Propane is a Pain

Evan Mills, Ph.D.
2 min readApr 11, 2024

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Years ago, when fossil fuels were used in far greater abundance to make electricity than today, it could be argued that propane was “greener”. With the near death of coal on the grid in many parts of the world and the rapid increase in renewables such as wind and solar, this is no longer the cast.

Under today’s conditions in the U.S., propane tends to be substantially polluting electricity (this varies by state) and even more polluting than burning natural gas, e.g. for heating. It’s also more expensive for consumers. To deliver a consistent amount of heat to a home, propane emits 19% more carbon dioxide than natural gas, costing 86% more. Compared to a highly efficient electric heat pump, propane emits 540% more, costing 127% more. When powering that heat pump with rooftop solar under good conditions, the cost of propane is 390% more and the carbon footprint is of course completely eliminated.

Here’s the analysis visually.

Values are per million BTUs of heat delivered by a home’s heating system to the living area, which accounts for differences in efficiency for the various fuels. Energy prices and emissions per fuel are US averages. Furnace efficiencies are the minimum required under current standards; heat pumps (which don’t have standards) are average. Fuel data from the US Energy Information Administration. Analysis by the author.

Businesses using propane will have similar results.

Notes and Assumptions:

Results for oil, gas, and propane furnaces are worse in the South, where standards are set at 80% efficiency, versus 90% in the North. https://appliance-standards.org/product/furnaces

Central value for COPs for residential heat pump is 3.5. Range of values here: https://www.google.com/url?sa=i&url=http%3A%2F%2Fpublications.energyresearch.ucf.edu%2Fwp-content%2Fuploads%2F2018%2F06%2FFSEC-PF-413-04.pdf&psig=AOvVaw04YxlrximEqCUEsN5MXQcR&ust=1712477373096000&source=images&cd=vfe&opi=89978449&ved=0CBQQjhxqFwoTCICAssKRrYUDFQAAAAAdAAAAABAE

Converson factors for fuel energy content: https://www.eia.gov/energyexplained/units-and-calculators/ and https://www.eia.gov/energyexplained/units-and-calculators/british-thermal-units.php

Average US residential gas prices: https://www.eia.gov/dnav/ng/ng_pri_sum_a_EPG0_PRS_DMcf_a.htm

Average US residential heating oil: https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=W_EPD2F_PRS_NUS_DPG&f=W

Average US residential propane price: https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=W_EPLLPA_PRS_NUS_DPG&f=W

Average US residential electricity price https://www.eia.gov/electricity/data/browser/#/topic/7?agg=0,1&geo=g&endsec=vg&linechart=ELEC.PRICE.US-ALL.A~ELEC.PRICE.US-RES.A~ELEC.PRICE.US-COM.A~ELEC.PRICE.US-IND.A&columnchart=ELEC.PRICE.US-ALL.A~ELEC.PRICE.US-RES.A~ELEC.PRICE.US-COM.A~ELEC.PRICE.US-IND.A&map=ELEC.PRICE.US-ALL.A&freq=A&ctype=linechart&ltype=pin&rtype=s&pin=&rse=0&maptype=0

Average US rooftop solar price (levelized capital cost — best conditions, after incentives): https://www.pv-magazine.com/2023/04/14/average-solar-lcoe-increases-for-first-time-this-year/

Average US heating coal price from Lowes ($9.98 for a 40-pound sack)

Average US electricity emissions factor: https://www.eia.gov/tools/faqs/faq.php?id=74&t=11

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Evan Mills, Ph.D.

Energy & environment scientist, with 40 years experience developing and advancing climate change solutions. http://evanmills.lbl.gov