Propane Backgrounder

Renewable Propane may cost $1/gal more than regular propane at $2-3/gal. Most propane is a fossil fuels derived from oil and gas wells.

Residential Propane is mostly bought and sold in liquid form as LPG (Liquefied Propane Gas). Propane is used for heating and transportation.

Wellhead natural gas may contain 0-6% propane. It and other C₃, C₄ an C₅ molecules are removed in oil refineries before natural gas is sold. Since there will be storage, pipelines and tanker trucks involved propane losses might be tricky to establish.

The GWP of propane has been traditionally evaluated at 3 for it's 3 carbon atoms but that's after it has decomposed to CO₂ in the atmosphere. A better number might be as reported in the ACR Journal for R290 (refrigerant grade propane) that quotes a 100 yr GWP of 0.02! Wikipedia reports a GWP of 0.072 (from the IPCC AR6 report).

Propane losses are therefore going to be pretty insignificant compared to other emissions. CO2 emissions from burning the fuel for energy will dominate propane usage.

US EIA reports NM residential Propane sales seem to float around 200 Mgal/d (thousands of US gallons per day) and LPGASMagazine reports 78 million gallons for 2019. Together I then get a range of 0.455-0.487 Mtpa of CO₂ emissions from propane sales in the state.

EDF reported in 2015, O&G methane emissions in NM were 570,000 tons/yr. At a 20 yr GWP of 86 that's about 49 Mtpa CO₂e. We must bear in mind that natural gas production in the NM Permian basin has reportedly increased by a factor of 10 in the past 10 years. So 49 Mtpa is probably a significant underestimate for today. Either way it's over 100 times estimated propane combustion emissions.

Calculations

Propane's chemical formula is C₃H₈ (MW 44) and when burned/oxidized 1 kg will make 3 kg of CO₂ (MW 44).

LPG relative density is about 0.55.

Weight of a US gallon of water = 8.34 lb or 3.785 kg

Weight of EIA's 200 Mgal/d NM propane annual sales, W = 3.785 * 0.55 * 200 * 1,000 * 365 / 1,000 tonnes per annum

Corresponding Weight of CO₂ from 100% propane annual sales burning is 3 * W *44/44 = 0.455 Mtpa (mega-tonnes per annum)

Using the LPGASMag's 78 Mgal/yr one gets a 0.487 Mtpa