What is CCS?

There is global agreement to reduce emissions and limit increases in temperatures to two degrees celsius by 2100, with the need to stem the peak in emissions as soon as possible.
What is carbon capture and storage?

Global energy demand will rapidly grow into the foreseeable future. Even with significant reductions in fossil fuel reliance, commitments to a two degree emissions limit cannot be met unless the fossil fuels we continue to use are properly abated.

Emissions reduction will require a full suite of responses: increased use of renewable energy, greater energy efficiency, fuel switching, and the use of carbon capture and storage as the major technology to curb industrial emissions.

Carbon capture and storage (CCS) uses a group of known technologies to capture, transport and store carbon emissions from fossil fuel power plants and energy intensive industries like cement, steel and chemical production.

The International Energy Agency (IEA) states that CCS could reduce global carbon dioxide emissions by 13%, and that fighting climate change could cost 70% more without CCS.

 

How does it work?

Emissions are separated from industrial processes through solvent or membrane technologies that capture the carbon dioxide (CO2). The CO2 is then cooled and compressed to where it can be efficiently transported, either by pipeline or other means.

The CO2 is then injected deep underground into a specifically mapped geological formation, where the carbon will settle and remain for 1000 a years or longer. Read more on this process here. To provide ongoing assurance to the community that the CO2 remains where it is expected, it is monitored as part of the storage program.

The technologies involved in CCS are not inherently new having been applied in various forms for decades in the oil and gas industry, however their application to emissions reduction is relatively recent.

 

Why is carbon capture and storage needed?

The IEA state that the level of fossil fuel energy in the global energy mix in 2013 was 81%. To keep global temperature rise below 2oC this will need to decrease to 40% of primary energy use by 2050. This will require 95% of coal fired power plants and 40% of gas fired power plants to be equipped with CCS.

A mix of carbon reduction technologies is required to reduce global emissions.

CCS is not just limited to power generation, but can be applied to other industrial sources, such as natural gas processing, fertiliser production, hydrogen production, and iron, steel and cement making. The carbon emissions of industrial processes are around a quarter of global carbon emissions. There is also the potential to apply CCS to bio-fuel generation to achieve negative emissions.

Carbon Capture & Storage

Capture

The first step in carbon capture and storage (CCS) is separating the carbon dioxide from other gases in the exhaust stream and, in the process, capturing the carbon dioxide (CO2).

CO2 capture can be applied to industrial sources of CO2, using a variety of CO2 capture technologies.  Industrial processes such as the manufacture of some fertilisers, natural-gas processing  and cement manufacturing are all industries that could lower their CO2 emissions with carbon capture technologies.

Most of modern industrial society’s emissions of carbon dioxide come from fossil fuel-fired power stations, which can have flue-gas carbon-dioxide concentrations as low as 10 to 15 per cent. Separating such low concentrations of carbon dioxide from an exhaust stream is a complex and, with today’s technology, expensive process. CO2CRC is conducting extensive research into CO2 capture technologies to reduce this cost.

Transport

Unless the source of separated carbon dioxide lies directly above or next to a site for injection, it is necessary to transport the carbon dioxide to the site, usually by pipeline, although ships could in some circumstances be used for large distances.

Road transport is another option of smaller quantities of CO2. 110 tonnes CO2  was captured from Callide Oxyfuel Services Pty Ltd’s (COPL) Callide A Oxyfuel project in Queensland and transported by road to the CO2CRC Otway Research Facility in Victoria and stored in the subsurface.

The carbon dioxide will normally be compressed to a supercritical state (a temperature and pressure at which it shows properties of both liquids and gases) before transport. Because of its potential corrosive effects, water (and possibly some contaminants) is removed before transport.

Storage

Carbon dioxide can be stored geologically:

  • in depleted oil and gas reservoirs,
  • in deep saline formations, both offshore and onshore,

The main geological conditions required for secure storage of carbon dioxide are:

  • reservoir rock which is both porous (having pore spaces in which carbon dioxide can reside) and permeable (having links between pore spaces allowing the carbon dioxide to permeate through the rock)
  • a trapping mechanism, to stop the carbon dioxide migrating outside the target geological feature
  • an impermeable caprock to stop the carbon dioxide migrating upwards

Studies have shown that around the world there is enough geological storage for hundreds of years of global carbon dioxide emissions.