Greenhouse gas emissions from an industrial plant. © Dudarev Mikhail -

Geological storage of CO2: european research in the frontline

The BRGM was recently selected as the coordinator of the European ENOS project, which aims to break through the scientific barriers to widespread onshore CO2 storage in Europe.

logo ENOS

To reach the CO2 emission reduction targets set out in the Paris Agreement, 12.2 billion tonnes of CO2 need to be stored in Europe by 2050.

"We will not be able to rely solely on storage capacities in the North Sea", explains Rowena Stead, who is a member of the CO2GeoNet association that initiated the project. "Geological storage sites for CO2 will also be needed onshore, close to the points of emission". Hence the ENOS project, which involves 29 European organisations from 17 countries, 19 being members of the Co2GeoNet network of excellence. ENOS is a 4-year project launched in late 2016 as part of the European Union's "Horizon 2020" programme, with a budget of 12.5 M€.

"The ENOS project aims to gain experience on the ground in deep aquifer storage in order to refine site selection methods and improve predictions and monitoring of site behaviour for better risk management".

Studies are planned on several demonstrators in the field, in different geological contexts. As ENOS coordinator Marie Gastine explains, "to remove the remaining barriers to safe and efficient injection, guarantee site security and verify storage capacities and possibilities for combining storage with the reuse of CO2 for economic activities, we have to conduct our studies in actual sites".

Full-scale tests

The injection wellhead at Hontomín with the CO2 pipeline to the left and the brine pipeline to the right

The injection wellhead at Hontomín with the CO2 pipeline to the left and the brine pipeline to the right. © BRGM

Several sites have been selected, including Hontomín in Spain, where the BRGM recently developed a range of electrical and electromagnetic surveillance systems for Europe's only operational onshore CO2 storage pilot (ANR EM-Hontomín project).

"At the site, we will be injecting 10 000 tonnes of CO2 into a carbonated reservoir 1 500 m below the surface, in order to identify optimum parameters to monitor the reservoir and ensure effective CO2 storage management with no risks to the environment", explains Marie Gastine.

Innovative injection strategies will also be tested: injection under intermittent flow conditions, variable injection temperatures and injection of CO2 dissolved in water.

The behaviour of CO2 in the event of leakage will be studied at the in situ Geoenergy Testbed laboratory in Nottingham (UK) and at the Sulcis Fault Lab in Sardinia.

"We will be simulating a leak 200 m below the surface in two different geological contexts, one in the UK in a near-surface aquifer, and the other along a fault, in Sardinia. The study results will be used to validate consistency between predictions and measurements and the suitability of the leak detection tools." says Marie Gastine.

Beside coordinating the programme, the BRGM is involved in other aspects : development of a sampling probe, geochemical modelling work, risk assessment methodology, drinking water protection, testing an optical leak detector, assessing storage capacities, training and interaction with neighbouring communities.

"Thanks to CO2GeoNet, ENOS is maximising its impact in Europe", concludes Rowena Stead, "and is now planning to develop new pilot sites, produce recommendations for operators and the public authorities and train future experts in underground CO2 storage."

Output from an electromagnetic survey at Hontomín. © BRGM

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