What is carbon capture and storage, and could it help halt the climate crisis?

Scientists say capturing greenhouse gas emissions at source or drawing them out of the air is vital, but must occur alongside shifts to renewable energy and making deep emissions cuts

The ‘Orca’ carbon capture project in Iceland injects CO2 deep underground where it turns to stone (Sigurður Ólafur Sigurðsson)

The United Nations’ Intergovernmental Panel on Climate Change is at it again – warning the world to mend its polluting, climate-altering ways.

The report, which is expected Monday, is the third installment of the most definitive global assessment on climate change, agreed by scientists and governments.

While the last two assessments looked at causes and impacts of the climate crisis, this one examines all of the various things our species can do to rein in the damage.

The core aspect of this is a dissection of how humanity could slash emissions of greenhouse gases, with an additional focus on ways of removing these pollutants from our atmosphere.

There are two main methods of achieving this.

Through natural processes – in which ecosystems such as soils, forests, sea grasses and peat bogs are allowed to recover from the damage we are doing to them, and can then draw down and store the gases – and also through new technologies which capture emissions.

These new technologies fall into two broad camps. Firstly, through catching concentrated industrial emissions at their source, preventing them from entering the atmosphere at all. This is usually known as carbon capture and storage (CCS).

And secondly, through technologies which suck greenhouse gas emissions directly out of the air, removing them at very low concentrations. This is usually known as greenhouse gas removal (GGR) or carbon dioxide removal (CDR).

There is a consensus that investing and utilising these technologies needs to be rapidly scaled up to have the impact required to keep the targets of the Paris climate agreement in sight - and prevent average temperatures rising 1.5C above what they were in the pre-industrial era.

But there are also widely-held concerns that industries and processes which already emit greenhouse gases could, or already are, using the burgeoning technology as a kind of get-out-of-jail-free card, in which they pin their future carbon reduction targets on installing or investing in GGR or CCS technology.

According to the International Energy Agency the strengthening of climate goals and new investment incentives "are delivering unprecedented momentum for CCS, with plans for more than 100 new facilities announced in 2021".

The agency said these technologies "will play an important role in meeting net zero targets, including as one of few solutions to tackle emissions from heavy industry and to remove carbon from the atmosphere".

But despite being "encouraging", the numbers of projects in the offing are inadequate and "fall well short of delivering the 1.7 billion tonnes of CO2 capture capacity deployed by 2030 in the net zero by 2050 scenario", the IEA said.

Professor Richard Templar, director of innovation at the Grantham Institute for climate change and the environment at Imperial College London, told The Independent new technologies have a long way to go, but he emphasised the important role they will play.

He said: "So far CCS and GGR have contributed very little indeed to tackling climate change. There are a small number of demonstrators for both technologies around the globe, testing the techniques, and informing future development of the approaches.

"In principle CCS and GGR could make significant contributions to tackling climate change, but we should have been developing these techniques with greater intent 10-20 years ago."

His colleague at Imperial, Dr Piera Patrizio, a research associate at the university’s Centre for Environmental Policy, told The Independent: "CCS is currently underused globally. Just 0.1 per cent of all global emissions are currently captured and stored, and researchers argue that CCS must be rapidly scaled up to mitigate emissions from energy intensive sectors."

She said the effectiveness of the technology had long been proven, pointing out that "in North America several thousand miles of high-pressure CO2 pipeline have been transporting millions of tonnes of CO2 since the 1970s," and that "geological storage has been safely operated in the North Sea by Norway for 20 years".

In both CCS and GGR techniques the CO2 is separated and captured from either the gases generated by a manufacturing process or from the gases in our atmosphere.

This CO2 must then be permanently stored deep underground, where it will mineralise - turn into rock.

An example of this process already successfully in operation is in Iceland, where the world’s largest "direct air-capture" machine, called Orca, takes carbon from the air and turns it into stone in just two years.

According to geological surveys there is plenty of subterranean capacity for injecting carbon, so the limiting factor is the manufacture and operation of such technology.

Even though it is the biggest in the world, Iceland’s Orca machine is capable of sucking up just 4,000 tonnes of CO2 a year – a tiny fraction of global emissions, which totalled 31.5 billion tonnes in 2020.

But experts say incentives must be put in place to expand this kind of technology, as the rate at which humans are causing emissions goes far beyond what can be absorbed through natural processes.

Dr Tilly Collins, a deputy director at the centre for environmental policy at Imperial College London, told The Independent: "A multifaceted approach [including new technology] is critical to addressing climate change as the carbon we have released over the past 150 years exceeds that which biological systems can absorb over the urgent timescale we face.

“Improving biological carbon absorption and storage through planting forests, improving grasslands, and restoring peatlands will also contribute and have the additional benefit of being potential win-wins by supporting biodiversity."

She also said long-term lock-downs of carbon from forest expansions will be enhanced by the growth in timber technologies for building and use as renewable feedstocks for chemical industries.

The IPCC’s report is expected to make a powerful case for strengthening measures to slash emissions from all sources, while also putting forward the best use of technology to remove pollutants.

How this is then interpreted by governments and organisations with historic connections to emissions-intensive commerce and industry remains a significant concern.

Professor Templar said: "We are in the midst of humanity’s biggest, self-inflicted challenge – the most rapid heating that the planet has ever experienced.

"We know that in order to cool the planet down we need to do two things. First and foremost to stop putting greenhouse gases into the atmosphere. Second, to remove CO2 already in the atmosphere and any that we really cannot help releasing. The avoidance of emissions is the single most important thing we need to do, but we now cannot avoid the need to also remove CO2 from the atmosphere. We need both."

But he warned: "The great danger is that some industries will not innovate and reduce emissions and simply rely on CCS and GGR as a solution. This would be reckless. The techniques are young and not yet scaled up. We need to accelerate their development so that we can start removal at significant levels by the 2030s.

"Renewable energy is here now. Being more energy efficient is here now. We need to transition to renewables and greater energy efficiency much faster than we are, because we have much of what we need to hand and we know it works."