Climate Benefits of Natural Gas May Be Overstated
ProPublica
25 January 2011
By Abrahm Lustgarten
The United States is poised to bet its energy future on natural gas as
a clean, plentiful fuel that can supplant coal and oil. But new
research by the Environmental Protection Agency—and a growing
understanding of the pollution associated with the full “life cycle” of
gas production—is casting doubt on the assumption that gas offers a
quick and easy solution to climate change.
Advocates for natural gas routinely assert that it produces 50 percent
less greenhouse gases than coal and is a significant step toward a
greener energy future. But those assumptions are based on emissions
from the tailpipe or smokestack and don’t account for the methane and
other pollution emitted when gas is extracted and piped to power plants
and other customers.
The EPA’s new analysis doubles its previous estimates for the amount of
methane gas that leaks from loose pipe fittings and is vented from gas
wells, drastically changing the picture of the nation’s emissions that
the agency painted as recently as April.
Calculations for some gas-field emissions jumped by several hundred
percent. Methane levels from the hydraulic fracturing of shale gas were
9,000 times higher than previously reported.
When all these emissions are counted, gas may be as little as 25
percent cleaner than coal, or perhaps even less.
Even accounting for the new analysis, natural gas—which also emits less
toxic and particulate pollution—offers a significant environmental
advantage. But the narrower the margins get, the weaker the political
arguments become and the more power utilities flinch at investing
billions to switch to a fuel that may someday lose the government’s
long-term support.
Understanding exactly how much greenhouse gas pollution comes from
drilling is especially important, because the Obama administration has
signaled that gas production may be an island of common political
ground in its never-ending march toward an energy bill. The
administration and Congress are seeking not just a steady, independent
supply of energy, but a fast and drastic reduction in the greenhouse
gases associated with climate change.
Billions of cubic feet of climate-changing greenhouse gases—roughly the
equivalent of the annual emissions from 35 million automobiles—seep
from loose pipe valves or are vented intentionally from gas production
facilities into the atmosphere each year, according to the EPA. Gas
drilling emissions alone account for at least one-fifth of human-caused
methane in the world’s atmosphere, the World Bank estimates, and as
more natural gas is drilled, the EPA expects these emissions to
increase dramatically.
When scientists evaluate the greenhouse gas emissions of energy sources
over their full lifecycle and incorporate the methane emitted during
production, the advantage of natural gas holds true only when it is
burned in more modern and efficient plants.But roughly half of the
1,600 gas-fired power plants in the United States operate at the lowest
end of the efficiency spectrum.
And even before the EPA sharply revised its data, these plants were
only 32 percent cleaner than coal, according to a lifecycle analysis by
Paulina Jaramillo, an energy expert and associate professor of
engineering and public policy at Carnegie Mellon University.
Now that the EPA has doubled its emissions estimates, the advantages
are slimmer still. Based on the new numbers, the median gas-powered
plant in the United States is just 40 percent cleaner than coal,
according to calculations ProPublica made based on Jaramillo’s
formulas. Those 800 inefficient plants offer only a 25 percent
improvement.
Other scientists say the pollution gap between gas and coal could
shrink even more. That’s in part because the primary pollutant from
natural gas, methane, is far more potent than other greenhouse gases,
and scientists are still trying to understand its effect on the
climate—and because it continues to be difficult to measure exactly how
much methane is being emitted.
In November the EPA announced new greenhouse gas reporting rules for
the oil and gas industry. For the first time under the Clean Air Act,
the nation’s guiding air quality law, thousands of small facilities
will have to be counted in the pollution reporting inventory, a change
that might also lead to higher measurements.
The natural gas industry, in the meantime, has pressed hard for
subsidies and guarantees that would establish gas as an indispensible
source of American energy and create a market for the vast new gas
reserves discovered in recent years. The industry would like to see new
power plants built to run on gas, automobile infrastructure developed
to support gas vehicles and a slew of other ambitious plans that would
commit the United States to a reliance on gas for decades to come.
But if it turns out that natural gas offers a more modest improvement
over coal and oil, as the new EPA data begin to suggest, then billions
of dollars of taxpayer and industry investment in new infrastructure,
drilling and planning could be spent for limited gain.
“The problem is you build a gas plant for 40 years. That's a long
bridge,” said James Rogers, CEO of Duke Energy, one of the nation’s
largest power companies. Duke generates more than half of its
electricity from coal, but Rogers has also been a vocal proponent of
cap-and-trade legislation to limit greenhouse gas emissions.
Rogers worries that a blind jump to gas could leave the country
dependent on yet another fossil resource, without stemming the rate of
climate change.
“What if, with revelations around methane emissions, it turns out to be
only a 10 or 20 percent reduction of carbon from coal? If that's true,”
he said, “gas is not the panacea.”
The American Petroleum Institute said in an e-mailed response that
federal offshore drilling rules are already cutting down on the
emissions tallied by the government. Spokesmen for the Independent
Petroleum Association of America and the natural gas lobbying groups
Energy in Depth, American Clean Skies Foundation and America’s Natural
Gas Alliance, which have all been pushing to expand the use of gas,
declined to comment on the EPA’s new figures and what they mean for the
comparison between gas and coal.
But industry groups point out that gas looks attractive compared to the
alternatives.
Nuclear energy is less polluting than gas from a climate-changing
perspective, but it is costly and viewed skeptically in the United
States because of the dangers of disposing of radioactive waste.
So-called “clean coal”—including underground carbon sequestration—could
work, but the technology has repeatedly stalled, remains unproven, and
is at least 15 years away.
Renewable sources like wind and solar are being developed rapidly, but
the energy is expensive and won’t provide a commanding supply of
electricity for decades.
Gas, on the other hand, is plentiful, accessible and local.
Methane Is the Most Potent Climate Gas
Measuring the amount of natural gas that is leaking during drilling is
one challenge. Getting a grip on how that gas—which is mostly
methane—affects the environment, and what effect it will have on global
warming, is another. And on that, some scientists still disagree.
Greenhouse gases include carbon dioxide, as well as methane, propane
and lesser-known gases that also affect climate change.
For the purposes of standardization, all these gases are described
together using the unit Co2e, or carbon dioxide “equivalent.”
But because each gas has a different potency, or “warming” effect on
the atmosphere, a factor is applied to convert it to an equivalent of
carbon dioxide.
Methane, the primary component of natural gas and the most potent of
the greenhouse gases, has far more of an effect on climate change than
carbon dioxide. But determining the factor that should be applied to
measure its relative warming affect is still being debated.
To crunch its numbers, the EPA calculated the average concentration of
methane in the atmosphere over a 100-year period and determined that
over that period methane is 21 times more potent than carbon dioxide.
Using that equation, a ton of methane emissions is the equivalent of 21
tons of carbon dioxide.
But some scientists argue that the impact of methane gas should be
calculated over a shorter time period, because methane degrades
quickly, and because gas drilling releases large quantities of methane
into the atmosphere all at once, likely concentrating and amplifying
the effect.
Robert Howarth, an environmental biology professor at Cornell
University, used research from the United Nations to calculate that if
methane’s potency were considered over 20 years rather than 100 years,
it would be 72 times as powerful as carbon dioxide in terms of its
warming potential.
Figured that way, the climate effect of methane from natural gas would
quickly outpace the climate effect of carbon dioxide from burning coal.
Howarth’s research is incomplete and has been criticized because at
first he failed to figure in methane emissions from coal mining. But he
said that after correcting his error, the emissions from coal barely
changed, and the data still showed that the intensity of methane could
erase the advantages of using natural gas.
“Even small leakages of natural gas to the atmosphere have very large
consequences,” Howarth wrote in a March memorandum, which he says is a
precursor to a more thorough study that could begin to scientifically
answer these questions. “When the total emissions of greenhouse gases
are considered … natural gas and coal from mountaintop removal probably
have similar releases, and in fact natural gas may be worse in terms of
consequences on global warming.”
Howarth says his latest calculations show that the type of shale gas
drilling taking place in parts of Texas, New York and Pennsylvania
leads to particularly high emissions and would likely be just as dirty
as coal.
Environmental groups say factual data on how much methane is emitted
from gas fields—and what the warming affect of that methane is—should
be locked down before major policy decisions are made to shift the
nation toward more reliance on gas.
“You can’t just assume away some of these sources as de minimus,” said
Tom Singer, a senior policy analyst for the Natural Resources Defense
Council who focuses on emissions reporting in New Mexico. “You need to
get a handle on them before you can make a determination.”
Less Pollution Means More Profit
The EPA tracks fugitive and vented methane emissions through a program
called Natural Gas STAR and then works to get drilling companies to
save money by stanching their leaks and selling the gas they capture
for profit. It was a discrepancy in the Gas STAR data that prompted the
EPA to sharply revise the government’s greenhouse gas statistics late
last year.
According to Gas STAR’s most recent figures, at least 1.6 percent of
all the natural gas produced in the United States each year, about 475
billion cubic feet, is assumed to be leaked or vented during
production. But those numbers were reported before the EPA adjusted its
greenhouse gas estimates, and they are expected to rise when the new
estimates are plugged into the calculation. If companies could capture
even the gas leaked in Gas STAR’s current estimates, it would be worth
$2.1 billion
a year at today’s prices and would cut the nation’s emissions by more
than 2 percent right off the bat. Several studies show that maintaining
and installing equipment to capture the emissions pays for itself
within 24 months.
Gas STAR has seen some success in pushing companies to use these
capture tools. The EPA’s 2010 greenhouse gas inventory, using 2008
data, shows that even though more gas is being produced from more
wells, total emissions from that production have decreased by more than
26 percent since 1990, mostly due to the progress of Gas STAR. But
while these figures demonstrate that Gas STAR is effective in lowering
the annual rate of emissions, the EPA’s new figures essentially move
the starting point, and, when recalculated, 2008 emissions are now
understood to have been 53 percent higher than emissions in 1990.
That doesn’t mean the program isn’t working—it is. It simply means that
the road to making reductions significant enough to affect the rate of
climate change is much longer than expected.
The EPA now reports that emissions from conventional hydraulic
fracturing are 35 times higher than the agency had previously
estimated. It also reports that emissions from the type of hydraulic
fracturing being used in the nation’s bountiful new shale gas reserves,
like the Marcellus, are almost 9,000 times higher than it had
previously calculated, a figure that begins to correspond with Robert
Howarth’s research at Cornell.
Clean Enough to Count On?
Getting a solid estimate of the total lifecycle emissions from natural
gas is critical not only to President Obama’s—and
Congress’–decisions about the nation’s energy and climate strategy, but
also to future planning for the nation’s utilities.
Even small changes in the lifecycle emissions figures for gas would
eventually affect policy and incentives for the utility industry, and
ultimately make a big difference in how gas stacks up against its
alternatives.
Rogers, the Duke executive, says the country’s large promised reserves
of natural gas must also hold up for gas to prove beneficial, in terms
of both cost and climate. If domestic reserves turn out to be smaller
than predicted, or the nation runs out of gas and turns to liquefied
gas imported from overseas, then the greenhouse gas footprint of
natural gas would be almost equal to coal, Jaramillo pointed out in her
2007 lifecycle analysis, published in the journal Environmental Science
and Technology.
That’s because the additional processing and shipping of liquefied gas
would put even more greenhouse gas pollution into the atmosphere.
“In the 60’s we put a needle in one arm—it was called oil,” Rogers
said. “If the shale gas doesn't play out as predicted, and we build a
lot of gas plants in this country, and we don't drill offshore, we're
going to be putting the needle in the other arm and it's going to be
called gas.”
The utilities are in a bind because they have to build new power plants
to meet the nation’s demand for energy, while anticipating an
as-yet-undefined set of federal climate and emissions regulations that
they believe are inevitable. Do they build new gas-fired plants, which
can cost $2 billion and take three years to bring online? Or do they
wait for proven systems that can capture carbon from coal-fired plants
and sequester it underground?
If carbon sequestration works, coal-based power emissions could drop by
90 percent, said Nick Akins, president of American Electric Power, the
nation’s largest electric utility and the number-one emitter of
greenhouse gas pollution. That suggests to Akins that natural gas may
not be the solution to the nation’s energy needs, but rather the
transitional fuel that bridges the gap to cleaner technologies.
"Going from a 100 percent CO2 emitter to a 50 percent solution when you
could go beyond that is something we need to turn our attention to,”
said Akins. “If there is a 90 percent solution for coal, and other
forms like nuclear, and renewables, then obviously you want to push in
that direction as well.”