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| VMT rose slightly in 2009 while emissions from gasoline and diesel fuel declined, a result EIA attributes as a likely result of more efficient vehicles and increased consumption of biofuels. Click to enlarge. |
Total US greenhouse gas (GHG) emissions were 6,576 million metric tons carbon dioxide equivalent (MMTCO2e) in 2009, a decrease of 5.8% from the 2008 level, according to Emissions of Greenhouse Gases in the United States 2009, a report released by the US Energy Information Administration (EIA).
Since 1990, US GHG emissions have grown at an average annual rate of 0.4%. The results for 2009 represent the largest%age decline in total US GHG emissions since 1990, the starting year for EIA’s data on total GHG emissions. EIA Administrator Richard Newell attributed the decline to the economic downturn, combined with an ongoing trend toward a less energy-intensive economy and a decrease in the carbon-intensity of the energy supply.
Total estimated US GHG emissions in 2009 consisted of 5,446.8 million metric tons of carbon dioxide (82.8% of total emissions); 730.9 MMTCO2e of methane (11.1% of total emissions); 219.6 MMTCO2e of nitrous oxide (3.3% of total emissions); and 178.2 MMTCO2e of hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) (2.7% of total emissions).
Emissions of energy-related carbon dioxide decreased by 7.1% in 2009, having risen at an average annual rate of 0.8% per year from 1990 to 2008. Among the factors that influenced the emissions decrease was a decline in Gross Domestic Product (GDP) of 2.6%. The energy intensity of the US economy, measured as energy consumed per dollar of GDP (Energy/GDP), fell by 2.2% in 2009.
Year-to-year declines in energy intensity are relatively common, EIA noted. There was also a decline in the carbon dioxide intensity of US energy supply (CO2 per unit of energy) in 2009, caused primarily by a drop in the price of natural gas relative to coal that led to more natural gas consumed for the generation of electricity. Also contributing was an increase in renewable energy consumption, led by wind and hydropower.
Methane emissions increased by 0.9%, while nitrous oxide emissions fell by 1.7% in 2009. Based on partial data constituting about 77% of the category, combined emissions of HFCs, PFCs and SF6 increased by 4.9%.
Transportation. The electric power sector accounts for 40% of all energy-related CO2 emissions. The transportation sector is the second-largest source, at 34% of the total. Those emissions are principally from the combustion of motor gasoline, diesel fuel, and jet fuel.
Carbon dioxide emissions from the US transportation sector in 2009 were an estimated 1,854.5 million metric tons—81 million metric tons lower than in 2008 (-4.3%) but still 267 million metric tons higher than in 1990 (+16.8%). The transportation sector has led all US end-use sectors in emissions of carbon dioxide since 1999.
Petroleum combustion is by far the largest source of carbon dioxide emissions in the transportation sector. Increases in the consumption of ethanol fuel in recent years have mitigated the growth in transportation sector emissions. (Reported emissions from energy inputs to ethanol production plants are accounted for in the industrial sector.)
Emissions from gasoline and diesel fuel combustion in the transportation sector generally have paralleled total vehicle miles
traveled since 1990. In 2009, however, vehicles miles traveled rose slightly while combined emissions from gasoline
and diesel fuel declined—likely as a result of more efficient vehicles and increased consumption of biofuels, EIA said.
The transportation sector has dominated the growth in US carbon dioxide emissions since 1990, accounting for 69% of the total increase in US energy-related carbon dioxide emissions.
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