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Abstract
The geological sequestration of CO2 is a relatively new technology that seems to have rapidly maturated in providing an effective process of capturing CO2 from industrial pollutant emissions and storing it securely in deep geological formations. Through this technology, the anthropogenic CO2 emissions can be reduced by 20% globally by 2050. Furthermore, it is expected that by the end of this century, more than 55% of CO2 emission can be captured and stored geologically. The
compression, the transport and the injection of CO2 have been well used and controlled in the petroleum industry for many decades. However, CO2 capture process remains the weak point that should be overcome in order to make CCS economically feasible at industrial level. Moreover, no risk of leakage can occur at very long term in order to make CCS technology possible and generalized.

The objective of this review is to analyze and to compare briefly the quantification of CO2 emissions in Algeria and to illustrate, with different case studies, the worldwide geological CCS pilot projects, particularly, those applied at industrial scale. The review is an attempt to assess critically what has been done and to predict what is ahead in this domain.

Based on this review, the authors conclude that the global warming is the consequence of human egocentrism. CO2 should be considered as a valuable gas and not a waste, and CCS as a solution to global warming. Although there is negligible CO2 emission in Algeria, In Salah CCS project, built by BP-Statoil-Sonatrach consortium, is for demonstrating that pollution has no boundaries and every country is concerned by environmental issues. Thus, developing and developed countries should be urgently implicated in a serious and strong cooperation in the deployment of CCS technology before reaching irreversible global warming consequences.

1. Introduction
Human activities are responsible for 36% increase of anthropogenic CO2 in the atmosphere from the beginning of the industrial era, 1800. The sources of these emissions are: the combustion from fossil fuel energy (coal, petroleum and natural gas), cement production, deforestation … (Martin et al., 2008). The massive GHG increase, particularly CO2, has caused climate disturbance followed by devastating natural consequences.

The geological sequestration of CO2, called Carbon Capture and Storage (CCS) is considered as one of the most efficient solutions that contribute to overcome climate change disequilibrium. It may contribute to the reduction of:

1. GHG emissions: approximately 20 to 30% of CO2 emission can be cut at world level (BIP, 2009; Qurkis, 2009).
2. The rise of atmospheric temperature: To limit the increase of 2°C by 2050, the emission of CO2 in 2000, evaluated by Tier 1 sectoral approach to be 23.5Gt (IEA Statistics, 2011), should be reduced at 85%; otherwise, the temperature will increase by 4 to 7°C (Qurkis, 2009).

If this temperature remains at this rate, and if we take 0.34 mm/yr as a gradient, expected by IPCC, for the last 15 years to evaluate sea levels versus temperature increase (Huybrechts et al., 2001; Chapron et al., 2010), the average oceanic level will be elevated by 0.2m in 2100. Recent studies, (Allison. I et al., 2009), indicated that IPCC prediction was low and the level may surpass 1m and reach 2m at the end of this century. In addition, the average pH of surface oceanic that is now near 8.1 has already decreased by 0.1unit from the beginning of industrial era. It may decrease by 0.2 to 0.4unit at the end of this century (Martin et al., 2008).