What is carbon capture? Inside the tech that sucks CO2 underground

What is carbon capture? How the UK government plans to slash the amount of CO2 being released into the atmosphere by catching it and storing it under the North Sea

  • Carbon capture technology doesn’t divert the energy mix away from fossil fuels
  • READ MORE: Ministers commit to pouring £20billion into green carbon capture

It has been billed as an innovative way to allow Britain to slash its greenhouse gas emissions.

But what exactly is carbon capture and just how effective can it be?

Prime Minister Rishi Sunak is certainly a believer, having announced that two carbon capture and storage facilities will be built as part of a £20billion investment to curb the UK’s carbon footprint.

But many opponents are skeptical of what they say is a ‘fledgling science’ that is still in its infancy and has not been scaled up to prove exactly how much carbon it can stop entering the Earth’s atmosphere. 

Here MailOnline takes a closer look at how carbon capture and storage actually works and why it is so controversial. 

CCS is a technology designed to capture carbon emissions from power plants, industrial processes and other sources, and store them permanently underground

READ MORE: Ministers commit £20billion into green carbon capture

Prime Minister Rishi Sunak has been criticised for ‘championing more costly and dirty fossil fuels’ by embracing CCS


Carbon capture and storage (CCS) is a relatively new technology that could greatly reduce carbon emissions and in turn combat global warming. 

The technology is designed to capture carbon dioxide (CO2) emissions and store them permanently underground, as a greener alternative to releasing them into the atmosphere. 

According to the government, a CSS plant could potentially store a total of 78 billion tonnes of carbon – the same weight as 15 billion elephants. 

Different options to try to reduce overall CO2 emissions are being investigated, but CCS is the main way to reduce CO2 emissions from large industrial sources.  


When fossil fuels are burned they produce carbon dioxide – a greenhouse gas that contributes to global warming.

CCS therefore involves capturing the waste gases right at the source of their creation – such as power plants and industrial facilities that make steel and cement.

CCS facilities typically consist of a stack of metal ‘air scrubbers’, which suck in CO2 from surrounding ambient air using fans before extracting it using a chemical filter. 

CCS facilities typically consist of a stack of metal ‘air scrubbers’, which suck in CO2 from surrounding ambient air using fans before extracting it using a chemical filter. Pictured, a carbon removal facility from Carbon Engineering, a Canadian-based clean energy company

CCUS involves the capture of CO2, generally from large point sources like power generation or industrial facilities that use fossil fuels (file photo)

UK carbon capture plants in development 

– Acorn (Scotland)

– Viking (Humber)

–  HyNet (Liverpool/North Wales)

– East Coast Cluster (Teesside and Humber)

Once extracted, the CO2 is transported to a storage site via pipelines, or, often when the storage site is far away, by road vehicles or ships. 

The storage site is usually an underground cavern, like a depleted oil or gas reservoir, or a formation of porous rocks that have good gas storage potential, known as a saline aquifer. 

The carbon dioxide is then left there permanently, but is monitored to ensure it remains safely contained and is not prone to leakages. 

Another slightly different process known as ‘carbon capture, utilisation and storage’ (CCUS) involves reusing the CO2 in industrial processes by converting it into plastics, concrete or biofuel, for example. 


CCS has been criticised for encouraging continued use of carbon-belching fossil fuels rather than switching to renewable sources of energy. 

Mike Childs, head of policy at environmental organisation Friends of the Earth, said the government is just ‘championing more costly and dirty fossil fuels’. 

‘Talking up carbon capture and storage is an obvious attempt to put a green gloss on the prime minister’s announcement,’ he said.

Prime Minister Rishi Sunak is pictured on Monday during a visit to Shell St Fergus Gas Plant in Peterhead, Aberdeenshire. The Scottish government is committed to the Acorn carbon capture and storage (CCS) project despite controversies and doubts about the technology 

‘Even if it ever worked, which is unlikely in the near term, CCS won’t capture all the climate pollution caused by burning fossil fuels or address the significant emissions that are created when gas and oil is extracted.’ 

The technology also has safety concerns – after being stored underground, some experts fear that CO2 could leak and taint nearby water supplies or create tremors caused by the build-up of pressure underground. 

The long-term effects that the carbon dioxide and the pipelines that transport it may have on the environment are also not yet fully understood. 

What’s more, separating and storing the carbon dioxide is an energy intensive process in itself, so could reduce the efficiency of power plants. 


CCS has been in operation since 1972 in the US, where several natural gas plants in Texas have captured and stored more than 200 million tons of CO2 underground. 

According to the Global CCS Institute’s 2022 report, there were 194 large-scale CCS facilities globally at the end of the year, 80 of which are in the US. 

The UK is still waiting for its first CCS facility, although a plant that makes use of emitted CO2 rather than storing it (a CCUS) was opened in Cheshire last year. 

In June last year, a CCUS facility was opened in Northwich, Cheshire, said to remove up to 40,000 tonnes of CO2 each year 

Liquid carbon dioxide is stored in these units before being turned into sodium bicarbonate

At the facility, CO2 is captured from the ducts of a methane gas-fired power plant also located at the facility, before being purified, cooled and liquefied. 

It uses a patented process to turn the purified CO2 into sodium bicarbonate, a compound used to make baking powder and pharmaceutical tablets.


As part of the prime minister’s £20 billion round of funding for green carbon capture schemes, the newly confirmed CCS facilities will be opened in Scotland and the Humber.

Sunak has greenlit backing for the ‘Acorn’ project in Scotland’s north east ahead of a visit to Aberdeenshire, along with the Viking project in Yorkshire.

They are the third and fourth CCS facilities to be confirmed, following earlier backing of HyNet in the North Wales region and East Coast Cluster in the Humber and Teesside regions. 

Locations of CCS projects currently in development in the UK

The Government hopes HyNet and East Coast Cluster will be deployed by the mid-2020s, while Acorn and Viking will follow by 2030.  

The plants are situated near the coastline so that the captured CO2 will be transported for storage under the sea nearby. 

The Government has also announced that around 100 new oil and gas licenses will be granted in the North Sea, to boost domestic production of oil and gas. 

These essentially give companies permission to potentially extract oil and gas from new locations offshore – leading to criticism from some experts.

Stuart Haszeldine, a professor of carbon capture and storage at the University of Edinburgh, called it ‘a deal with the devil’. 

‘It’s essential to ensure that this carbon storage with Acorn or Viking projects provide a genuine decrease of emissions,’ he said.

‘Storage of 2 or 5 million tonnes CO2 per year should not become a policy excuse to release additional 10s or 100s million tonnes CO2 from development of new oil and gas extraction through many tens of new licences.’ 

Fossil fuels versus renewable energy sources

Renewable sources:

Solar – light and heat from the sun. 

Wind – through wind turbines to turn electric generators

Hydro – captured from falling or fast-running water

Tidal – energy from the rise and fall of sea levels

Geothermal – energy generated and stored in the Earth

Biomass – organic material burnt to release stored energy from the sun

Although nuclear energy is considered clean energy its inclusion in the renewable energy list is a subject of major debate.

Nuclear energy itself is a renewable energy source. But the material used in nuclear power plants – uranium – is a non-renewable.

Fossil fuels

Renewables contrast with the more harmful fossil fuels – oilcoal and gas.

They are considered fossil fuels because they were formed from the fossilised, buried remains of plants and animals that lived millions of years ago. 

Because of their origins, fossil fuels have a high carbon content, but when they are burned, they release large amounts of carbon dioxide, a greenhouse gas, into the air. 

Source:  EDF Energy /Stanford University

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