Abstract

In recent years, societal concern regarding the exhaust emissions from motor vehicles has intensified. Diesel exhaust pollutants have become a particular concern, with the identification of constituent contaminants classified as human carcinogens in 2012 by the U.S. Environmental Protection Agency (EPA) and the UN World Health Organization’s (WHO) International Agency for Research on Cancer (IARC). Moreover, nitrogen dioxide (NO2) concentration seems to be one of the key problems threatening air quality in cities.

Although numerous debates have arisen in the face of the real-world emission properties of diesel vehicles, transport still represents a major source of PM and NOx, with emission inventory database in Seoul Metropolitan Area, as shown Clean Air Policy Support System (CAPSS). Hence, policy options have been developed for the emission properties of on-road diesel vehicles that can meet SMA’s ongoing regulations regarding exhaust-emission-reduction compliance. Converting diesel city buses to compressed natural gas (CNG) would be one way of reducing PM and NOx emissions in compliance with SMA. Such a policy has been developed, and implemented for diesel-fuel city buses.

However, consideration was not given to city buses along the routes in-and-out of the Seoul administrative district. City buses along these routes seem to be an additional factor to worsen air quality in the SMA due both to operation of old diesel vehicles as well as long-distance trips. To make the Seoul Metropolitan Area’s air cleaner and more breathable for all citizens, dynamic and flexible policy options for converting diesel city buses to CNG will be essential.

When evaluating the choice of city buses, there are many factors to consider, both economic as well as environmental, such as efficiency, air quality, and climate change. This study focuses only on the environmental considerations. Then, as for the choices of converting diesel city buses to CNG, only environmental performance need be compared. The purpose of this research is then to encourage the mutual benefit of PM·NOx emission reduction from city buses operated on routes in-and-out of the administrative district in the SMA. The PM10, PM2.5 and NOx emission contributions within the boundary of Seoul due to Inchon city buses along the routes in-and-out administrative district constitute 0.13ton/year, 0.12ton/year, and 63.4ton/year, respectively. Correspondingly, the PM10, PM2.5 and NOx emissions within the Seoul boundary due to city buses from Gyeonggi Province are 2.4ton/year, 2.2ton/year, and 503.7ton/year, respectively. These figures are substantial evidence for making air clean and sustainable through the cooperation of local governments with the government in the SMA.

The following policy options are therefore recommended to facilitate the reduction of excessive PM and NOx emissions from on-road diesel city buses; 1) Make converting diesel to CNG for city buses sustainable via financial aid, possibly by covering the price gap between diesel and CNG bus; 2) Support a bus retrofit program by flexibly upgrading excessively emitting city buses to less emitting ones or new CNG buses; 3) Re-adjust the diesel-fuel discharging fee by levying PM and NOx pollutants, and allowing distribution of these funds to programs promoting CNG buses in SMA; 4) Enforce stringent emission testing programs to measure reduction of PM and NOx emissions, and follow-up management monitored functionally during the inspection and checkup of on-road diesel city buses; 5) Implement an integrated PM and NOx emission management system for city bus operating companies along the routes in-and-out of the administrative district; 6) Introduce a new PM and NOx emission grading system for diesel buses, thereby encouraging clean buses to be well operated; 7) Install more CNG stations, thereby encouraging use of CNG buses; 8) Build a park-and-ride system for bus routes in-and-out of the administrative district to discourage automobile use; 9) Introduce new evaluation systems to enable the accelerated retirement of old diesel bus and their conversion to clean CNG buses, in case of deciding new in-and-out administrative district routes; and 10) Establish a realistic and effective consensus-based governance system for reducing PM and NOx emission from old diesel city buses; and Finally to make the above recommendations easier to implement, ‘role definition’ would be identified for sustainable clean air in SMA. 


Contents

01 Introduction
1_Background and Purpose
2_Research Framework
 
02 The Dimensions of Diesel City Buses in SMA
1_Registration of City Buses
2_Operation Condition of City Buses
 
03 PM·NOx Emission Calculation from City Buses
1_Emission Inventories of Mobile Source
2_Calculation of PM·NOx Emissions from City Buses
 
04 Policy Issues on PM and NOx Emission of City Buses in SMA
1_Incentive System Policy on CNG Buses Conversion
2_Low Emission Policy on City Buses in SMA
3_Implications
 
05 Case Study on Emission Management of Foreign City Buses
1_Cases Study on Emission Management
2_Implications
 
06 Win-Win Approach for PM and NOx Emission Reduction in SMA
1_Requirements of Win-Win Approach Consideration
2_Enforce-based Approach
3_Route Decision-based Approach
4_System-based Approach
 
References
Appendices