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Diesel Sulfur Emissions Calculator - SO2 from ULSD, Off-Road, Heating Oil, or Custom Sulfur Content

Gallons burned and sulfur grade in. SO2 and sulfate PM out, ULSD through high-sulfur.

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Estimate sulfur dioxide (SO2) from diesel or distillate fuel use based on sulfur content in ppm by weight. Enter annual fuel consumption and select ULSD, a nonroad ULSD screen, a legacy 500 ppm comparison, a heating-oil placeholder, or a measured custom sulfur value. The app also shows EIA-based CO2 context and local NOx and PM placeholder factors, but it does not determine permit limits, NSPS compliance, Title V status, or state fuel legality.

Pro Tip: For 50,000 gallons/year, the sulfur mass-balance estimate is about 0.005 tons/year SO2 at 15 ppm and about 0.18 tons/year at 500 ppm. Use that as a quick comparison only. Confirm fuel sulfur from supplier documents or lab data, then use the method required by the permit, state agency, or reporting program.

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How It Works

  1. Select Fuel Grade

    Choose ULSD, the current nonroad ULSD screen, a legacy 500 ppm comparison, a heating-oil placeholder, or enter a custom sulfur value in ppm by weight.

  2. Enter Fuel Consumption

    Input annual fuel use in gallons. The SO2 estimate uses a 7.1 lb/gallon diesel density from EPA AP-42 large stationary diesel context.

  3. Review SO2 Estimate

    See sulfur-derived SO2 in pounds and tons per year. The app assumes sulfur converts to SO2 for screening and does not separately estimate sulfate or condensable PM.

  4. Compare Sulfur Levels

    Use the comparison view to see how 15 ppm, 500 ppm, 2000 ppm, and 5000 ppm sulfur levels change the SO2 estimate for the same fuel use.

  5. Verify Before Reporting

    Check product transfer documents, delivery tickets, lab results, permit method, state rules, and approved emission factors before using any value in a regulated inventory.

Built For

  • Facility managers evaluating the SOx impact of off-road diesel vs ULSD for mobile equipment
  • Environmental staff calculating SO2 for annual emission inventories from diesel equipment
  • Plant engineers determining whether fuel sulfur contributes to major source status
  • Compliance staff preparing a source-check list before a regulated emissions inventory
  • Fleet managers quantifying emission reductions from diesel fuel grade upgrades
  • Air quality consultants modeling sulfur emission reductions for permit modifications

Assumptions

  • Fuel sulfur is entered as ppm by weight.
  • Diesel density is 7.1 lbs/gallon for No. 2 distillate unless otherwise specified.
  • Sulfur-derived SO2 is estimated with the sulfur-to-SO2 mass ratio of 2.
  • CO2 uses the EIA distillate diesel/home-heating fuel coefficient of 22.45 lb/gallon.
  • NOx and PM shown by the app are local screening placeholders, not engine-tier or permit factors.

Limitations

  • Actual fuel sulfur content varies by supplier and batch.
  • Does not decide highway, nonroad, locomotive, marine, heating-oil, waiver, or state fuel legality.
  • Does not model sulfate PM, condensable PM, sulfur capture, ash chemistry, or aftertreatment effects.
  • Does not replace AP-42 review, MOVES, CEMS, source testing, permit factors, or agency-approved inventory methods.
  • Does not determine Title V, PSD, NSR, NSPS, RICE NESHAP, HAP, or state permit applicability.

References

  1. EPA AP-42, Chapter 3.3 - Gasoline and Diesel Industrial Engines.
  2. EPA AP-42, Chapter 3.4 - Large Stationary Diesel and All Stationary Dual-fuel Engines.
  3. EPA Diesel Fuel Standards and 40 CFR Part 1090 fuel designation context.
  4. EIA Carbon Dioxide Emissions Coefficients for diesel and home heating fuel.
  5. ASTM D5453 - Standard Test Method for Determination of Total Sulfur in Petroleum Products.

Frequently Asked Questions

SO2 (lbs) = Fuel consumed (gallons) × Fuel density (lbs/gal) × Sulfur content (weight fraction) × 2. The factor of 2 accounts for the molecular weight ratio of SO2 (64) to S (32) - each pound of sulfur produces 2 pounds of SO2. For ULSD at 15 ppm: 10,000 gallons × 7.1 lbs/gal × 0.000015 × 2 = 2.13 lbs SO2.
ULSD is the 15 ppm sulfur category. EPA describes the highway and nonroad, locomotive, and marine diesel phase-in, but actual fuel use still depends on fuel designation, state rules, waivers, equipment category, and product-transfer documentation.
Heating-oil sulfur is state and supplier specific. Some delivered fuel may also be suitable for ULSD designation, while other heating-oil products may not be. Use the delivered fuel sulfur value, not a generic web value, before estimating SO2.
At the app density basis, 100,000 gallons at 500 ppm sulfur gives about 710 lb, or 0.36 tons, of SO2. At 15 ppm, the same fuel use gives about 21.3 lb, or 0.011 tons. Treat 500 ppm as a comparison or exception case, not a general legality statement.
No. The sulfur calculation estimates SO2/SOx as SO2. Sulfate or condensable PM treatment depends on the inventory method, permit, fuel composition, engine, and control equipment, so this app leaves that as a source gap instead of using an unsupported default fraction.
Disclaimer: This calculator is a preliminary screening estimate. Fuel sulfur content should be verified through supplier documentation, product transfer documents, delivery tickets, or current lab methods. AP-42 factors are averages and should not be used as permit limits or compliance determinations. Consult your state environmental agency or qualified environmental professional before regulated use.

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