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Gas vs Propane Emissions Calculator - Side-by-Side CO2, NOx & SOx Comparison

Compare the environmental footprint of natural gas and propane for heating, process, and power generation

Compare local natural gas and propane CO2, NOx, and SOx rows side by side. Enter annual therms, annual propane gallons, and AFUE to see gross heat input, delivered heat, annual screening totals, and CO2 per delivered MMBtu. The screen uses source-aware warnings because NOx, SOx, permit methods, source-test data, CEMS data, controls, and fuel analysis still control regulated emissions.

Pro Tip: EIA lists natural gas at 116.65 lb CO2/MMBtu and propane at 138.63 lb CO2/MMBtu. That supports a CO2 screen, not a permit factor package. NOx and SOx still depend on burner design, fuel sulfur, controls, source category, and the method your permit or reporting program requires.

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Natural Gas vs Propane Emissions Calculator
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How It Works

  1. Enter Annual Fuel Use

    Input annual natural gas use in therms and annual propane use in gallons. The screen reports the emissions for those entered values, not a permit-ready inventory.

  2. Set AFUE Values

    Enter equipment efficiency so delivered MMBtu and CO2 per delivered MMBtu can be screened. AFUE does not change the gross emissions from fuel already consumed.

  3. Review Local Rows

    Compare local CO2, NOx, and SOx rows per gross MMBtu. CO2 is tied to EIA source pointers; NOx and SOx remain source gaps until reconciled to the exact source.

  4. Read Source Warnings

    Check the visible warnings for AP-42, GHGRP, permit, supplier heat-content, source-test, CEMS, fuel-sulfur, and qualified-review gaps.

  5. Resolve Site-Specific Factors

    For regulated or investment use, verify current EPA factors, permit terms, fuel records, equipment data, controls, and environmental review before acting.

Built For

  • Facility managers screening local fuel-use records before a deeper emissions review
  • Environmental staff checking rough natural gas and propane CO2 differences before source-factor reconciliation
  • Rural facilities documenting that propane and natural gas comparisons need supplier and equipment data
  • Corporate sustainability teams separating simple CO2 arithmetic from reporting-factor selection
  • Engineers comparing delivered heat context before utility, equipment, and permit review
  • Energy consultants building an early question list for a qualified emissions calculation

Assumptions

  • Natural gas is entered in therms and propane is entered in gallons.
  • CO2 rows follow EIA source pointers for current CO2 coefficients.
  • NOx and SOx rows are local placeholders until the exact source category and method are reconciled.
  • AFUE is used for delivered-heat context only.
  • Regulated use requires current source factors, records, and qualified review.

Limitations

  • Does not include PM, CO, VOC, HAP, CH4, N2O, controls, startup, shutdown, or malfunction emissions.
  • Does not choose an AP-42 table row, GHGRP factor, permit factor, source-test method, or CEMS method.
  • Does not include upstream or lifecycle emissions from extraction, processing, delivery, storage, or leakage.
  • Does not model fuel price, conversion cost, infrastructure cost, supply reliability, or equipment derating.
  • Does not determine permit modification, Title V, PSD, NSR, state inventory, or reporting obligations.

References

  • EIA Carbon Dioxide Emissions Coefficients by Fuel.
  • EIA Methodology for Carbon Dioxide Emissions Coefficients.
  • EPA AP-42 Chapter 1 external combustion source page.
  • EPA GHG Emission Factors Hub and 40 CFR Part 98 Subpart C source pointers.

Frequently Asked Questions

The current EIA source pointer lists natural gas at 116.65 lb CO2/MMBtu and propane at 138.63 lb CO2/MMBtu. On that basis, natural gas is lower per gross MMBtu. Delivered-heat comparison still depends on actual equipment efficiency.
Do not treat this screen as a final NOx answer. NOx depends on source category, burner design, firing rate, load, low-NOx controls, combustion tuning, source-test data, CEMS records, and permit method.
No. The app currently screens CO2, NOx, and SOx only. PM, CO, VOC, HAP, CH4, N2O, and CO2e inventory work need the current reporting method and source-specific factors.
The app uses 1 therm of natural gas as 100,000 BTU and a local propane row of 91,500 BTU per gallon. Use supplier heat content or program-specific values when reporting or making a purchase decision.
It can, but this app does not determine permit applicability or modifications. Review permit terms, approved fuels, source category, emissions increases, state rules, and permitting authority instructions before changing fuels.
Disclaimer: Planning screen only. CO2 rows use EIA source pointers, while NOx and SOx remain local source-gap rows. The output is not an AP-42 table reproduction, GHGRP filing, permit calculation, source-test method, CEMS method, lifecycle model, or fuel-switching economic analysis.

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