Where Do US Carbon Emissions Come From?

Have you ever wondered just what activities cause our fossil fuel carbon emissions, and how much emission is caused by which activities? Well, Lawrence Livermore National Laboratories (LLNL) has produced the chart above to tell us exactly that for the USA economy. Although we are now far into 2016, LLNL has not yet produced a carbon chart for 2015. This chart for 2014 is the most recent one we have.

carbon_2014_united-states

If you need to see a larger version, you can download the original png file from https://flowcharts.llnl.gov/commodities/carbon.

Our carbon emissions (actually, carbon dioxide, but called “carbon” on the chart) do not change much from year to year, unless the whole economy takes a hit – recession or depression. Even then the change has been only a few percentage points. Emission levels from 2014 are still useful information.

The numbers on the chart indicate the millions of metric tons (MMT) of carbon emissions coming from each component in the chart. (Each metric ton weighs 2200 pounds, or 10% more than the “ton” in the English system of weights and measures.) The thickness of the lines is scaled proportionately to the MMT of emissions.

Thus, electricity generation accounts for 2040 MMT, about 38% of the total 5410 MMT of emissions. Of this 2040, 0.4 came from geothermal , 444 from natural gas, 1560 from coal and 36.9 from petroleum. As the fine print says, these numbers do not exactly add up to 2040. They add up to exactly 2041.3, which has been rounded off to 2040.

Of course, electricity is actually used by the residential, commercial, industrial and transportation sectors of the economy. Residential uses 37.6% of electricity production; commercial, 36.4%; industrial, 25.7%; and finally, transportation, only 0.23%. This information also comes from LLNL (https://flowcharts.llnl.gov/). Thus it is reasonable to allocate emissions from electrical production to the parts of the economy that use the electricity.

Residential use accounts for 341 MMT of direct emissions. 276 comes from natural gas and 64.9 from petroleum. In less technical terms, the natural gas goes into gas furnaces and water heaters. The petroleum goes into heating oil for a different sort of furnace. To this we should add another 767 MMT (37.6% of electricity’s 2040 MMT), for a grand total of 1108 MMT, or just over 20% of 5410.

Direct commercial use accounts for 232 MMT, mostly from natural gas. Adding in the 743 MMT from commercial use of electricity, we have 975 MMT, or around 18% of total carbon emissions.

Industrial use contributes 962 MMT; 479 from natural gas, 141 from coal and 342 from petroleum. Industrial’s 25.7% of electricity production will add 574 MMT; 1536 in all, about 28% of all emissions.

The largest producer of emissions is transportation, even though it accounts for a miniscule 0.23% of electricity consumption. The 1830 MMT from direct burning of petroleum and some natural gas would make it the largest even before the additional 5 MMT from electricity consumption is counted. Transportation – cars, trucks, ships, trains and airplanes – accounts for 34% of all US carbon emissions.

To summarize:
Transportation – 34%, little electricity.
Industrial – 28%, 1/3 from electricity.
Residential – 20%, 2/3 from electricity.
Commercial – 18%, 3/4 from electricity.

That’s where the carbon emissions come from. What to do about it? That’s a long, long discussion which has to start with knowing which of our economic activities produce how much carbon emissions.

This does not cover carbon emissions from land use changes, or global warming emissions from leaking methane or cattle production. It’s just an accounting of fossil fuel use and carbon emissions from fossil fuels. It’s far from the entire story for global warming/climate change, but it is the essential central story for emissions from the US industrial economy.

(This article also appears in the 2016 edition of SEMG’s publication The Activist.)

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Author: Art Myatt

Retired engineer and environmentally aware activist with Green Party of Michigan, Sierra Club and Alliance to Halt Fermi 3.

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