Emissions Benefits of Replacing Conventional Diesel with CNG in Buses
| Fuel | CO | NOX | PM |
| Diesel | 2.4 g/km | 21 g/km | 0.38 g/km |
| CNG | 0.4 g/km | 8.9 g/km | 0.012 g/km |
| % reduction |
84 | 58 | 97 |
Note : Medium-duty diesel buses, central business district test cycle, CO carbon monoxide; NOx oxides of nitrogen; PM particulate matter; g/km grams per kilometer.
Emissions from Selected Two-stroke Three-wheelers in Bangladesh
(grams per kilometer)
(grams per kilometer)
| Vehicle age | Lubricant type | Percentage lubricant | Hydrocarbons | Carbon monoxide | Oxides of nitrogen | Particulate matter |
| 7 years | Straight | 8% | 23 | 25 | 0.03 | 2.7 |
| 7 years | 2T | 3% | 16 | 17 | 0.09 | 0.9 |
| 4 years |
Straight | 8% | 9 | 8 | 0.08 | 0.6 |
| 4 years | 2T | 3% | 9 | 10 | 0.09 | 0.2 |
Note : a. Data taken after performing simple maintenance procedures on the vehicle
Source : ARAI (Automotive Research Association of India), November 2000.
These measurements are preliminary and require further analysis.
From : Kojima et al, “Improving Urban…………….Engine Vehicles”, South Asia Environment Unit, The World Bank, Dec.2000
What are the issues We see ?
Ambient air quality has shown improvement due to :
- Fuel quality, Fuel change, industrial fuel use, industrial siting policies, etc.
- Other not quantified factors such as more cleaner technology vehicles of road, cleaner domestic fuels, Efficient combustion technologies
- Poor Air Monitoring System, Manual errors, Instrumental errors, Lack of QA/QC ?????????
How Some Methods adopted today do not help in understanding AQ Issues
Emission Inventory
Weight based EIPercentage based EI w/o knowledge of all sources
Overall EI, no application of height of emission
Toxicity ??
Exposure ??
Contributions to Ambient Air
Meteorology
Major Issue besides the above: Incomplete knowledge of all sources
Why certain sectors contribution appears higher?
Weight based computationPerception based
Sources not known
Estimates not available
Knowledge of Sources in India
Very poor information on background PM concentrations (Particularly fine PM)IF CONTRIBUTIONS OF FINE PM ARE NOT VEHICLES, IT WILL BE FUTILE TO CONTROL ONE SECTOR TOO MUCH
SOURCE APPORTIONMENT STUDIES VERY FEW AND FOR LIMITED AREAS
HIGH VARIATIONS IN OVREALL PM PERCENTAGE IS LIKELYRealistic Expectations Researcher
Complete understanding of all the sources within the city, region, country and elsewhereCarry out programmes which also support the expectations of the local/national policy maker (CNG/Diesel ??)
Effective validated models for forecasting and continuous upgraded system