How does carbon capture and storage work, and is it effective?
Technology that captures carbon dioxide from our atmosphere has existed for decades and is now being considered as a key method for fighting climate change.
In the spring Budget, £20 billion of funding has been announced to support carbon capture and storage projects around the UK. The Treasury said the package will help decarbonise our economy, maximise economic opportunities and help the UK reach its net zero target by 2050.
Here’s what you need to know about how carbon capture and storage works.
How does carbon capture work?
Carbon capture and storage (CCS) technology is a form of carbon sequestration that is set to play a central role in reaching net zero by 2050. Existing strategies to tackle climate change focus mainly on eliminating the carbon emissions from processes such as power generation or transport. However, carbon capture and storage takes CO2 directly from the atmosphere or at point of emission, and stores it safely within the natural environment.
How does carbon capture technology work?
Carbon capture and storage takes two basic forms:
Biological carbon capture and storage: when the natural environment – such as forests and oceans – sequesters CO2 from the atmosphere.
Artificial/geological carbon capture and storage: when CO2 as an emission is extracted from human-made processes and is stored in vast underground facilities.
Biological carbon capture and storage happens on a much larger scale than geological carbon capture and storage but the technology to stimulate both has traditionally been viewed as expensive and impractical at scale. This is changing, however, as investment and research into carbon capturing technologies takes off.
Carbon sinks are natural forms of carbon capture and storage, and are huge spaces where the natural habitats capture CO2 from the atmosphere. They include forests, oceans, grasslands and wetlands. Scientists recognise that the preservation and cultivation of carbon sinks could increase the amount of carbon taken from our atmosphere in the shortest space of time. In particular, coastal wetlands store more carbon per hectare than other habitats like forests.
Then there are deep saline aquifers, which are underground geological formations; they are vast expanses of porous, sedimentary rock, which are filled with salt water. CO2 can be injected into these and stored permanently – in fact, saline aquifers have the largest identified storage potential among all other forms of engineered carbon capture and storage.
The Endurance aquifer, located in the North Sea off the coast of the UK, is one such formation, which is approximately 1.6km below the sea bed. It allows carbon dioxide to be injected into it and stored safely for up to thousands of years.
In China companies have developed experimental commercial air filters, which are huge towers that clean air of pollutants on a vast scale. These giant air towers purify air by drawing it into glass rooms, which are heated using solar power 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 clean air.
Manufacturers believe they are close to developing even larger towers, where just one could clean enough air on a daily basis for a small city.
The most recent advancements in carbon capture and storage technology includes new types of liquids, which are highly effective at absorbing CO2.
In Denmark, Project Greensand is the first venture to achieve cross-border carbon capture and storage, by shipping CO2 from Belgium and injecting it into a depleted oil field below the Danish North Sea.
The project aims to safely and permanently store up to eight million tonnes of CO2 every year by 2030, which is the equivalent of 40 per cent of Denmark’s emission reduction target and more than 10 per cent of the country’s annual emissions.
Is carbon capture effective?
According to the World Economic Forum, the future of carbon capture looks promising. It said it will play an important role in the energy transition, especially in heavy industries such as power, steel, cement and oil and gas.
However, it is expensive and needs to be used widely in order to be effective – and it should not be used as a substitute for releasing more carbon into the atmosphere.