Coal-to-Gas Switch Causes CO2 to Drop
17 August 2012
By Kevin Begos / The Associated Press
In a surprising turnaround, the amount of carbon dioxide released
into the atmosphere in the United States has fallen dramatically
to its lowest level in 20 years -- and government officials say
the biggest reason is that cheap and plentiful natural gas has led
many power plant operators to switch from dirtier-burning coal.
Many of the world's leading climate scientists didn't see the drop
coming, in large part because it happened as a result of market
forces rather than direct government action against carbon
dioxide, a greenhouse gas that traps heat in the atmosphere.
Michael Mann, director of Penn State University's Earth System
Science Center, said the shift from coal is reason for "cautious
optimism" about potential ways to deal with climate change. He
said it demonstrates "ultimately people follow their wallets" on
In a little-noticed technical report, the U.S. Energy Information
Agency, a part of the Energy Department, this month said
energy-related U.S. CO2 emissions for the first four months of
this year fell to about 1992 levels. Energy emissions make up
about 98 percent of the total.
The Associated Press contacted environmental experts, scientists
and utility companies and learned that virtually everyone believes
that the shift could have major long-term implications for U.S.
While conservation efforts, the lagging economy and greater use of
renewable energy are factors in the CO2 decline, the drop-off is
due mainly to low-priced natural gas, the agency said.
A frenzy of shale gas drilling in the Northeast's Marcellus Shale
and in Texas, Arkansas and Louisiana has caused the wholesale
price of natural gas to plummet from $7 or $8 per unit to about $3
over the past four years, making it cheaper to burn than coal for
a given amount of energy produced. Utilities are relying more than
ever on gas-fired generating plants.
Both government and industry experts said the biggest surprise is
how quickly the electric industry turned from coal. In 2005, coal
was used to produce about half of all electricity generated in the
United States. The Energy Information Agency said that fell to 34
percent in March, the lowest level since it began keeping records
nearly 40 years ago.
Coal and energy use are still growing rapidly in other countries,
particularly China, and CO2 levels globally are rising, not
falling. Moreover, marketplace changes -- a boom in the economy, a
fall in coal prices, a rise in natural gas -- could stall or even
reverse the shift. For example, U.S. emissions fell in 2008 and
2009, then rose in 2010 before falling again last year.
Also, while natural gas burns cleaner than coal, it still emits
some CO2. Drilling has environmental consequences, which are not
yet fully understood.
The International Energy Agency said the United States has cut
carbon dioxide emissions more than any other nation over the last
six years. Total U.S. carbon emissions from energy consumption
peaked at about 6 billion metric tons in 2007. Projections for
this year are around 5.2 billion, and the 1990 figure was about 5
China's emissions were estimated to be about 9 billion tons in
2011, accounting for about 29 percent of the global total. The
United States accounted for about 16 percent.
Mr. Mann called it "ironic" that the coal-to-gas shift has helped
bring the United States closer to meeting some greenhouse gas
targets in the 1997 Kyoto treaty on global warming, which the
United States never ratified. On the other hand, methane leaks
from natural gas wells could be pushing the United States over the
Kyoto target for that gas.
Even with such questions, public health experts welcome the shift,
since it is reducing air pollution.
"The trend is good. We like it. We are pleased that we're shifting
away from one of the dirtiest sources to one that's much cleaner,"
said American Lung Association spokeswoman Janice Nolen. "It's
been a real surprise to see this kind of shift. We certainly
didn't predict it."
Power plants that burn coal produce more than 90 times as much
sulfur dioxide, five times as much nitrogen oxide and twice as
much carbon dioxide as those that run on natural gas, according to
the Government Accountability Office, the investigative arm of
Congress. Sulfur dioxide causes acid rain, and nitrogen oxides
lead to smog.
Bentek, a Colorado energy consulting firm, said sulfur dioxide
emissions at larger power plants in 28 Eastern, Midwestern and
Southern states fell 34 percent over the past two years, and
nitrous oxide fell 16 percent. Natural gas has helped the power
industry meet federal air pollution standards earlier than
anticipated, Bentek said.
Last year, the Environmental Protection Agency issued its first
rules to limit CO2 emissions from power plants, but the standards
don't take effect until 2014 and 2015. Experts had predicted that
the rules might reduce emissions over the long term, but they
didn't expect so many utilities to shift to gas so early. And they
think price was the reason.
"A lot of our units are running much more gas than they ever have
in the past," said Melissa McHenry, spokeswoman for Ohio-based
American Electric Power Co. "It really is a reflection of what's
happened with shale gas. In the near term, all that you're going
to build is a natural gas plant," she said.
But she warned: "Natural gas has been very volatile historically.
Whether shale gas has really changed that, the jury is still out.
I don't think we know yet."
Jason Hayes, spokesman for the American Coal Council, based in
Washington, predicted that cheap gas won't last.
"Coal is going to be here for a long time. Our export markets are
growing. Demand is going up around the world. Even if we decide
not to use it, everybody else wants it," Mr. Hayes said.
He also said the industry expects new coal-fired power plants to
be built as pollution-control technology advances: "The industry
will meet the challenge" of the EPA regulations.