Understanding Carbon Intensity

Written on: August 31, 2023

Renewable propane has a lower carbon impact than other energy sources.

Everyone agrees that climate change is a genuine existential threat to our planet, and we must adjust our energy usage to reduce greenhouse gas emissions. Conventional propane has long been an eco-friendly alternative fuel that powers heats, powers home appliances and commercial equipment, fuels road vehicles and serves many other vital functions.

Even so, the propane industry is working tirelessly to find ways to lower its product’s environmental impact. Renewable propane gas (rPG) is one of the most promising decarbonizing tools in development and limited use today. But how do you quantify a fuel’s emissions impact? The most useful measurement is carbon intensity.

What is carbon intensity?

Carbon intensity (CI) is a convenient measure to determine how much of an emissions impact our energy has. Essentially, it indicates how many grams of carbon dioxide (CO2) are generated to produce a given amount of energy. We typically express units as grams of carbon dioxide equivalent (CO2 released) per Megajoule (energy produced). You might see this represented as gCO2eq/MJ. This measurement is used by California’s Low Carbon Fuel Standard, among others, and it allows us to compare multiple fuels. For reference, the CI score of conventional propane is 79.

Carbon intensity is also a useful measurement because it accounts for CO2 released into our atmosphere over the life cycle of an energy source, including generation and distribution — not just at one point in the process.

What is the CI of grid electricity?

Advocates of total electrification argue that mandating electric heating, appliances and vehicles will lower home emissions. But this ignores the environmental impact of generating grid electricity. The average U.S. grid’s CI rating is 130. That said, different states’ grids have variable CIs. West Virginia and Wyoming rely heavily on coal and other fossil fuels for their electricity and have CIs approaching 300.

Even a state like New York (CI rating: 59) with a relatively clean power grid must fall back on natural gas, petroleum and other fossil fuels when demand spikes.

electricity carbon footprint

Map source: https://propane.com/about-propane/renewable-propane/

Now, look at the CI ratings of several renewable propane (rPG) products.

CI of renewable propane

By creating a fuel that is molecularly identical to conventional propane from organic and recycled feedstocks, rPG producers significantly lower the overall CI rating. While all rPG products boast a CI far lower than U.S. grid electricity, fuel oil, gasoline and diesel, how low it is depends on the feedstock involved.

According to the California Air Resources Board, rPG made with domestic, non-rendered, used cooking oil has a carbon intensity score of 20.5.

CI of camelina-based rPG

Renewable propane producers are working tirelessly to identify and develop renewable feedstocks that ensure a lower carbon impact. One of the most appealing prospects right now is camelina, an oilseed crop with similar properties to canola. Camelina grows on dry, fallow land, requires little water, matures quickly and is naturally resistant to pests and diseases.

Even better, camelina can become livestock feed after oil is extracted. California-based Global Clean Energy estimates that, with this “meal credit,” renewable fuel made from camelina can have a CI score of 7!

CI of propane blends with renewable DME

Renewable dimethyl ether (rDME) is a biogas with similar properties to butane and propane. The raw materials that produce rDME are plentiful, including landfill and farm waste. Because you can store, transport and burn rDME like you do propane, it can blend with conventional propane and rPG.

And rDME can significantly lower the CI of propane. The question is what the optimal blend ratio is. With rDME-blending trials in the U.S., Sweden, Japan and the United Kingdom, there is hope that we could soon see a drop-in propane blend with a CI at or below zero!

propane carbon footprint usa

Map source: https://propane.com/about-propane/renewable-propane/

The Renewable Propane Alliance provides regular updates on advances in the renewable energy sector. Don’t forget to bookmark this site — and feel free to contact us with any questions.

Sources: The Propane Education & Research Council, Global Clean Energy, World LPG Association, Oberon Fuels