Energy-Related Carbon Dioxide Emissions

Although total U.S. energy-related CO2 emissions increased by almost 4 percent in 2010, they do not return to their 2005 level (5,996 million metric tons) by the end of the AEO2012 projection period (see Figure 4 on page 2). Emissions per capita fall by an average of 1 percent per year from 2005 to 2035, as growth in demand for transportation fuels is moderated by higher energy prices and Federal CAFE standards. In addition, electricity-related emissions are tempered by efficiency standards, State RPS requirements, and implementation of the CSAPR, which helps shift the fuel mix away from coal toward lower carbon fuels.

Energy-related CO2 emissions reflect the mix of fossil fuels consumed. Given the high carbon content of coal and its use to generate 45 percent of the U.S. electricity supply in 2010, prospects for CO2 emissions depend, in part, on growth in electricity demand as well as the portion of that demand satisfied by coal-fired generation. After declining from 2007 to 2009, electricity sales grew in 2010 by 4.3 percent. Electricity sales continue to grow through 2035 in the AEO2012 Reference case, but the growth is tempered by a variety of regulatory and socioeconomic factors, including appliance and building efficiency standards and a continued transition to a more service-oriented economy. The combination of slow demand growth, competitive natural gas prices, and CSAPR included in the AEO2012 Reference case lowers the consumption of coal within the first 5 years of the projection period; as a result, emissions from coal combustion in the power sector in 2015 are 149 million metric tons below the AEO2011 Reference case projection. With modest growth in electricity demand and increased use of renewables for electricity generation, electricity-related CO2 emissions grow by a total of 4.9 percent (0.2 percent per year) from 2010 to 2035. Growth in
CO2 emissions from transportation activity also slows in comparison with the recent pre-recession experience, as Federal CAFE standards increase the efficiency of the vehicle fleet, employment recovers slowly, and higher fuel prices moderate growth in travel. The AEO2012 Reference case projections do not include proposed increases in fuel economy standards for model years 2017 through 2025, which are expected to further reduce fuel use and emissions.

Taken together, these factors tend to slow the growth in primary energy consumption and CO2 emissions. As a result, energyrelated CO2 emissions in 2035 are only 3 percent higher than in 2010 (as compared with the 10-percent increase in total energy use), and the carbon intensity of U.S. energy consumption falls from 57.4 to 53.8 kilograms per million Btu (6.3 percent). Over the same period, U.S. economic activity becomes less carbon-intensive, as energy-related CO2 emissions per dollar of GDP decline by 45 percent.