CO2 Capture and Storage
Climate change, especially in the recent years, is one of the biggest problems encountered at the global scale. Increase in carbon dioxide (CO2) and other greenhouse gases (methane-CH4, dinitrogen monoxide-N2O, hydrofluorocarbons -HFCs, perfluorocarbons PFCs, sulphur hexafluoride -SF6) causes global warming and climate change consequently, due to greenhouse effect in the long term.
For this incident that threatens the nature and the mankind in the long term, 195 countries reached an agreement at the 21st UN Conference of the Parties (COP21), which was organized in Paris in December 2015, to take action to reduce the greenhouse gas emissions to drop the global temperature increase below 2°C until 2030. As a result of this conciliation, Paris Agreement was approved by 55 countries, which were responsible for minimum 55% of the global greenhouse gas emissions. Our country signed the Paris Agreement at the High Level Signing Ceremony convened in New York on 22 April 2016 with the 175 country representatives and the agreement entered into force as of 4 November 2016.
National contributions serve a significant foundation for realizing the goals of the Paris Agreement. Our country has announced its “Intended Nationally Determined Contribution (INDC)” declaration, which is projected to be realized as of 2030, as 21% decrease in the increase.
According to the International Energy Agency (IEA), the efficiency ratios will be as follows for reducing the global carbon emission until 2060: energy efficiency 40%, renewable energy 35%, carbon capture and storage 14%, other methods 11%. Studies at global scale are carried out in energy efficiency and renewable energy for long years and various technologies have been developed during this process. Carbon capture technology has a background of about 80 years and the carbon captured here is emitted into the atmosphere. It can be said that carbon capture and storage (storage of the captured carbon at the storage areas and disposal) is relatively new. Methods developed in this area at the industrial scale are more limited than the energy efficiency and renewable energy techniques.
Industrial-scale carbon capture and storage techniques, which still have high investment costs in our day and require improvement, can be reviewed under three captions in general. These are Pre-Combustion CO2 Capture, Post-Combustion CO2 Capture and Oxy-fuel techniques. These techniques are still at the development stage in our day.
In pre-combustion capture technique, the solid fuel transforms into gas fuel form upon being heated in a pressured environments rich in vapor and oxygen. This fuel is a combination of hydrogen and carbon monoxide and is also called as syngas. In this technique, carbon is decompounded by means of physical and chemical absorption methods before the syngas is burnt.
In post-combustion technique, the carbon dioxide released after combustion is separated with the help of the chemical dissolvers and then stored.
In oxy-fuel technology, high purity oxygen is used instead of air for combustion. In this way, higher temperature is obtained as a result of combustion and the emitted flue gases rich in CO2 and H2O can be reused with the burners.
As in the whole world, research studies on carbon capture continue in our country.