While carbon capture and storage (CCS) is not considered to be a major factor in meeting the world’s 2050 zero-carbon target, it can still have a significant impact. As a recent report from researchers at Imperial College, London, UK, has pointed out, its development can form a key component in keeping global warming to less than 2°C above pre-industrial levels by 2100 (Energy Enviro. Sci., doi: 10.1039/D0EE00674B).
The analysis suggests the amount of CO2 storage space required would actually be less than previous estimates by academia and industry groups of the levels currently available, believed to be around 10,000Gt globally. The Imperial College researchers estimate that 2,700Gt would be sufficient to meet the global warming targets of the Intergovernmental Panel on Climate Change (IPCC), although this figure could need to grow if the deployment of the technology is delayed.
They believe there has been an 8.6% increase in CCS over the 20 years, and that this growth is consistent with meeting the various climate change mitigation scenarios that include carbon capture. These scenarios also require the inclusion of renewable energy, improved energy efficiency and electrification of the transport sector. CCS alone will not be sufficient to solve the problem entirely, but storage faster and sooner than currently envisaged may help governments meet the most ambitious mitigation scenario targets.
As the study leader, Christopher Zahasky, who was in Imperial College’s Department of Earth Science and Engineering, but has since become an assistant professor at the University of Wisconsin-Madison, pointed out: ‘Nearly all IPCC pathways to limit warming to 2°C require tens of Giga tonnes of CO2 stored per year by mid-century. However, until now, we didn’t know if these targets were achievable given historic data, or how these targets related to subsurface storage space requirements.’
The co-author of the study, Samuel Krevor added: ‘Rather than focus our attention on looking at how much storage is available, we decided for the first time to evaluate how much subsurface storage resource is actually needed, and how quickly it must be developed to meet climate change mitigation targets.’
The storage requirement was determined by combining data on the past 20 years of CCS growth, information on historical rates of growth in energy infrastructure and models commonly used to monitor the depletion of natural resources.
The faster CO2 is stored, the less total subsurface storage resource is needed to meet storage targets. This is because it becomes harder to find new reservoirs or make further use of existing reservoirs as they become full.
In the UK, carbon capture and storage has had a fairly turbulent past with UK governments over the years that have first offered to fund projects and then at a later stage cancelling the funding.
The latest UK project is what has been described as part of the world’s first zero-carbon industrial hub around the River Humber. With a target date of 2040, the proposals include a demonstration hydrogen production facility to be built by 2025, to be followed, in 2027, by the installation of carbon capture equipment at one of the four biomass generating units at the Drax power station. The organisations involved in this project include Phillips 66, Uniper and the VPI Immingham plant owned by Vitol, as well as Associated British Ports, Saltend Cogeneration, Centrica Storage and National Grid Ventures.
But this not the only zero-carbon project currently under way in the UK. On Teeside, there is a project involving energy companies, including BP, Shell and Total as well as Eni and Equinor, with a heavy emphasis on carbon capture, utilisation and storage facilities. While on the other side of England, the North West Energy & Hydrogen Cluster, led by the University of Chester and the Manchester Metropolitan University, is also looking at carbon capture and hydrogen production.
The UK government’s commitment to totally decarbonising at least one industrial cluster by 2040 has spurred this competitive spirit, which also includes plans in Grangemouth in Scotland, North Wales and Southampton in southern England.
But as the Imperial College researchers have pointed out, CCS is not the whole story – renewable energy sources will be equally important. Approval has just been granted for the UK’s largest ever solar farm, scheduled to be onstream by April 2022. The £450m 350MW Cleve Hill project on the north Kent coast near Faversham will be five times larger than the current largest facility, Shotwick in north Wales, and will also incorporate what is described as one of the world’s largest storage batteries to help balance demand peaks.
And demand peaks, or rather the lack of them, has been a consistent feature of the current Covid-19 pandemic, with the National Grid reporting it may cost around £500m in payments to generators, including solar and wind farms, to maintain the electricity supply balance, as demand has fallen by up to 20%.