What is Carbon Capture? How the UK government plans to reduce the amount of CO2 released into the atmosphere by capturing and storing it under the North Sea

It has been heralded as an innovative way to enable Britain to reduce its greenhouse gas emissions.

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

Prime Minister Rishi Sunak is certainly a believer after announcing two carbon capture and storage facilities coming will be built as part of a £20 billion investment to reduce the UK’s carbon footprint.

But many detractors are skeptical of what they say is a “new science” that is still in its infancy and hasn’t been scaled up to prove exactly how much carbon it can stop from entering Earth’s atmosphere.

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

WHAT IS CARBON CAPTURE AND STORAGE?

Carbon capture and storage (CCS) is a relatively new technology that can significantly 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 store a total of 78 billion tons of carbon – the same weight as 15 billion elephants.

Several options are being explored to reduce overall CO2 emissions, but CCS is the main way to reduce CO2 emissions from major industrial sources.

HOW DOES IT WORK?

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

CCS therefore involves capturing the waste gases directly at the source of their origin, such as power plants and industrial facilities that make steel and cement.

CCS facilities typically consist of a stack of metal ‘air scrubbers’, which draw in CO2 from the surrounding ambient air using fans and then exhaust it with a chemical filter.

Once extracted, the CO2 is transported to a storage location via pipelines or, often if the storage location is far away, by road vehicle or ship.

The storage site is usually an underground cave, such as a depleted oil or gas reservoir, or a porous rock formation with good gas storage potential, known as a saline aquifer.

The carbon dioxide is left there permanently, but is monitored to ensure it is safely contained and not susceptible to leakage.

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

WHY IS CCS CONTROVERSIAL?

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

Mike Childs, policy chief at Friends of the Earth, said the government is just advocating more expensive and dirtier fossil fuels.

“Carbon capture and storage is an obvious attempt to add a green sheen to the Prime Minister’s announcement,” he said.

“Even if it did work some day, which is unlikely in the short term, CCS won’t capture all of the climate pollution caused by fossil fuel burning or address the significant emissions created when gas and oil are extracted.”

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

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

Moreover, separating and storing carbon dioxide is an energy-intensive process in itself, which can reduce the efficiency of power plants.

WHERE IS CCS ALREADY USED?

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

According to the The 2022 Global CCS Institute reportthere were 194 large-scale CCS facilities worldwide at the end of the year, 80 of which were in the US.

The UK is still waiting for its first CCS facility, although a factory opened in Cheshire last year that uses rather than stores emitted CO2 (a CCUS).

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 convert the purified CO2 into sodium bicarbonate, a compound used to make baking powder and pharmaceutical tablets.

WHERE ARE THE CCS INSTALLATIONS IN THE UK?

As part of the Prime Minister’s £20bn round of funding for green carbon capture schemes, the recently confirmed CCS facilities will open in Scotland and the Humber.

Sunak has been given the go-ahead for the ‘Acorn’ project in the North East of Scotland 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 previous support from HyNet in the North Wales region and East Coast Cluster in the Humber and Teesside regions.

The government hopes that HyNet and East Coast Cluster will be deployed by mid-2020, with Acorn and Viking following in 2030.

The installations are located close to the coast, so that the captured CO2 is transported for storage in the nearby sea.

The government has also announced that around 100 new oil and gas licenses will be issued in the North Sea to boost domestic oil and gas production.

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

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

“It is essential to ensure that this carbon storage with Acorn or Viking projects produces a real reduction in emissions,” he said.

‘Storage of 2 or 5 million tons of CO2 per year should not become a policy excuse to release another 10 or 100 million tons of CO2 through the development of new oil and gas extraction through dozens of new permits.’