Carbon Capture and Storage (CCS) is a process of capturing carbon dioxide (CO2) from the combustion or burning of fossil fuels such as coal. Once captured, the gas is compressed and transported to locations with suitable geological formations for safe long-term storage (a process known as geosequestration).
Endorsed by G8 leaders, the International Energy Agency (IEA), the IPCC and The Stern Review, CCS has been identified as the foundation upon which the success of future deployment of contemporary clean coal technologies is contingent.
When applied to large point source emitters such as power plants, CCS is a three step process that involves:
1. CO2 Capture
The process of carbon capture produces a concentrated stream of CO2 that can be compressed, transported and eventually stored. Depending on the power plant, carbon capture can take place through:
Pre-combustion: a process that removes CO2 before it is burned as part of the gasification process.
Post-combustion: a process that removes CO2 with a solvent, strips off the CO2 with steam, and condenses the steam into a concentrated stream.
Oxyfuel combustion: a process that burns the fuel in pure or enriched oxygen to create a flue gas composed primarily of CO2 and water.
ZeroGen's power plant will utilise pre-combustion capture of CO2.
2. CO2 transport
Once CO2 has been captured, it needs to be transported to a storage location. Options for transportation include pipeline, ships, rail and road transport.
Transport of CO2 by pipeline is currently used in the United States where over 2500 kilometres of CO2 pipelines exist and carry 50 million tonnes of CO2 per year to enhanced oil recovery projects in Texas and elsewhere.
3. CO2 storage
The final step in the process is the safe and long-term storage of CO2. This can take place in either deep geological formations, under the ocean, depleted oil or gas fields, unmineable coal seams, or enhanced oil and gas recovery sites.
