By Kevin Wilcox
U.S. energy consumption increased in 2014, but heavier reliance on natural gas and wind resulted in a muted increase in carbon emissions.
The development of such sources as wind and natural gas has enabled the United States to increase its energy usage while decreasing its carbon emissions, according to a new analysis. Wikimedia Commons/Energy.gov
June 9, 2015—The U.S. used more total energy in 2014 than in any year since the Great Recession, but a shifting mix of sources for that energy meant that carbon emissions were down from 2010 levels, according to a study and flow chartreleased recently by the Lawrence Livermore National Laboratory (LLNL), in Livermore, California, and the U.S. Department of Energy.
The United States consumed an estimated 98.3 quadrillion BTU, or quads, of energy in 2014—up from 97.4 quads in 2013 and 95.1 quads in 2012. Carbon emissions in 2014 were 5,410 million metric tons (mmt), which is up from 5,390 mmt in 2013, but down from 2010, when the nation consumed 98 quads of energy—similar to its 2014 consumption—and carbon emissions were 5,632 mmt.
A.J. Simon, LLNL's energy group leader, says that this reduction in carbon emissions can be attributed to a combination of the emergence of wind energy and a greater acceptance of natural gas for electricity generation and industrial applications. "It's mostly wind—and a little solar—that accounts for maybe one-third to a half of the emission reductions that we've seen," says Simon, who notes that although solar is growing much more quickly, there is far more wind energy online. Solar energy has grown dramatically in the past five years, from 0.11 quads in 2010 to 0.427 quads in 2014. At the same time, wind energy grew from 0.92 to 1.73 quads.
"The other big [factor] is that the low price of natural gas has encouraged a lot of power producers to move away from burning coal to generate electricity [to using] natural gas to generate electricity. Natural gas, in the best of scenarios, releases about half the amount of carbon dioxide as coal when used to produce electricity," Simon notes.
Between 2010 and 2014, the energy produced by coal declined from 20.82 quads to 17.9 quads. The energy produced from natural gas increased from 24.65 to 27.5. Simon notes that the emergence of hydraulic fracturing of shale to retrieve natural gas has "given pretty much everyone in the economy confidence that gas prices here in the U.S. will stay relatively low and relatively stable. Gas is actually an easier fuel to managing in your power plant and it is cleaner. It hedges against environmental risk better than coal does."
The use of energy sourced from petroleum, which is used primarily in transportation and industrial applications, has fluctuated over the past five years but is currently down from 35.97 quads in 2010 to 34.8 quads in 2014. The majority of that decline is in the transportation sector. "One of the things you saw during the recession was people were driving a lot less," Simon says. "Just around that same time, a lot of more-efficient vehicles came to market. While the entire vehicle fleet hasn't turned over yet, a lot of the new cars sold over the past five or ten years are significantly more efficient than the cars that were being sold the decade before. You're beginning to see that reflected in reduced or flat petroleum use with the growing economy."
One of the biggest energy stories of 2014—the sharp decline in oil prices—occurred too late in the year to be fully reflected in the current chart. So if low prices prompted American consumers to travel more or purchase larger, less fuel-efficient vehicles in the closing months of 2014, those changes would not be reflected in the current findings, Simon says, Instead, they will ripple through the 2015 chart.
Last year was "actually a very interesting year in energy," Simon says. "These charts are a snapshot in time of energy use, and energy use responds to, and also drives, a lot of other things that are going on in the economy."
Overall, the chart presents a picture of a complex energy market in the United States, which relies on nine primary sources of energy. The flow charts from most developed countries show similar diversity of energy sources, albeit with far different proportions. For instance, in France nuclear sources provide10 times more energy than coal.
Although the proportions derived from various sources in the United States are changing, Simon notes that the abundant number of sources is likely to remain intact. "It's always better to have multiple options to perform a given task," he notes. "That makes your system more resilient to changes. It gives you an economic hedging opportunity. And to some extent it gives us the best ability we have to use energy that is fit to the task. We can design a more efficient energy system."