With COP27 now behind us and no significant changes to Nationally Determined Contributions (NDC) on offer (e.g. from China), various commentators are now remarking that meeting the goal of 1.5°C may be in doubt. This means passing the 500 Gt carbon budget that the IPCC linked to the 1.5°C goal.
Many recent IPCC scenarios also show 1.5°C being breached, but deploying removals later in the century to draw carbon dioxide out of the atmosphere is then used in the scenario to reverse the balance and at least meet the 1.5°C goal by 2100. In the IPCC Special Report on 1.5°C released in 2018, all four model pathways required some form of future removal, ranging from very little in P1 to significant in P4, depending on the lifestyle and transition pathway the particular scenario embraced and the level of overshoot of 1.5°C. Both nature based and technological removals are required. In the 2018 report technological removals were shown as bioenergy processing with carbon capture and storage (BECCS), but today we could realistically envisage both BECCS and direct air capture with CCS (DACCS) playing a role. The latter has advanced considerably in just five years.
So as well as requiring CCS to get to net-zero emissions, society will almost certainly have to consider removals as a technology to deliver negative emissions globally, i.e. after the goal of net-zero emissions is achieved. Large scale removals might also offer the much longer-term prospect (i.e. in the 22nd century) of winding the atmospheric carbon dioxide levels back towards pre-industrial levels.
While global net-negative emissions on a scale that shifts the atmospheric concentration of carbon dioxide is technically possible, the contrast with the very limited scale of deployment of BECCS and DACCS today seemingly takes the task into the realms of science fiction. Yet a century ago the scale on which energy is generated now would also have seemed like science fiction, so the task should not be dismissed. Nevertheless, the longer term could require these technologies and changes in land use to scale to many billions of tonnes of carbon dioxide removal per year. The question this poses is not whether it is possible, but how can it be made to happen.
Carbon capture and storage has become a commercially available technology over the past twenty years, yet global deployment remains very limited. The technology itself isn’t the issue, it is the lack of sustainable business models for deployment. There is a carbon price in Europe, but for many years it languished at just a few Euros and other similar systems currently operating throughout the world typically maintain prices at levels well below what is required for CCS and therefore, not surprisingly, well below the levels required for a 1.5°C transition. Bespoke CCS deployment policies are almost non-existent outside the United States. In the USA a specific tax-credit mechanism exists at the Federal level and the California Low Carbon Fuel Standard will allow the use of credits based on DACCS. As a result the USA is the global leader in CCS deployment and the pipeline of projects looks impressive, largely based on the revised tax credit available through the Inflation reduction Act. There are also DACCS projects emerging and a BECCS ethanol facility has operated in Illinois for some time now.
CCS requires a very long term business model, based on some form of market pull. Today the support for CCS comes largely from direct government grants and support mechanisms for early stage technology, but there is always a limit to such incentives. However, with net-zero emissions now becoming a clear goal in most energy system policy frameworks, a more sustainable model is likely to emerge as businesses seek to mitigate their own emissions, either due to direct policy requirements or indirect consumer preference for zero carbon emission goods and services. A balance will be found between the cost of new technologies such as green hydrogen for industry and making use of CCS in industries that continue to use fossil fuels. Society will find ways to absorb these costs over time as net-zero emissions is reached and whether this results in large or small scale deployment of CCS remains to be seen, depending on the relative costs between competing pathways.
But the next stage of the CCS journey, possibly commencing as early as the 2040s for some, will be to deliver net-negative emissions via DACCS and BECCS, i.e. drawdown of carbon dioxide from the atmosphere. While this may seem like a long way off, the history of creating basic CCS business models points to the need for an early start. The journey probably commences at the UNFCCC level, where a framework for net-negative emissions would need to be established including a global goal, some form of burden sharing agreement between nations and a discussion on the role of nature versus the role of technological drawdown solutions. Unfortunately, with history as a guide, this could take some time. But perhaps the bigger challenge will be for national governments to cascade the need into the economy and find ways to spread the cost of net-negative emissions across society within goods and services and even through taxation. This may not be popular given the net cost of the task, yet with no immediate tangible benefit. Imposing deep emission reduction goals is still proving to be a difficult task in some economies today, let alone asking the population to pay for atmospheric drawdown of carbon dioxide. However, the very long term benefit can be measured in practical terms, such as avoiding metres of sea level rise.
With the prospect of a 1.5°C overshoot scenario looking likely, future biological and geological storage of atmospheric carbon dioxide becomes essential. This task may lead to the development of huge industries engaged in such activities, or very little activity at all, depending on the policy frameworks and business models that emerge.