Storing CO2 in the Ocean

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.

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).

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.

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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