Carbon capture technology and how it works

Types of carbon capture technology

1. Carbon sink

Natural forms of CCS are called ‘carbon sinks’ and are vast spaces where natural habitats capture CO2 from the atmosphere – these include forests, oceans, grasslands and wetlands.

Scientists, as well as environmental and conservation experts, agree that conservation and cultivation of carbon sinks can increase the amount of carbon removed from our atmosphere in the shortest amount of time.

Grasslands and wetlands in particular have a much faster carbon storage turnaround, with coastal wetlands storing more carbon per hectare than other habitats such as forests.1

Where forest land is used, experts believe that certain types of trees – such as birch or willow – are optimal for sequestering carbon in the soil, as they absorb more CO2 compared to other types of trees.

Carbon dioxide storage in an ancient peat bog

One way we are working to capture carbon biologically is conserving and rehabilitating an ancient peat bog located close to one of our substations in South Wales.

The 15-hectare marsh stores the equivalent of 32,000 tonnes of carbon dioxide, which is equivalent to the average annual emissions of 22,000 petrol cars. Its restoration has also provided conditions for the flourishing of rare butterflies and vegetation.

2. Saline aquifers

Deep saline aquifers are underground geological formations; large expanses of porous sedimentary rock, filled with salt water. Co.2 can be injected into them and stored forever – in fact, saline aquifers have the greatest storage potential identified among all other forms of engineered CCS.

The ‘Endurance’ aquifer, located in the North Sea off the coast of the UK, is one such formation, which lies approximately 1 mile (1.6 km) below the seabed. About the size of Manhattan Island and the height of The Shard or the Empire State Building, its porous composition allows carbon dioxide to be injected into it and stored safely for potentially thousands of years.

In the US, many large-scale saline aquifers are now being used for CCS purposes, such as The Citronelle Project in Alabama. During its three-year trial period, it was successful in storing more than 150,000 tons of CO2 per year, which was captured from a nearby pilot facility.

3. Giant air filters

Carbon capture technologies are still being developed globally, with individual countries creating strategies that respond to their net zero goals. For example, in China companies have developed experimental commercial air filters – large towers that clean the air of pollutants on a large scale. These giant air towers purify the air by drawing it into glass chambers, which are heated using solar energy creating a greenhouse effect. This hot air is pushed up the tower through a series of filters, before being released back into the atmosphere as fresh air.

One such giant air purification tower in Xian is said to have cleaned more than 353 million cubic meters of air every day, dramatically improving local air quality. Manufacturers believe they are close to developing even larger towers, where just one can clean enough air on a daily basis for a small city.

4. Ionic liquids: a carbon capture technology of the future?

The latest advances in CCS technology include new types of fluids that are very effective at absorbing CO2. Two-dimensional “ionic” liquids have a molecular structure that allows for higher CO rates2 to be absorbed. Scientists believe that ‘editing’ fluids can provide more precise control in the chemical engineering process and are considered environmentally friendly.

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