Carbon Capture and Storage OR (Carbon Capture and Sequestration) (CCS)

CCS TECHNIQUE

What is CCS?

CCS, or Carbon Capture and Storage, is a working low carbon technology which captures carbon dioxide (CO₂) from the burning of coal and gas for power generation, and from the manufacturing of steel, cement and other industrial facilities, and transports it by either pipeline or ship, for safe and permanent underground storage, preventing it from entering the atmosphere and contributing to anthropogenic climate change.

How does CCS work?

There are three stages to CCS: capture, transport, and safe underground storage.

• Capture – First, the carbon dioxide is removed, or separated, from coal and gas power plants, and from the manufacturing of steel and cement. There are three types of capture; post-combustion, pre-combustion and oxyfuel combustion. This is called carbon dioxide capture and can captures 90% of carbon dioxide emissions.
• Transport – The carbon dioxide is then compressed and transported to a suitable storage site. The transport is generally carried out in pipelines. Ship transport is also an option for offshore carbon dioxide transport.
• Storage – The carbon dioxide is the injected into a suitable storage site deep below the ground. The storage site must be a geological formation that ensures safe and permanent storage. Storage can either take place in depleted oil & gas fields, or deep saline formations.

What is a CCS plant? What will it look like?

A CCS plant is one which captures carbon dioxide from the burning of fossil fuels at coal and gas power plants, and from steel and cement manufacturing plants It is a combination or three parts; capture, transport and storage of carbon dioxide. Depending on the location of the power plant or industrial facility, the carbon dioxide can be transported over long distance for storage.
CCS plants are typically situated next to the plant from which carbon dioxide is captured. A ‘capture-ready’ power plant is one that has been designed and built for subsequent retrofitting with CCS technology. This requires space to be set aside next to the power plant, as well as an identified pipeline route and storage formation.
A carbon dioxide pipeline supporting CCS will be very similar in design and scale to pipelines already employed for the transport of natural gas. The same regulations that are applied to all pipelines are applied to Carbon Dioxide ensuring high standards of design and protection of the pipeline and environment.

How does it work with coal and gas plants?

CCS removes or “captures” the carbon dioxide produced from coal or gas fired generation and transports it for safe underground storage. There are three ways capture can be done:

• Post-combustion capture

Carbon dioxide can be captured from the exhaust of a coal or gas power plant by absorbing it in a solvent. The absorbed carbon dioxide is removed from the solvent and then compressed for transport and safe underground storage. The solvent is recycled as part of an environmentally responsible process.

• Pre-combustion capture

The coal or gas is pre-treated and converted into a mix of hydrogen and carbon dioxide, with the carbon dioxide separated, compressed and transported for safe underground storage. The hydrogen produced can then be used as a zero-carbon fuel.

• “Oxy-fuel” combustion systems

The coal or gas is burned in oxygen instead of air, which then produces a more concentrated carbon dioxide stream for easier separation.

What is carbon dioxide?

Carbon dioxide (CO₂) is a naturally occurring gas, found in the atmosphere. Carbon dioxide is all around us. We breathe out carbon dioxide and it is a vital gas for plant life. Carbon Dioxide has been used on industrial sites and in food manufacturing for many decades, including in soft drinks and fire extinguishers.
We also emit carbon dioxide from power generation, driving cars, aviation and homes, all of which we need to tackle if we are to limit the effects of climate change.
Although carbon dioxide in the atmosphere is essential to maintain a climate habitable by people, too much carbon dioxide in the atmosphere can lead to potentially harmful climate change. Carbon dioxide is the most important anthropogenic greenhouse gas. According the IPCC, the global atmospheric concentration of carbon dioxide has increased from a pre-industrial value of about 280 parts per million (ppm) to 379 ppm in 2005. The atmospheric concentration of carbon dioxide in 2005 exceeds by far the natural range over the last 650,000 years (180 to 300 ppm) as determined from ice cores.
To limit average climate change to less than 2°C, the IPCC states that atmospheric carbon dioxide should be kept below 450ppm. Atmospheric carbon dioxide can also cause ocean acidification, which damages the marine ecosystem. This is why we are developing CCS - to limit the carbon dioxide from entering the atmosphere and causing climate change.

Is carbon dioxide dangerous?

Carbon dioxide (CO₂) is all around us. We breathe out carbon dioxide and it is a vital gas for plant life. Carbon dioxide has been used for many decades in industrial processes, in food manufacturing, including soft drinks, and is an essential component of other everyday items such as fire extinguishers.
In very high concentrations carbon dioxide can be dangerous to humans, having an adverse impact on respiration. Like any dense gas that can displace the air that we breathe, in very high concentrations carbon dioxide can act as an asphyxiant. Where carbon dioxide is handled in very high concentrations, regulations are in place to minimise risks to human health and the environment.
Exposure limits[1] set by the Health & Safety Executive (HSE, the UK regulator for health and safety) regulate exposure to carbon dioxide for workers in the same manner as other potentially hazardous substances.