A bright future for fossil fuels?
Will
storing greenhouse gases in underground reservoirs allow us to tackle
climate change immediately, while making an easier transition to a
low-carbon economy?
250 km of the coast of Norway, the Sleipner-West
gas platform stands over the stormy waters of the North Sea. It looks
no different to any of the other huge conglomerations of steel that
dot the waters of Norway’s highly productive gas and oil fields,
but this platform is home to a unique and controversial experiment.
Some believe it will be an essential step towards the rapid and substantial
reductions in greenhouse gas emissions necessary to prevent global
warming; others see it as a dangerous attempt to dump industrial waste
beneath the ocean floor.
Since 1996, Norwegian petroleum company Statoil has been pumping a
million tonnes of carbon dioxide (CO2) a year into a saline aquifer
800 metres below the seabed. Rather than escaping into the atmosphere,
Statoil scientists believe the gas will remain trapped within the
aquifer for thousands of years, thus making no contribution to the
greenhouse effect.
The CO2 stored so far only amounts to 3 per cent of Norway’s
annual emissions, but its total capacity could be as much as 600 billion
tonnes of gas. According to Dr Tore Torp, manager of the project,
this means, “the entire carbon dioxide emissions from all the
power stations in Europe could be deposited in this structure for
600 years.”
Few dispute that climate change is fact, or that human release of
CO2 into the atmosphere is its main cause. With each passing year,
more evidence accumulates warning us of the dire consequences we face
if we do not address the problem very soon. Yet still the political
will to address the problem is lacking.
The Kyoto Accords of 1997 were supposed to be the first step towards
tackling climate change, committing the world’s biggest polluters
to emissions reductions by 2010. But the intervening years have seen
the agreement steadily eroded, and it suffered a critical blow when
the Bush administration pulled out in 2001. Even some of Kyoto’s
most enthusiastic backers in the EU do not look like meeting their
targets. It would be the final nail in the treaty’s coffin if,
as recent announcements have hinted, Russia does not ratify.
The politics involved are complicated, but it all seems to come down
to one thing in the end - money. A Russian presidential aide stated
that Kyoto would place, “significant limitations on the economic
growth of Russia.” He was echoing the words of George W Bush,
who abandoned the treaty claiming it would damage the US economy.
Whether or not these arguments are valid, there is no question that
fossil fuels are the foundation of the world economy; doing without
them would require dramatic changes in the way our society functions.
We citizens of the West are oil and gas junkies, and few of us are
willing to suffer the hardship of going ‘cold turkey’.
In this context, Statoil’s project (and others like it) may
offer a middle way, giving immediate reductions of greenhouse gas
emissions, but allowing a more gradual shift from fossil fuels to
renewables. We could effectively put the carbon genie back in its
bottle. The big question is - will it work?
The concept of capturing CO2 and storing it underground, a process
known as geological carbon sequestration, has been around for at least
25 years. Gas-separation technology is used every day in heavy industry;
CO2 is also routinely pumped into oil fields nearing the end of their
lives, forcing out the remaining oil in a process known as enhanced
oil recovery. However, it is only in the last decade that policy makers
began looking seriously into its potential for reducing emissions
of greenhouse gases.
CO2 is present in all flue gases produced by burning fossil fuels.
However, it only constitutes a small part of the total volume; most
of the flue gas is nitrogen, oxygen and water vapour. Before it can
be stored, the CO2 must be separated out from the other gases.
Many proven technologies, such as chemical scrubbing, physical absorption
or separation with membranes, can achieve this. It is also possible
to process a fuel before combustion, separating it into pure hydrogen
(which produces only water when combusted) and CO2. These methods
can capture up to 80 per cent of the CO2 for each unit of electricity
generated, a substantial reduction.
Applications for this technology are not limited to power generation.
Major industries like iron and steel production, cement manufacture
and oil refining account for three quarters of industrial CO2 emissions,
around 60 per cent of which could be captured. Large-scale production
of pure hydrogen could also allow a faster shift to zero-emissions
vehicles using fuel cell technology. Broad application of carbon capture
could put us well on the way to the 60 per cent reduction emissions
necessary to stabilise atmospheric concentrations of greenhouse gases
and prevent further climate change.
Distributing the captured gas would require little innovation. Existing
networks of natural gas pipelines would need only minor modifications.
Onshore pipelines already transport CO2 over hundreds of kilometres
in the USA. There is also no shortage of suitable geological structures,
from salt caverns and saline aquifers to disused oil fields and unminable
coal seams. The total storage capacity of these underground reservoirs
is many times greater than the projected global CO2 output over the
next 50 years.
There
are only two carbon sequestration projects in action today. The Sleipner-West
project in Norway works by removing excess CO2 from a natural gas
field and re-injecting it into a neighbouring aquifer. The Weyburn
project in Canada is pumping a million tonnes of the gas per year
(delivered via a 320 kilometre pipeline from a synfuels plant in the
USA) into a depleted oil well, forcing out an anticipated 122 million
extra barrels of oil over its twenty-year duration. Both are crucial
test cases, and so far very successful.
The actual cost of implementing carbon sequestration on a commercial
scale is more uncertain. Transporting and storing gas is fairly inexpensive;
the greatest part of the cost would be capturing the CO2. In an October
report, the British Department of Trade and Industry (DTI) concluded
that the cost of carbon storage under the North Sea would add 16-36%
to the current price per unit of electricity. If used in conjunction
with oil recovery, the price would increase by 3-16%, due to the offsetting
effect of increased oil productivity. This compares to an estimated
price increase of around 25% per unit of electricity to achieve the
government’s goal of generating a fifth of our electricity from
wind power by 2020.
Offsetting this cost and making carbon sequestration commercially
viable would require a strong policy incentive. Statoil’s motivation
for pumping CO2 into the Utsira aquifer is the £86,000 per day
they would have to pay in Norwegian carbon taxes if they were to release
it into the atmosphere. If a similar project is to be implemented
in the UK, the DTI says it is vital that the European Union’s
Emissions Trading Scheme gives financial credit for the abatement
of greenhouse emissions. This would provide the necessary incentive
for investors in the technology, but will only be considered if long-term
storage is proven safe.
On the night of 22 August 1986, an underwater volcanic explosion in
Cameroon’s Lake Nyos released a huge cloud of carbon dioxide
over the surrounding countryside. CO2 is an asphyxiant and is heavier
than air; it covered the land in a suffocating blanket that extended
15 miles from the lakeshore. 1,700 villagers were killed, 845 were
hospitalised and 3000 cattle lay dead in the fields.
This tragic natural disaster shows the full horror that a sudden rupture
in an onshore storage reservoir filled with CO2 could entail. The
effect of such a release under water is largely unknown, but would
likely have equally lethal consequences for sea life. Slow leakage
from a reservoir would not have such a dire effect, but would ultimately
put the gas back into the atmosphere and make the whole exercise pointless.
Clearly, if we put CO2 under the ground, we need to be sure that it
will stay there for thousands of years.
Scientists involved with the projects in Norway and Canada are confident
of their safety and reliability. Dr Tore Torp, who has been using
seismic surveys to study the Sleipner aquifer since 1999, believes
the CO2 will remain there for thousands of years. “Once it dissolves
in the water,” he says, “it will be very secure. You would
have to pump it out.” Similar surveys conducted at the Weyburn
site also show that so far the CO2 is staying put. Scientists there
are currently developing computer models to determine how the gas
will behave over the next 5000 years.
The data in these cases is certainly positive, but the extent to which
it can be applied to other sites over the necessary timescales is
questionable. Every potential reservoir has a unique geological structure.
Each would have to be assessed for safety before a sequestration project
could begin - a fact that leaves environmental groups deeply sceptical.
“There is virtually no evidence of what the leakage rate is
likely to be,” says Roger Higman, climate change campaigner
for Friends of the Earth. “One per cent per year would be absolutely
unacceptable. You would lose virtually all of it within 130 years.
Even a leakage of 0.1 per cent would produce a greenhouse effect that
future generations would be hard pressed to stop. It’s like
the issue of nuclear waste management; it’s potentially impossible
to prove that something won’t happen over a timescale of a thousand
years. The only thing you can guarantee is that if you don’t
take the oil, gas or coal out of the well in the first place, you
don’t have a problem.” The consensus in the environmental
community is concentrating on novel technologies that may never come
to fruition is foolish when we already know that approaches like energy
efficiency and renewables are effective.
The debate over the future of carbon sequestration is only just beginning,
but it seems likely that it will be a part of future energy policy.
In an October report, the DTI made it part of their overall strategy
to reduce CO2 emissions by 60% before 2050. The outline for a possible
demonstration project in the North Sea is expected later this year.
The US Department of Energy is particularly keen, with plans to start
pumping CO2 into a depleted oil field in Wyoming in 2006, and more
projects likely to follow. The Dutch government, and the EU-sponsored
‘CO2Store’ project, are investigating other sites in Europe,
including one in the Dulais Valley of South Wales.
Many eyes will be focussed on these projects in the coming years.
Whatever the eventual outcome, there can be no question that a problem
as serious as climate change needs immediate action, using as broad
a spectrum of solutions as possible. “There isn’t one
‘magic bullet’ solution,” says Nick Riley of the
British Geological Survey. “We need renewables, energy-saving,
carbon dioxide capture and storage – the whole lot. We need
to attack this from every available front and we have to do it all
over the next few decades.”
