Petroleum resources being exhausted, global warming by carbon dioxide and air pollution in urban areas by nitrogen oxides are getting serious these days. These problems are closely related with the automobile industry. Of the total energy consumption in Japan, 24% is consumed in the transportation sector and its some 90% is by automobiles.Accordingly, the sector accounts for 19% of the total carbon dioxide emission. As for nitrogen oxides, as much as 53%of the total emission is attributable to automobiles in some districts. In this situation, the automobile industry has been making active efforts to develop low-pollution vehicles improved in fuel consumption and emission. Main efforts are directed to CNG (Compressed Natural Gas) vehicles, methanol vehicles, electric vehicles, hybrid electric vehicles, etc. CNG vehicles can somewhat reduce COz and NOx, but fuel tanks are heavy, one-charge travel distance is short and the fuel supply infrastructure is not so easy to establish. Methanol vehicles generate much COz in the process of fuel production and, similar to CNG vehicles,are not easy to construct the fuel supply infrastructure.Electric vehicles, including hybrid ones, have begun to be developed actively. But electric vehicies are inferior in one-charge travel distance and carrying capacity although emissions can be eliminated at all. It is not practical to develop electric trucks. Meanwhile, hybrid electric vehicles can secure travel distance and carrying capacity.
Features of Hybrid electric vehicles:
Energy Production Eficiency.In Japan, since this vehicle is included in the G Wcl ass of more than 2.5 tons, emission gas measurement is carried out in operation of the engine alone. Therefore, although the drive mode on actual vehicle is not specified by the emission gas measurement regulation, M15 mode was used in our evaluation. This is the clrive mode in a city for trucks.
Vehicle EfficiencyThe motor is driven by the power saved in the battery. When the vehicle is braked, the battery is charged by converting the braking energy to electric power.Because the energy source of each vehicle varies, the fuel consumption is compared with calorific value base.
Total Eficiency:The total energy efficiency, fiiel consumption, CO2 emission and NOx emission of each vehicle are cadculated by taking into account the eEciency and gas emissions during fuel production.