Carbon capture: Why it's time to invest more in storing CO2

BY STEVE RANGER |

Current assumptions about how much CO₂ can be stored underground using carbon capture technologies may be overly optimistic, unless there is more investment in the sector.

Researchers at Imperial College London, UK, have calculated how quickly it is possible to scale up the carbon capture and storage (CCS) technologies needed to store gigatonnes of CO₂ underground. The researchers suggest that much more investment is needed, if CCS is to have the impact of climate change that its supporters hope it can deliver.

Scenarios for limiting global warming to less than 1.5oC by the end of the century in part rely on CCS technologies that remove CO₂ from the atmosphere. It’s going to need massive effort: this future CO₂ storage industry will be comparable to the current scale of the oil industry, which produces around 4Gt of oil annually.

But estimates of how quickly CCS technology can be deployed have been ‘highly speculative’, according to the researchers. Their study shows existing storage projections are unlikely to be feasible at the current rate of growth.

They point out that deployment of CCS has already fallen short even of near-term projections: around 70% of the 149 projects proposed to be operational by 2020 – aiming to store 130Mt of CO₂ annually – were not implemented.

Project cost, immature technology and a lack of revenue streams were among the main reasons projects stopped.

‘This discrepancy between real-world development and projected trajectories highlights limitations to CO₂ storage scale-up that are not captured by existing integrated assessment models,’ they warn.

The study calculated that it might be possible by 2050 to store up to 16Gt of CO₂ underground each year. However, reaching this target would require a ‘huge’ increase in storage capacity and scaling over the coming decades, which is not currently expected given the current pace of investment. The researchers note there is no current business or political framework under which this scale of industry would operate: for example, in that scenario the US would have to store a ‘majority percentage’ of its current CO₂ emissions, which would require major cross-border transport of CO₂.

The team’s calculations suggest that a more realistic global benchmark is in the range of 5 to 6Gt of storage per year by 2050. This estimate aligns with how existing, similar technologies have been scaled up over time: the modelling uses growth patterns observed in industries including mining and renewable energy.

While the results suggest it is possible to reduce CO₂ emissions at a huge scale, it also means significant additional investment will be needed.

Co-author Samuel Krevor from Imperial’s Department of Earth Science and Engineering, said: ‘Although storing between six to 16Gt of CO₂/year to tackle climate change is technically possible, these high projections are much more uncertain than lower ones. This is because there are no existing plans from governments or international agreements to support such a large-scale effort.’

‘However, it’s important to keep in mind that 5Gt of carbon going into the ground is still a major contribution to climate change mitigation.’

Greg Mutch, Royal Academy of Engineering Research Fellow, Newcastle University, said these results should act as a warning that current projections for deployment of CO₂ storage have been overly-optimistic. Mutch said we should adjust our expectations for its contribution in the short- to medium-term.

‘This is not to say that CO₂ storage cannot contribute as expected in the long-term; it is that we are not on track for it to do so as fast as we had assumed,’ he said. The results should act as a stimulus to increase investment in, and deployment of, CO₂ storage, ‘particularly in the UK where we are uniquely well-equipped to do so in terms of geology, skills, and expertise,’ he added.

Jonathan Gibbins, professor of Carbon Capture at the University of Sheffield, UK, pointed out that the paper says ‘very useful amounts of CO₂ storage’ accounting for about 15% of current global CO₂ emissions can be in use by 2050 – but only if the world gets started soon and puts serious effort into its deployment.

‘Even while there is not enough time left now to reach the maximum technically possible CO₂ storage rates by 2050, the storage industry could expand by one or two orders of magnitude after 2050 if the need was there,’ he said.

But Alaa Al Khourdajie, a research fellow in the department of chemical engineering, Imperial College London, said that geological storage is just one aspect of CCS technologies. Capture, transport, and storage face unique scale-up challenges and these vary significantly across different industrial sectors and applications of CCS technologies, with power generation, cement production and steel manufacturing all presenting distinct technical and economic hurdles.