Why carbon capture still has a long way to go

Rising to a height of 4,169 metres, Hawaii’s Mauna Loa is the largest active volcano on Earth. It is also home to a research facility that provides valuable insight into climate change. Since 1958, the Mauna Loa Observatory has been monitoring changes to the Earth’s atmosphere, particularly levels of carbon dioxide.

It will come as no surprise to read that the ratio of CO2 in our atmosphere, measured in parts per million, has been rising rapidly over the last century, particularly in the last 50 years. In 2021, it reached an average of almost 415 parts per million. Scientists believe around 350 parts per million (last seen in the mid-1980s) is what we should be aiming for.

This means that simply ending emissions won’t be enough to stabilise our climate – we have now reached the stage where we need to remove CO2 from the air.

The most efficient way to do this is directly at source in industrial processes as the CO2 is much more concentrated. Carbon dioxide can also be extracted from air, but it is far less effective. Then there are two options: one is to ‘bury’ CO2 deep underground, known as carbon capture and storage (CCS); the alternative is carbon capture and utilisation (CCU), which involves ‘recycling’ CO2. In reality, we’ll need both – in addition to restoring natural carbon capture solutions such as forests and wetlands.

Unfortunately, CCU and CCS technologies are still in their infancy. And to complicate matters further, without a carbon tax, there is currently little financial incentive for companies to pursue CCS. The advantage with CCU is that the companies that capture carbon can then sell it for a range of industrial uses. The hope is that CCU will help scale up carbon capture technology and push its costs down so that it is ready when policymakers do decide to support CCS.

The aim of CCU is to convert CO2 into more valuable substances or products. It is typically captured via a chemical or physical separation process, then transported in ships and pipelines for further use.

These uses range from plastics and building materials to fertilisers and biofuel. Some use CO2 directly, without converting it, but some involve processing the CO2 chemically or biologically, which can be energy intensive. Indeed, one drawback with CCU is that most outcomes still emit some levels of carbon.

CCU has experienced several false starts over the last decade and a half. According to the International Energy Agency (IEA), the technology attracted a wave of hype and investment after the 2008-09 financial crisis, much of which went unfulfilled. The past decade has seen plenty of high-profile cancellations and government funding that failed to deliver. “Many CCU/S projects simply could not advance fast enough to meet near-term spending milestones required by stimulus programmes,” the IEA says.

Somewhat ironically, the only industrial CO2 use to reach any sort of scale in recent years is enhanced oil recovery. This involves injecting pressurised CO2 into oil and gas reservoirs to squeeze out more fossil fuel.

Regardless of how we reuse the CO2, CCU will never avoid the need to also store carbon. We simply emit too much.

Carbon capture and storage involves injecting CO2 into rocks a kilometre or more underground. These are covered by impermeable rocks that, in theory, prevent any CO2 leaking out into the atmosphere. If everything is done right, huge amounts of CO2 could be safely stored underground for thousands or potentially millions of years.

Currently, there are just a few dozen active CCS or CCU plants around the world. The technology is expensive and difficult to scale, which massively reduces its appeal. As Vox points out, clean tech like electric cars or solar power are well on the path to being cheaper and/or better than their fossil fuel counterparts, as well as more sustainable. The same cannot be said for carbon capture.  

If carbon capture is to make a serious dent in climate change, things need to change fast. The current annual carbon capture capacity is 40 megatonnes of CO2. This must increase to 1.6 billion tonnes in 2030 to align with a pathway to net zero by 2050, says the IEA.

But this could be a watershed period for carbon capture technologies. The IEA says more than 100 new CCUS facilities were announced in 2021 and the global project pipeline for carbon capture capacity is set to quadruple. There is undoubtedly still a long way to go, but this gives cause for optimism, the IEA says. “Governments, industry and investors alike now have a collective role and interest in ensuring this is the decade that CCUS delivers.”