The U.S. Energy Information Administration (EIA) released an analysis that looks at the level and drivers of energy-related carbon dioxide (CO2) emissions in 2009. A key finding shows that energy-related CO2 emissions in the U.S. fell by 7 percent or 405 million metric tons -- the largest drop since the start of EIA's record of annual energy data more than 60 years ago. EIA attributes the huge drop partly to the economic downturn.
Here are some key findings.
The four biggest factors that caused the drop in 2009 emissions are population, per capita GDP, energy intensity of the economy, and carbon intensity of the energy supply. All of these fell in 2009 except for population, which grew 0.9 percent. The report shows that energy intensity and the carbon intensity of the energy supply both fell more than 2 percent, and when combined with a lower GDP, resulted in the 7 percent reduction in emissions.
The report indicates that total energy consumption fell across all end-use sectors by 4.8 percent, impacting the industrial sector the most, which saw a 9.9 percent drop in energy consumption.
The recent decline in industrial energy use reflects the impact of the downturn in the economy, which has disproportionately impacted energy-intensive industries. Another factor, says the EIA, is a continued long-term trend of growth in the service sector compared to the industrial industry.
In addition, decreased consumption of carbon-emitting fossil fuels across all sectors resulted in lower carbon intensity and lower absolute emissions. Emissions from coal dropped 12.0 percent, petroleum emissions were down 5.3 percent and natural gas emissions were down 1.6 percent. However, non-fossil fuel consumption increased about 2 percent.
The report also finds that new and efficient natural gas generators have played a large role in lowering the carbon intensity of the electric power sector. From 2000 to 2008, about 120 gigawatts of natural gas combined cycle generation capacity were added.
In 2000, electric power sector generation from natural gas was 518 billion kWh, leading to emissions of 281 million metric tons carbon dioxide. By 2009, generation had risen to 841 billion kWh and emissions were 374 million metric tons. As a result, the emissions intensity fell from 0.542 to 0.445 metric tons per thousand kWh, or by 18 percent. This means the new generation capacity prevented the emissions of 82 million metric tons of carbon dioxide.
Wind energy also played a role. Increased wind-based generation since 2000 prevented 39 million metric tons of emissions in 2009 relative to electricity supplied at the average emissions rate, according to the report. Wind generation increased by 15,000 million kilowatt hours in 2009.
EIA projects if energy-intensive industries lead the economic recovery, emissions will increase faster than if service industries or light manufacturing play the leading role. If coal, which was more heavily impacted by the recent economic downturn than other energy sources, rebounds disproportionately, the carbon intensity of the energy supply could rise above the 2009 level.
EIA projects that CO2 emissions will rise 1.3 percent in 2011, based partly on increased use of coal in the utility sector, and continued economic growth that will lead to a rebound in travel-related petroleum consumption.
