Carbon dioxide (CO2) is a natural gas that allows sun to the Earth,
but also keep the sun's heat from the transmission back into space, so
that the Earth becomes warmer. Scientists refer to this as the warming greenhouse effect.
When this effect works naturally, the Earth becomes warm enough to
support life. If we do not have a greenhouse effect, the Earth would be
at an average temperature of minus 30 degrees Celsius. Carbon dioxide and the greenhouse effect is necessary to sustain the Earth. But the wide range of human creations such as power plants
and transportation vehicles that use fossil fuel combustion, releasing
extra carbon dioxide into the air. Since we added and continue to add
carbon dioxide to the atmosphere, so more heat is trapped in the Earth,
causing the Earth's temperature crept up. This phenomenon is called
temperature increase global warming.
Carbon
dioxide is not the only greenhouse gas. Other greenhouse gases are
water vapor, methane, nitrous oxide, hydrofluorocarbons,
perfluorocarbons, and sulfur hexafluoride. Scientists estimate that greenhouse gas emissions
worldwide by human activities increased 70 percent between 1970 and
2004. Emissions of carbon dioxide alone rose 80 percent in the same
period.
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| Geoengineering and carbon storage proposals: Some aim to reduce incoming solar radation, others to remove atmospheric carbon dioxide and sequester it underground, in the oceans or in vegetation. (Picture from: http://www.earthmagazine.org/) |
To
reduce carbon dioxide emissions, some experts recommend to capture
carbon dioxide before it escapes into the atmosphere. The way is known
as carbon capture and storage (or carbon capture and sequestration / CCS).
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| How carbon capture works. (Picture from: http://news.bbc.co.uk/) |
CCS
is a process that removed carbon dioxide capture from large sources
such as power plants powered fossil fuels, carbon diosida then transport
it to a storage / isolation, and precipitate it thus not released into
the atmosphere.
The
location is ideal for carbon capture and storage system course power
plants that use fossil fuels (coal, petroleum, and natural gas) and
produce thousands of tons of carbon dioxide every day. IPCC (Intergovernmental Panel on Climate Change) United States
estimates that a power plant equipped with CCS systems can be managed
to reduce net carbon dioxide emissions by 85 to 95 percent.
So,
where the carbon dioxide that is captured is stored? One of the
locations that can be used for carbon storage is the bottom of the
ocean. The concept of storage of carbon dioxide in the ocean floor was
first introduced by Michael Pilson. Simply put, the theory is liquefying
carbon dioxide, then put it into the ocean. Atmospheric pressure and
low temperature in the environment of the ocean keep the liquid carbon
dioxide to float, so that carbon dioxide was infiltrated / sink and not
float on water.
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| Overview of ocean storage concepts. In “dissolution type” ocean storage, the CO2 rapidly dissolves in the ocean water, whereas in “lake type” ocean storage, the CO2 is initially a liquid on the sea floor. (Picture from: http://www.global-greenhouse-warming.com/) |
The
reaction between carbon dioxide and liquid water in the deep ocean at
high pressures and low temperatures cause the carbon dioxide back into
ice compounds called clathrate hydrate. When in the form of clathrate
hydrate, carbon dioxide should be maintained in this form so as to avoid
absorption by sea water.
At
the end of the 20th century, various experiments were conducted to
monitor whether the storage of carbon dioxide in the ocean possible.
Researchers at the Monterey Bay Aquarium Research Institute
include liquid carbon dioxide into a glass on the ocean floor at a
depth of 3.600 meters. Carbon dioxide is grown in large volumes and
split into clumps, which can be swept away by the ocean currents.
However, the problems that arise and need to be addressed is the release
of large amounts of carbon dioxide into the ocean could disrupt ocean
ecosystems.
In
2008, a group of researchers from different areas in the United States
led to an idea for a liquefied carbon dioxide should be stored in a
secure area of the ocean floor and little or no marine life. The area
that became the choice is abyssal plain.
Abyssal
plain is a very vast ocean that stretches from the base of the
continental slope to the trough zone, where the gorge in the Mariana Trench
cut like the ocean. Abyssal plain began at a depth of 4.000 meters. In
this place, sunlight for photosynthesis very little or nothing. Supply
of food for life in the place obtained from dead or decaying plants
infiltrated the ocean floor. Populations of rare animals in the abyssal
plain, and the area is wide and generally flat.
At
a depth of about 4,000 feet, the temperature was about 2 degrees
Celsius and atmospheric pressure of 413.3 kilograms per square
centimeter. The environment is very different than at sea level
atmospheric pressure which has a 1.03 kilogram per square centimeter and
an average temperature of 14.77 degrees Celsius globally in 2005. With
these conditions, the abyssal plain being an ideal location for storing
liquid carbon dioxide.
David Keith in a lecture at the American Association for the Advancement of Science
in February 2008 stated that the abyssal plain into place for the
placement of a large bag made from polymers, with a diameter of about
183 meters which serves as a storage container for liquid carbon
dioxide. Carbon dioxide sent into the ocean through a sewer pipe, as
well as drainage of crude oil to refineries. If this concept is
practiced, a large pouch pengurung must awake from a leak or release
large amounts of carbon dioxide into the ocean so it does not damage the
ocean ecosystem.
Injection
and storage of carbon dioxide in the ocean can not be separated from
the problem. One of the concerns that will be a problem is the level of
security and leaks that have an impact on the increase of carbon dioxide
in the water so that the acidity of the water increases. Water with
very high acidity unfavorable effect on marine life. For example, acidic
water reduces the amount of sea creatures that are in need of calcium
carbonate to form their shells. In addition, the storage of carbon
dioxide in the ocean requires a cost / large funds. *** [EKA | FROM VARIOUS SOURCES | BBC | GLOBAL GREENHOUSE WARMING | DEDE NURROSYID | PIKIRAN RAKYAT 11042013]
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