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Power Sector Carbon Dioxide Emissions Fall Below Transportation Sector Emissions

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, US Energy Information Administration

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  • Jan 20, 2017
graph of energy sector carbon dioxide emissions, as explained in the article text

Source: U.S. Energy Information Administration, Monthly Energy Review


U.S. carbon dioxide (CO2) emissions from the transportation sector reached 1,893 million metric tons (MMmt) from October 2015 through September 2016, exceeding electric power sector CO2 emissions of 1,803 MMmt over the same time period. On a 12-month rolling total basis, electric power sector CO2 emissions are now regularly below transportation sector CO2 emissions for the first time since the late 1970s. CO2 emissions from electric power have been trending lower since 2007.

Comparing emissions over a 12-month period reduces the effects of seasonal fluctuations. Both sectors tend to have higher consumption and emissions in the summer months when electricity demand and vehicle travel are relatively high. Emissions levels through September 2016 represent the latest available data in EIA’s Monthly Energy Review.

The electric power sector makes up a larger share of total U.S. energy consumption than the transportation sector. However, CO2 emissions from the electric power sector are now lower than those from transportation because the carbon intensity of the power sector has fallen much faster than the carbon intensity of the transportation sector.

graph of energy consumption and intensity, as explained in the article text

Source: U.S. Energy Information Administration, Monthly Energy Review


Emissions from the electric power sector are primarily from coal-fired and natural gas-fired electric generators. On average, emissions associated with combusting coal are higher than those associated with combusting natural gas. The average rate of CO2 emitted from combusting coal ranges from 206 to 229 pounds per million British thermal units (lbs CO2/MMBtu), depending on the type of coal consumed. The combustion of natural gas emits on average 117 lbs CO2/MMBtu. Natural gas electric generators also tend to be more efficient than coal generators, because they require less fuel to generate electricity.

In the 12 months from October 2015 through September 2016, coal and natural gas had nearly equal shares of electric power generation in the United States: 31% and 34%, respectively. However, their shares of electric power sector emissions were 61% and 31%, respectively, as coal is much more carbon-intensive. Overall electric power carbon intensity has also decreased as generation share of non-carbon-emitting fuels such as nuclear, hydropower, wind, and solar has grown.

Emissions from the transportation sector are primarily from motor gasoline, distillate fuel oil, and jet fuel, which have carbon intensities lower than coal but higher than natural gas. For example, gasoline emits an average of 157 lbs of CO2/MMBtu. In the 12 months from October 2015 through September 2016, motor gasoline represented 60% of the total emissions from the transportation sector, while 23% was from distillate fuel oil and 12% was from jet fuel.

Very little electricity is used in the transportation sector. Attributing transportation’s share of electric power sector emissions to the transportation sector would only add 4 MMmt CO2 to the transportation sector’s total of 1,893 from October 2015 through September 2016.

graph of sector carbon dioxide emissions by fuel type, as explained in the article text

Source: U.S. Energy Information Administration, Monthly Energy Review


Principal contributors: Cara Marcy, Bill Sanchez

Original Post

Josh Nilsen's picture
Josh Nilsen on Jan 21, 2017

RIP coal, you will not be missed.

The internal combustion engine and steam based power generation are next.

Classical thermal based power generation will be over by 2035.

You can try to beat the economics of semi-conductors, but you won’t.

Nathan Wilson's picture
Nathan Wilson on Jan 22, 2017

I guess you’ve not been following the Hawaiian attempts to move away from fossil electricity; they are encountering difficulties.

Electricity from Hawaiian utility solar PV (with Federal and state subsidies) is soon expected to be cheaper than from burning oil. So when regulators told the power company (HECO) to put together a plan for reaching 100% renewable electricity by 2045, they were shocked to find out that it will make their bills go up (even though the latest plan assumes all homeowner will generate enough annual PV power to offset their use).

Being the only tropical location in the US, and given that renewables there need only compete with imported oil, Hawaii should be the biggest solar success story anywhere. But instead Hawaii is revealing the expensive problems that come with high penetration renewables.

As the following graph shows, they’ll post-pone most of the expensive batteries, biodiesel, and much of the solar until the last few years (when the state portfolio standard jumps from 80% to 100% renewable). Also, they want to temporarily deploy LNG to replace oil and coal.

The latest report doesn’t discuss rate plans much, but the 2014 report indicated that under the proposed “DG-2.0 rate plan”, consumers should not expect a large decrease in monthly electric bills when they add PV to offset all of their power usage.

Nathan Wilson's picture
Nathan Wilson on Jan 22, 2017

Here’s another graph from the Hawaiian 2016 Power Supply Improvement Plan. The graphs comes from simulations done by a consulting firm. It helps show why adding more cheap renewable energy makes the total power bill go up.

As time passes and renewable penetration goes up, there is a rise in renewable cost due to the need for adding batteries; but there is also a large rise in the cost of thermal (backup generation). Some of the rise is due to fuel switching (coal, to oil, to LNG, to biodiesel), and some is apparently due to reduced capacity factors.

Darius Bentvels's picture
Darius Bentvels on Jan 22, 2017

Thanks for the graphs. Can you also publish the link to the report.

I like to see it as those graphs do not fit at all with the results of studies by French govt institute ADEME, neither with those of German think-tank Agora.
So I suspect the authors (HECO?) manipulated conditions such that they got the outcome they wish.

Darius Bentvels's picture
Darius Bentvels on Jan 24, 2017

It explains the deviant results.
HECO continues to defend its business…

Though now in a more smart way than they deed in the past.
Then they refused to connect rooftop solar, using rubbish excuses.

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