(The author is a Reuters market analyst. The views expressed
are his own.)
By Gerard Wynn
LONDON, April 25 More data on the greenhouse gas
emissions impact of shale oil and gas is needed to pinpoint
their climate impact, something which recalls a controversy
over Canadian tar sands where opposing lobby groups were said to
have cherry-picked data.
Shale gas has revolutionised the U.S. energy industry,
pressuring prices while tight (also called shale) oil production
is on a steep upward curve. Each was enabled by advances in
horizontal drilling technology.
The greenhouse gas (GHG) impact of shale gas is uncertain
but likely not much more than conventional gas, but next to zero
research has been made into emissions from tight oil.
The uncertainty problem rekindles the tar sands debate,
where green and industry lobbies have squared off by exploiting
uncertainty in emissions numbers, confusing assumptions, tar
sands projects (some are cleaner running) and an error margin of
about 5 percentage points.
Doubt is multiplied for shale gas and oil -- newer
technologies with an even less settled academic view.
Critical questions include: how do the direct GHG emissions
compare with conventional fossil fuels; will they displace coal
CO2 emissions or add to them; and how pressing is the wider
The context for the climate problem is that humankind can
only emit a certain total of GHGs and stay within an
international target limiting global warming to no more than 2
A letter published in the journal Nature in 2009 calculated
that "emissions budget" to be 1,440 billion tonnes of CO2 from
2000-2050. By 2010, the available budget had already shrunk to
about 1,100 billion tonnes.
Global CO2 emissions in 2010 were 36.5 billion tonnes,
including deforestation plus burning fossil fuels, according to
data from the energy company BP and the Global Carbon
Project research group.
Continuing such levels would swallow up the remaining budget
by 2040, when global CO2 emissions would have to stop
That's hardly practicable, implying one of two options: miss
the warming target or cut emissions sooner.
It follows that environmental regulation will probably get
tougher, and that shale fuels should be at least no more
CO2-emitting than conventional fossil fuels.
SHALE VS. CONVENTIONAL
The trouble with natural gas is that its core ingredient is
methane, a greenhouse gas (GHG) with a much stronger global
warming potential than CO2.
In the case of shale gas extraction, methane can leak both
from ("flowback") fluids used to blast gas out of the fractured
shale rock, or from drilling of wells - the first process does
not apply to conventional natural gas.
The range of shale gas GHG emissions is defined by a handful
Near the top end, Cornell University scientists last year
estimated that methane emissions were at least a third higher
than for conventional gas, making shale gas comparable to coal,
widely regarded as the most climate-unfriendly fossil fuel.
That followed a U.S. Environmental Protection Agency (EPA)
study which concluded that methane leaks may be far higher than
with conventional gas. Earlier this year the Cornell authors
recently stood by their research.
Nevertheless both have been criticised.
For example, the consultants IHS CERA said that such high
levels of (flammable) methane emissions would be impossible in
practice, simply as a fire hazard.
It said the EPA and Cornell studies misunderstood industry
practice (for example, exaggerating methane venting into the
atmosphere), and used a simplistic and inappropriate averaging
Regarding North America's burgeoning tight oil, there is
even less to go on - with all but zero CO2 research, experts
Shale oil is on track to be a significant part of U.S. crude
production, presently nearing a tenth of domestic output.
Possible CO2 problems may include gas flaring, but probably
pale against the emissions impact of pumping steam into sand to
extract tar crude in Canada.
The answer to resolving the CO2 impacts is more data, and
putting in place often simple response measures, for example in
the case of shale gas containing methane emissions by housing
rather than exposing flowback water.
The IHS CERA report applauded EPA regulatory proposals if
these codified best practice and led to wider emissions
Without more data, doubts will grow and industry lag best
practice, inviting misunderstanding and protest.
(Editing by Keiron Henderson)