The controlled production of brine from rocks deep beneath the North Sea can greatly increase the amount of carbon dioxide (CO₂) that can be injected for storage and help to reduce the cost per tonne of tackling the UK’s carbon emissions, according to new research.
A multi-disciplinary project, funded by the Energy Technologies Institute (ETI), has studied how brine production, more often associated with oil and gas operations, can enhance the storage potential of saline aquifers already identified as ideal CO₂ stores.
The project findings, which will be presented at All-Energy 2017 on Thursday 11 May, also highlight other key benefits of using brine production alongside CO₂ storage, including the opportunity to convert smaller aquifers into economically viable stores. It may also give certain storage sites a longer lifespan by allowing operators to increase the injection rate at a later date as new CO₂ sources come on stream.
The project team was led by Scottish Carbon Capture & Storage (SCCS) partner, Heriot-Watt University, and included researchers from energy consultancy, Element Energy, along with scientists and engineers from Durham University and T2 Petroleum.
The UK has some of the world’s best geological CO₂ storage, up to 2.5km below the North Sea, which can be utilised in carbon capture and storage (CCS) projects to help the UK meet legally binding carbon targets. These storage sites have already been identified by CO₂Stored, the UK's offshore storage atlas, which led from the ETI’s UK Storage Appraisal Project.
Professor Eric Mackay, of Heriot-Watt University and principal investigator on the project, said:
We studied a set of potential CO₂ stores, identified from the UK’s offshore storage atlas, to assess the value of brine production in terms of both increasing CO₂ storage capacity and bringing down the unit cost of storage. Our findings suggest an eightfold increase in capacity is possible, plus a host of other benefits for a developing CCS industry in the UK.
Emrah Durusut, of Element Energy, said:
Our study has identified a variety of strategic benefits of brine production for both policymakers and storage operators. In addition to increasing storage capacity and achieving lower minimum unit costs at certain aquifers, brine production can also increase optionality for storage operators and allow operators to better utilise their existing storage assets within a defined licence area.
The project recommends further work that would support the development of CCS in the UK, including an assessment of how much economic value brine production would bring when CO₂ stores are handed over to a “competent authority” for longer-term operations and/or monitoring. A full report on findings will be released by the ETI later this year.