| 
CO2 storage - one piece of the global warming solutions'
puzzle
Time to keep dust under the carpet
Whatever you have bought lately, it is almost certain it came in a wrapper
or package that you ripped off straight-away and put in the bin. And there is
no shred of doubt that oil, at least in one stage of the production process, has
played a crucial role, be it serving as fuel to generate electricity or as raw
material, what presents us with an impressive reality of consumption made up of
one thousand barrels of oil per second. Linked to that, tons of carbon dioxide
- one of the gases most responsible for the greenhouse effect - run together.
So, the geological storage of CO2 has been increasingly focused as a solution
to mitigate this enormous emissions rate. Although most experts vigorously defend
this alternative, the subterranean storage of CO2 still causes controversy
By LUAN
GALANI
from Curitiba, BRAZIL
 "The
idea is to capture CO2 from large industrial sources (oil refineries, cement factories,
mining houses, glassworks and steel industries, among others) before it enters
the atmosphere and store it deep underground in secure geological formations where
it would be stuck for a long period of at least 500 years", explains John
Bradshaw to WAVE magazine. This Australian geologist is the chief executive
of Greenhouse Gas Storage Solutions - a subsidiary of an oil consulting firm -
and a former scientist of the Intergovernmental Panel on Climate Changes (IPCC)
when it won the Nobel Prize in 2007.
About one third of the CO2 emissions
of human origin comes from fossil fuels used to generate electricity in factories.
If injected into some of the biggest sources of these fuels, such as coal seams
and fields of oil and gas, the atmosphere would be free of millions of tons of
CO2 every year.
"But it is not possible to store the CO2 which is
in the air. At that stage it is just a little concentrated and comes from several
small scattered sources", says geologist Joćo Ketzer, coordinator of the
Centre for Excellence in Research on Carbon Sequestration, which is affiliated
to Petrobras, an important Brazilian company in this area. According to a survey
carried out by the consulting firm Ernst & Young, Petrobras is the world's
eighth biggest global company in market value nowadays. So, coming back to the
main issue, injecting carbon dioxide into the subsoil does not solve the growing
problem of CO2 emission by the means of transport, though.
The volume of
CO2 generated is so vast that we need to think about different ways to reduce
such emissions, advises Bradshaw. According to him, the ongoing projects for carbon
sequestration can store just a small portion of all the CO2 that must be removed
from the atmosphere to achieve the desired levels. Bradshaw recalls that 3,500
Sleipners would be necessary to solve the problem of emissions worldwide.
Thus,
the capture and geological storage of CO2 appear as an option with great potential,
especially if associated with other alternatives, such as developing new sources
of renewable energy and obtaining greater efficiency. That is a technology transition
while fossil fuels are not replaced by alternative sources of energy generation.
"We must change our consumption habits, which is about a thousand barrels
of oil per second nowadays", defends Ketzer.
Risks and drawbacks
 Detractors
of the storage of CO2 tend to focus on the risk of leakage of the gas injected
into geological formations as one of its main drawbacks. Currently, there are
several ongoing studies to evaluate such hypothesis. Since the reservoirs present
specific risks, each one must be carefully evaluated.
For Euripides Vargas
Jr., a researcher at the Department of Civil Engineering of PUC-Rio de Janeiro,
although chances are slim, risks of leakage will always exist. "The ones
that can be remedied as soon as they are identified are tolerable," he ponders.
Ketzer, on the other hand, is optimistic with respect to this issue. "If
there is a leakage, it will be in a small amount and for a short period, unlike
other gas leakages considered dangerous, which occur in large amounts for a long
time."
Many organisations consider that leakages of carbon dioxide
can cause serious impacts such as the acidification of oceans and aquifers, in
addition to the death of thousands of living beings. Ketzer, however, demystifies
the thesis that the CO2 injected is as evil as common sense would suggest. According
to him, many people around the world bathe themselves in geysers (hot springs
that erupt and release gases), which have a much higher concentration of CO2 than
that of wells and reservoirs. "However, neither the flora or fauna - let
alone people - are ever killed by the gas."
On the other hand, impacts
can be severe depending on the leakage, as Euripides points out. He recalls that
a leakage of large amounts of CO2 to the atmosphere in 1986, whose causes still
remain unknown, was dissolved in the water of Lake Nyos, Cameroon, Africa. At
night, a cloud of gas floated along the villages nearby. Since CO2 is heavier
than the air, it remained close to the ground and killed 1,700 people during their
sleep. "This shows the lethal power of a leakage," he concludes. Ketzer
remembers, though, that the geological conditions of the subterranean stocks of
CO2 and those of Lake Nyos are completely different.
The reservoirs
There
are four main types of geological reservoirs for the storage of CO2: geological
oceanic formations, saline aquifers (unsuitable for human use), coal seams and
gas and oil reservoirs in operation or not. The carbon dioxide is captured in
its sources of emission before entering the atmosphere. Then, the referred gas
is compressed and transported in the liquid state to be stored in the suitable
geological structure.
 According
to IPCC, 20% to 40% of the global CO2 emissions from fossil fuels could be technically
adapted for storage until 2050. By 2100, the organization estimates that from
220 billion to 2.2 trillion tons of CO2 might be stored in the Earth's crust,
covering from 15% to 55% of the global pollution by the end of the century.
Due
to the high costs of production, transport and storage, the storage is, at least
for the moment, economically unfeasible. "The sequestration and compression
of CO2 are responsible for 60% of the costs; transport and injection 40%",
explains Ketzer. New studies have been done in order to reduce those costs. "It
is expensive, but the governments have to set goals," says Brandshaw. "Up
to now, US$1,7 trillion has been spent on the war in Iraq; many things could have
been done in terms of research in this field with that amount of money. The point
is to decide whether we want to pay for our attitudes right now or years on".
Brazilian
action
According to Ketzer, thanks to its sedimentary basins, Brazil
has a great capacity for the geological storage of approximately 2 trillion tons
of CO2. "It corresponds to decades of global emissions at current levels,"
he compares. With such potential, the country has the opportunity to become an
important agent in the process of mitigating climate changes.
Last semester
Petrobras began to store CO2 in basins in Rio and in Bahia. Furthermore, it considers
holding the gas in pine, bamboo and eucalyptus forests and also in microalgae.
Nevertheless, the most important research in the area is not Brazilian. When one
analyses the global market for carbon sequestration, there is an exponential growth
of the participation of Asian countries that have surpassed Latin America as the
leading international agents, being responsible for more than twice as many projects
in development nowadays.
Past, present and future
The injection
of CO2 in subterranean geological formations was primarily made in Texas, United
States, in the early 1970s to facilitate the extraction of oil as the carbon dioxide
makes oil more fluid and lighter. Little research had been done until the early
1990s, though, when the idea gained credibility.
The first project on CO2
storage in large scale in the world was initiated in 1996 by Statoil, a giant
Norwegian oil company and its partners on the Sleipner gas field in the North
Sea. The storage, in a saline formation located 250 km off the coast of Norway,
is one million tons of CO2 per year. British Petroleum, a powerful British oil
company, estimates that the reserves in the North Sea could store all the CO2
produced in 50 years by the processes of energy generation in Europe.
According
to the International Energy Agency, there are about 150 ongoing projects on CO2
storage in the world. Scientists estimate that, on average, a single project could
remove one million tons of CO2 from the atmosphere every year - the equivalent
to the emissions released by 100 thousand cars in the same period.
In the
United States, the giants General Electric and ExxonMobil - the second and fifth
most important companies in the world respectively, according to a report in the
North American Forbes magazine in 2008 - Stanford University (USA) is among the
several sponsors of a project on energy and climate changes, which studies mechanisms
of storage and monitoring of CO2.
In Germany, the first works aiming at
CO2 storage began in the test moat of Ketzin, in Berlin. The goal of the National
Centre for Geosciences in that country is to have stocked 60 thousand tons of
carbon dioxide by the end of the project. The amount of gas researchers hope to
capture in the subsoil in two years corresponds to the one the population of the
city of Potsdam - approximately 145 thousand inhabitants - breathes out in the
same period. Another important project is the Salah, in Algeria, led by large
companies in this field, such as Sonatrach, British Petroleum and Statoil, who
are injecting CO2 at 1,800 meters under the surface.
The rise of new ways
of absorbing and storing carbon as alternatives to mitigate the problems caused
by climate changes around the world is obvious. Although these technologies are
still economically unfeasible, in the near future they are bound to help solving,
at least partially, the serious consequences of global warming. However, we have
to bare in mind that sweeping our dust under the carpet will have outcomes. And
I strongly hope it doesn't come back to haunt us.
(Published:
12.09.2009.)
| |
