerts when drivers deteriorate fuel economy, and recording driving patterns, is being promoted to support Eco-driving. However, fuel economy improvement rates by Eco-driving show uneven distribution because many factors such as the weather, road and traffic conditions, types of vehicles and drivers' individualities have influence on fuel economy. In this research, correlations between fuel economy improvement and drivers' individualities were examined on a proving ground. Then, in order to estimate the effect of fuel economy by Eco-driving in real traffic conditions, test drives using more than 1,000 trucks were carried out for 5 months with compared to the data of no Eco-driving.

Hybrid trucks have now started to penetrate the Japanese market. To investigate their advantages for fuel economy and exhaust emissions, a real time on-board measurement system for fuel economy and NOx emissions was mounted in a medium duty hybrid truck with a capacitor system. Running tests were carried out with various payloads on roads. The results demonstrated the advantages of the hybrid truck in real traffic conditions. Fuel economy was improved on urban and suburban roads, as compared to a base diesel vehicle. The hybrid truck showed less NOx emissions during acceleration at starting, whereas, acceleration of diesel vehicles may cause intensive localized NOx pollution of roadsides, in places like intersections.

Hybrid trucks are disseminated on the market in Japan. To bring out advantages of fuel economy and low emission, on-board measuring system for fuel consumption and NOx emissions was mounted in a light duty truck with a parallel hybrid system. Tests were carried out with various payloads on roads. As the results, advantages of the tested hybrid truck were shown from the actual data regarding the fuel economy and NOx emissions, considering regeneration energy by the hybrid system. Improvement of the fuel economy and NOx emissions was clearly observed in the running condition such as urban and suburban roads. From the analysis of regeneration energy during vehicle deceleration, it turned out that a longer slowdown time and a higher speed at which deceleration begins result in larger amount of energy regeneration, which means the improvement of fuel economy. For the improvement of roadside pollutions, the reduction of NOx emissions in running using the second gear position is desired.

This paper describes the history of promotional activities in Japan for neat methanol fuel (M100) vehicles. Since the middle of the 1980s, Nippon Methanol Fueled Vehicles Co., Ltd. (now, Organization for the Promotion of Low Emission Vehicles (LEVO)), has been leasing M100 vehicles, and has conducted research work regarding these vehicles. LEVO has also been involved in infrastructure promotion for M100 vehicles, to ensure energy security and as a countermeasure against air pollution. As a result, as of March 1999, a total of 572 M100 vehicles had been leased to fleet operators. This more than 10 years of market experience with these vehicles has contributed toward convincing the Japanese Government, local governments and fleet operators of methanol's potential as an automotive fuel.

Widespread use of biofuels for automobiles would greatly reduce CO2 emissions and increase resource recycling, contributing to global environmental conservation. In fact, activities for expanding the production and utilization of biofuels are already proceeding throughout the world. For diesel vehicles, generally, fatty acid methyl ester (FAME) made from vegetable oils is used as a biodiesel. In recent years, hydrotreated vegetable oil (HVO) has also become increasingly popular. In addition, biomass to liquid (BTL) fuel, which can be made from any kinds of biomass by gasification and Fischer-Tropsch process, is expected to be commercialized in the future. On the other hand, emission regulations in each country have been tightened year by year. In accordance with this, diesel engines have complied with the regulations with advanced technologies such as common-rail fuel injection system, high pressure turbocharger, EGR and aftertreatment system.