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A MUltiple Space and Time scale approach for the quAntification of deep saliNe formations for CO2 storaGe

WHAT IS CO2 CAPTURE AND STORAGE?

THE CLIMATE CHANGE

The greenhouse effect is a natural phenomenon, which is indispensable to maintain on the Earth an adequate climate for life. Greenhouse gases in the atmosphere block part of the energy that the Earth receives from the sun, and allow maintaining a warm temperature. However, since the beginning of the industrialized era, the concentration of the greenhouse gases in the atmosphere increased rapidly, mainly due to the massive use of fossil fuels (coal, oil and gas). It is yet widely recognized that an excess of greenhouse gases in the atmosphere increase the average temperature on the earth, besides perturbing the complex network of natural phenomena that maintain the weather and the temperature on the Earth stable.

The most important greenhouse gases are carbon dioxide (CO2), methane (CH4), nitrous oxides (NxOy), ozone (O3), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6). The concentration of greenhouse gases in the atmosphere is measured in terms of CO2 equivalents, because CO2 is responsible for over 60% of the increase in the greenhouse effect.

The likely consequences of the climate change on the Earth include, among many others, increase of extreme events (e.g. hurricanes, floods, droughts), increase of the sea level due to glacier smelter, extension of desertification, loss of biodiversity.

Climate change represents one of the greatest environmental, social and economic threats that the planet is facing. In order to reduce climate change, greenhouse emissions should be reduced significantly in the next few decades. The United Framework for Climate Change (UFCC) asked for a decline of the emissions of 50% over 2000 levels by 2050, which will correspond to an average increase of 2-2.4º in the temperature on Earth.

WHAT IS CARBON CAPTURE AND STORAGE?

Carbon capture and geological storage (CCS) may contribute to the reduction of the CO2 emissions in the atmosphere, and thus to the mitigation of the greenhouse effect. CCS allows trapping large volumes of CO2 from large carbon emitters (such as coal-fired power plants) and injecting it into the ground in suitable geological storage sites (e.g. saline aquifers, oil and gas reservoirs, and coal beds).

In order be stored, the CO2 must be separated, compressed and transported to the site chosen for sequestration, such as oil and gas reservoirs, unmineable coal seams, and deep saline reservoirs.
 
The 2005 IPCC Special Report on CCS concluded that the fraction retained in appropriately selected and managed geological reservoirs is very likely to exceed 99% over 1000 years.

Although the different phases of CCS are all known and deployed at commercial scale, integrated systems are new. For this reason, research is still needed to ensure that the stored CO2 remains isolated from the atmosphere in the long term and that transport and storage do not present risks for human health or ecosystem.

How does CCS work?
This figure shows how CCS works in a schematic way.


CCS process
 CO2 emissions

Power plants (such as coal power plant, gas power plants, steel and cement plants) emit not only CO2, but also harmless steam and nitrogen, into the atmosphere.

 CO2 Capture

CO2 emissions from power plants (mainly coal power plants) is captured and separated from the other components. Due to the fact that flue gas contains only 10% of CO2 it is better to separate it from the other gasses to get the smallest possible volume for transport and storage. This separation process is named CO2 capture. There are many different technologies for capturing CO2.

 Transport

The sequestered CO2 is transported to a suitable storage location. To make this possible, CO2 must be dried in order to remove water which could cause corrosion problems; and also must be compressed. Transportation can be by ship or pipeline, depending on the distance.

 Storage

CO2 is stored more than 800 metres below ground. There are several storage options, but only in locations where we are sure it will not leak out again. The CO2 can be injected in oil and gas fields or in saline aquifers. Saline aquifers contain porous sandstone where water is present naturally in the pores in the sand. The injected CO2 occupies the pores like water does or it can even be dissolved into the water.. CO2 would be stored in saline aquifers to avoid decreasing fresh water reservoirs.

 Monitoring

For CO2 storage to be permanently safe, monitoring and verifying that there is no leakage of CO2 from the storage reservoir should be undertaken.

 Communication

An important obstacle for the deployment of CCS as a new technology could be related to public awareness. Some characteristics of this technology may cause societal resistance upon actual implementation, like the possible leakage of carbon dioxide from the storage reservoirs and its impact on the local environment (IPCC, 2005).

In this regard, it is very important, for a successful development of this new technology, to build public confidence by providing open, clear, two-way and well-time communication in the broader context of climate change and the range of possible solutions for a more sustainable future.

In this regard, involved stakeholders (policy makers, regulators, industry, NGOs, etc) should work together during all the processes of CCS technology deployment.

CO2 CAPTURE AND STORAGE IN DEEP SALINE AQUIFERS

In order to have a significant impact on the climate, the amount of CO2 sequestered needs to be extremely large and therefore it would be impossible to use man-made containers. The best option is therefore to use natural storage facilities. Deep saline aquifers offer the largest storage potential and are widely distributed throughout the globe in all sedimentary basins.

MUSTANG will contribute to analyze the potential for the long-term storage of CO2 in deep saline aquifers through the development and dissemination of a comprehensive set of methodologies and tools. Moreover, MUSTANG will provide measures of performance and risk, which are necessary to undertake a thoughtful cost-benefit analysis of using deep saline aquifers for CO2 storage.


IF YOU NEED MORE INFORMATION…

 Information on CSS from the European Commission

http://ec.europa.eu/environment/climat/ccs/what_en.htm

 Intergovernmental panel on climate change

http://195.70.10.65/organization/organization.htm

The Intergovernmental Panel of Climate Change (IPCC) is the leading body for the assessment of climate change, established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) to provide the world with a clear scientific view on the current state of climate change and its potential environmental and socio-economic consequences.

 The IPCC has elaborated a special report on CSS

http://www1.ipcc.ch/pdf/special-reports/srccs/srccs_wholereport.pdf

©Mustang - 2009