Off-site
Marine Traffic Emission Factors
The emission factors adopted are made reference to emission standards as stated in the technical highlights[1] published by the United States Environmental Protection Agency. Table 1 in the EPA’s technical highlights shows the emission standards for Categories 1 and 2 marine diesel engines. According to the Notice of Proposed Rulemarking[2], engines for fishing vessel are belonged to the Category 1 marine diesel engines. Thus, the most conservative values of the emission standards for the Category 1 marine diesel engine as stated in the EPA’s Highlights are adopted as the emission factors for the pollutants in this assessment. The emission standards of different pollutants are shown in Table 1.
Table 1 Emission
Standards for Category 1 Marine Diesel Engines
|
Pollutants |
NOx + HC |
TSP |
CO |
|
Emission Standards
(g/kW-hr) |
7.5 |
0.40 |
5.0 |
With reference to the emission standards for Category 1 Marine Diesel Engines, the emission factors of 0.4g/kW-hr and 5.0g/kW-hr are adopted for PM and CO respectively. It is noted that the emission standard of 7.5g/kW-hr is for NOx + HC. However, the emission factor of 7.5g/kW-hr for NOx is adopted for conservative approach. It is assumed that 20% of NOx would be converted to NO2.
Off-site Marine Traffic Emission Rates
The emission rates in the unit of g/s of the pollutants from the fishing vessels depend on the horsepower of the vessels’ engines and fractional load (the actual engine output divided by rated engine output). Since it is considered that fishing vessels travelling within the typhoon shelter in slow cruise mode is the worst case scenario for marine vessels emissions, the load factor of 40% (refer to a technical report on Commercial Marine Vessels Emissions published by the United States Environmental Protection Agency[3]) is adopted for the assessment. Based on the information of the engine data of the fishing vessels provided by the Marine Department, the average horsepower of the fishing vessels and sampans were estimated to be 814hp and 203hp respectively. The estimated emission rates for different pollutants are estimated based on the equation below and shown in Table 2.
Emission Rate=(Emission Factor(g/kW-hr)xHorsepower
(hp)x0.746kW/hpxFractional Load)/3600
Table 2 Emission
Rates of Off-site Marine Traffic
|
Pollutants |
Types of vessels |
Horsepower, hp |
Fractional Load |
Emission Rates, g/s |
|
TSP |
Fishing Vessel |
814 |
0.4 |
0.0270 |
|
Sampan |
203 |
0.4 |
0.0067 |
|
|
NO2 |
Fishing Vessel |
814 |
0.4 |
0.1012 |
|
Sampan |
203 |
0.4 |
0.0252 |
|
|
CO |
Fishing Vessel |
814 |
0.4 |
0.3372 |
|
Sampan |
203 |
0.4 |
0.0841 |
[1] United States Environmental Protection Agency, Emission Standards for Marine Diesel Engines: Scope of Application, February 200
[2] United States Environmental Protection Agency, Control of Emissions of Air Pollution from New Compression Ignition Marine Engines at or above 37kW, December 1998.
[3] United States Environmental Protection Agency, Analysis of Commercial Marine Vessels Emissions and Fuel Consumption Data, February 2000