Carbon Capture Storage (CCS) is an integrated set of technologies that prevent carbon dioxide from being released into the atmosphere during the combustion of fossil fuels. It is mainly mentioned in the context of large power plants running on coal, gas or biomass.
There are three main steps to avoid CO2 escaping into the air:
- Seperate the carbon dioxide from the other exhaust gases
- Compress and transport the CO2 via pipelines to a suitable site for geological storage, typically salt caves, old mines etc
- Inject the CO2 deep underground, often at depths of more than one kilometer
Graphical representation of the Carbon Capture and Storage process (graph: University of Nottingham)
CCS is not a new technology and has been applied since the mid nineties, although the amount of CO2 captured and stored remains marginal.
Carbon Capture and Storage got renewed attention when the IPCC’s latest progress report (fall of 2014) announced that the technology was crucial if we want to limit Earth’s temperature rise below 2°C by 2100. They estimated that big emissions cuts would cost more than double when not applying CCS technologies.
Although some say that CCS will allow us to keep consuming fossil fuels at an increasing rate, that is not really true. The processes itself are energy intensive so the overall efficiency of the energy generation process including the carbon capture goes down significantly. In addition, there are concerns regarding the long-term storability and possible leakage of the CO2 out of the caves and rock formations.