SO 2 Emission Factors Kristin Burford 23/April/01 ME 449A: Sustainable Air Quality Source: Environmental News ServiceEnvironmental News Service

Table of Contents n Purpose and Methods n EPA Emission Preparation n Major Sources of SO 2 – Coal Combustion – Oil Combustion – Gas Combustion – Petroleum Refining – Non-Road Diesel n Trends of SO 2 Emissions n Summary and Recommendations

Purpose and Methods n Determine how the SO 2 emissions were calculated by the EPA – Find out general emission calculation information – Determine major sources of SO 2 according to 1996 Trends DataTrends Data – Explore the specific factors which influence the the SO 2 emissions for the major sources

EPA Emission Preparation n How are emissions determined? – Two factors: source information and emission factors General Equation : Emission = Emission Factor*Quality of Consumed Fuel n emission factors found in AP-42AP-42 n qualities of consumed fuel include amount of fuel, energy produced, % of precursor element in the fuel n In this study, the focus is on emission factors and how they are calculated – EPA rates the emission factors from A (best) to E according to how well the calculated emission correlates with the actual emission

Major Sources of SO 2 (1996) The major sources of SO 2 emissions include: Fuel Combustion Coal Oil Gas Industrial Processes Petroleum Refining Transportation Non-Road Diesel For more detailed information on the SO 2 sources, consult EPA SO 2 trends data for 1996 EPA SO 2 trends data for 1996

Coal Combustion Emission Factors n 60-70% of SO 2 Emissions n Coal Rank: – anthracite - more C, less volatile, rare – bituminous - less C & more volatile than anthracite, most common – sub-bituminous - lower S, more volatile & moisture than bituminous n Uncontrolled emission factors (lbs SO 2 /ton coal): Uncontrolled emission factors – 38*%S - bituminousRating: A – 35*%S - sub-bituminousRating: A – 39*%S - anthraciteRating: B n Have shown good correlation between calculated and actual emissions

Oil Combustion n 10-20% of total SO 2 emissions n Uncontrolled emission factor (lbs SO 2 /10 3 gal): Uncontrolled emission factor 0.98(MW SO2 /MW S )(%S/100)x oil density x 1000 (oil gallons) Rating: A n Variables and Assumptions: – 98% conversion assumed – %S – MW – oil density n assumed 7 for distillate and 8 for residual n actual range (distillate) (residual)

Gas Combustion n 5-10% of total SO 2 emissions n Uncontrolled emission factor: Uncontrolled emission factor (S grains/100 ft 3 )(lb/7000 grains)(ft 3 /1000 gal)(2 lb SO 2 /lb S) = 0.6 lbs SO 2 /10 6 std. ft 3 (scft) gas Rating: A n Assumes 100% conversion of fuel S to SO 2 and 2000 grains of S/10 6 scft. n Can convert emission factor to energy units using the average heating value of the gas (good approximation?) n Actual emissions not measured, therefore accuracy of emission factor is difficult to determine n Conservative, assume all S --> SO 2

Petroleum Refining n 1-5% of total SO 2 emissions n No background on emission factor calculation in AP-42 n Refining includes converting crude oil to over 2500 different products n Multiple Processes – Separation – Conversion – Treating – Feedstock and product handling – Auxiliary processes n The emission factors in the AP-42 have large ranges, probably depending on the product purity desiredemission factors

Non-Road Diesel n 1-5% of total SO 2 emissions n Data indicates that non-road diesel has a much larger contribution than any other transportation source n Not included in AP-42 online – EPA has limited information on emissions of non-road sourcesnon-road sources – Emissions based on : travel & rate of emission – SO 2 based on 0.25% S in fuel (can be adjusted) n EPA recently decided to reduce the amount of sulfur in diesel fuels, however this will only effect road sources (see Federal Register for more information)Federal Register

Trends of SO 2 Emissions Total SO 2 emission & Coal SO 2 emission have virtually the same trend Other sources did not have a great impact on the total SO 2 emissions (see other trend plots)trend plots

Summary and Recommendations n Summary: – Generally, the emission factors for combustion are accurate. – Petroleum refining and non-road diesel sources emission factors are not clearly defined n Recommendations: – Further work should be done on controls for the combustion sources – Improve accuracy of emission factors for other sources which significantly contribute to total SO 2 emissions – Consider regulating sulfur in non-road diesel fuels