The bus is a very efficient mode of public transport, which is cheap, flexible and, in many cases, tailored to the needs of end-customers both in terms of capacity and speed. From an economic, environmental and social point of view, the bus still remains the most universal solution for a balanced and sustainable urban development. Some 80% of all public transport passengers worldwide are carried by buses.
Buses are responsible for 8% of carbon monoxide emissions (CO), 6% of hydrocarbons (HC), 9% of nitrogen oxide emissions (NOx), 7.7% of particulates (PM) and 5% of carbon dioxide (CO2). The release of CO2 into the atmosphere occurs whenever fossil fuel is burned and contributes to the greenhouse effect and global warming.
The fundamental problem in limiting emissions of heavy-duty diesel engines is to simultaneously decrease both NOx and particulates. Classic diesel technology has seen in the last years massive improvements by EU emission (Euro 1-5) standards. Permanent changes of these standards, striving for higher energy efficiency, and pressure for using clean and renewable energy sources, imposed a competitive development of alternative fuels and technologies for powering modern vehicles
A wide range of non oil-based options for road transport has been developed in the last decade, and some technologies are already commercialized. However, it is currently impossible to predict which technologies will emerge as the front-runners for the future city bus propulsion. Five technological mainstreams are discussed today: Biofuels, Natural Gas and LPG, Hybrids, Hydrogen and fuel cells and Battery Electric Vehicles.
The cleanest bus technologies available on the market today are CNG, Diesel euro V, DE hybrid, electric vehicles. While CNG and Diesel euro V appear to be the most ripe, and DE-hybrid seem to be the most promising both for the emission levels and the energy efficiency performance, electric vehicles have a more limited range. Finally, the very few hydrogen fuel cell powered vehicles circulate mainly, when not exclusively, as prototypes.
On the basis of investigations of the state in the area of clean technologies and their perspectives, carried out in one of European projects, it was concluded that the compressed natural gas (CNG) and hybrid are two technologies to be addressed for a joined procurement of clean buses.
The paper reviews a comparative analysis of CNG and DE hybrid buses to conventional diesel buses on the basis of the collected and analyzed data from different literature sources which are then presented as a survey. The analysis includes capital and operation costs during life cycles of different bus samples considered from different points of view. In addition, special attention has been paid to the emission and
energy characteristics of the considered buses.
The paper also contains a comparative analysis of the fuel and emission costs, caried out by a European bus manufacturer, based on the Direct...
Saobraćajna sredstva i transport