Problems at two long-running Norwegian carbon capture and storage (CCS) projects are highlighting worrying challenges for the future, including the risk of creating a new fossil fuel subsidy.
Sleipner, which has been running since 1996, and Snøhvit, running since 2008, are held up as the success stories of CCS.
But Sleipner struggled with carbon dioxide unexpectedly migrating upwards by 220m from the original underground storage site, while Snøhvit saw storage capacity cut from an estimated 18 years to less than two once the operation was underway, according to a review of studies by Grant Hauber at IEEFA.
“Every project site has unique geology,” Hauber says.
“Subsurface conditions which exist at a given point on the Earth are specific to that place; even then, any information obtained about that place is only a snapshot in time. The Earth moves and strata can change.
“While the oil and gas industry is used to dealing with uncertainty in exploration and production, the risks multiply when trying to place something like CO2 back in the ground.”
Both facilities, run by Norwegian state-owned energy company Equinor ASA, compress carbon dioxide from the production of natural gas and reinject it underground.
Between them, the facilities handle an average of 1.8 million metric tonnes per year of CO2 with a total of 22 million tonnes in storage so far.
Geology can only tell us so much
Sleipner and Snøhvit are storage locations that are as well understood as subsurface techniques would allow, and came with a wealth of data. Yet there were still aspects of the geology that weren’t known until carbon dioxide was pumped in.
At Sleipner, a solid caprock is preventing the carbon dioxide from migrating further upwards but scientists do not know how far the containment goes. At Snøhvit, pressure rose quickly just two years after the site began to be used as the formation couldn’t accept carbon dioxide at levels the design studies suggested it could.
“Snøhvit highlights the need for CCS projects to have continuous monitoring, extensive backup plans and the money to implement them. Sleipner proves that injected CO2 can start behaving in unexpected ways despite what appears to have been years of nominal performance,” Hauber says.
With injection rates of 0.85mtpa-1.0mtpa and 0.7mtpa respectively, are also small compared to CCS projects that are underway or proposed around the world.
In Australia’s only current CCS project, Chevron has been trying, and failing, since 2019 to make its 3.5mtpa-4mtpa Gorgon CCS project to meet its target of 80 per cent carbon dioxide capture.
New fossil fuel subsidy
Hauber’s research not only indicates the level of regulatory oversight governments need to have over CCS storage sites, but casts doubt on whether the world has the technical prowess, regulatory strength, or the multi-decade commitment of capital and resources required to safely sequester carbon dioxide for the long term.
Because monitoring storage sites is a long-term, non-monetisable problem, there is a risk this process will fall to governments to handle long after the storage sites are shuttered.
“With the unknowns of long-term subsurface CO2 storage, regulators could inadvertently allow material risks to be transferred to the taxpayer,” Hauber says.
“Subsurface CO2 storage is an amalgamation of probabilities and risks, some of which can be identified, others remaining unknown until troubles materialise. These risks – and the costs that accompany them – are not being made part of public discourse by either industry or government.”
Furthermore, by encouraging new fossil fuel projects to launch by accepting CCS as a solution, governments are likely to be locking in extra new carbon dioxide emissions when the promise of CCS is far from absolute.
