Graph of the Day: Drop in Coal use drives U.S. greenhouse reductions

November 3, 2011

Lester Brown/Earth Policy Institute:

Between 2007 and 2011, carbon emissions from coal use in the United States dropped 10 percent. During the same period, emissions from oil use dropped 11 percent. In contrast, carbon emissions from natural gas use increased by 6 percent. The net effect of these trends was that U.S. carbon emissions dropped 7 percent in four years. And this is only the beginning.

The initial fall in coal and oil use was triggered by the economic downturn, but now powerful new forces are reducing the use of both. For coal, the dominant force is the Beyond Coal campaign, an impressive national effort coordinated by the Sierra Club involving hundreds of local groups that oppose coal because of its effects on human health.

Even as coal plants are closing, the use of wind, solar, and geothermally generated electricity is growing fast. Over the last four years, more than 400 wind farms—with a total generating capacity of 27,000 megawatts—have come online, enough to supply 8 million homes with electricity. (See data.) Nearly 300,000 megawatts of proposed wind projects are in the pipeline awaiting access to the grid.

Texas, long the leading oil-producing state, is now the leading generator of electricity from wind. When the transmission lines linking the rich wind resources of west Texas and the Texas panhandle to the large cities in central and eastern Texas are completed, wind electric generation in the state will jump dramatically.

In installed wind-generating capacity, Texas is followed by Iowa, California, Minnesota, and Illinois. In the share of electricity generation in the state coming from wind, Iowa leads at 20 percent.

With electricity generated by solar panels, the United States has some 22,000 megawatts of utility-scale projects in the pipeline. And this does not include residential installations.

Closing coal plants also cuts oil use. With coal use falling, the near 40 percent of freight rail diesel fuel that is used to move coal from mines to power plants will also drop.

In fact, oil use has fallen fast in the United States over the last four years, thus reversing another long-term trend of rising consumption. The reasons for this include a shrinkage in the size of the national fleet, the rising fuel efficiency of new cars, and a reduction in the miles driven per vehicle.

Fleet size peaked at 250 million cars in 2008 just as the number of cars being scrapped eclipsed sales of new cars. Aside from economic conditions, car sales are down because many young people today are much less automobile-oriented than their parents.

In addition, the fuel efficiency of new cars, already rising, will soon increase sharply. The most recent efficiency standards mandate that new cars sold in 2025 use only half as much fuel as those sold in 2010. Thus with each passing year, the U.S. car fleet becomes more fuel-efficient, using less gasoline.

Miles driven per car are declining because of higher gasoline prices, the continuing recession, and the shift to public transit and bicycles. Bicycles are replacing cars as cities create cycling infrastructure by building bike paths, creating dedicated bike lanes, and installing sidewalk parking racks. Many U.S. cities, including Washington, D.C., Chicago, and New York, are introducing bike-sharing programs.

Furthermore, when people retire and no longer commute, miles driven drop by a third to a half. With so many baby boomers now retiring, this too will lower gasoline use.

As plug-in hybrid and all-electric cars come to market, electricity will replace gasoline. An analysis by Professor Michael McElroy of Harvard indicates that running a car on wind-generated electricity could cost the equivalent of 80-cent-a-gallon gasoline.

With emissions from coal burning heading for a free fall as plants are closed, and those from oil use also falling fast—both are falling faster than emissions from natural gas are ramping up—U.S. carbon emissions are falling.

We are now looking at a situation where the 7 percent decline in carbon emissions since the 2007 peak could expand to 20 percent by 2020, and possibly even to 30 percent. If so, the United States could become a world leader in cutting carbon emissions and stabilizing climate.

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