Project Greensand aims to safely and permanently store up to 8M tonnes of CO2 per annum in the INEOS operated Siri area of the North Sea. The storage potential, if achieved, will contribute significantly to Denmark’s 2030 overall emissions reduction target. The Greensand project has three phases: Appraisal, Pilot (Proof of concept) and Full project execution. We are currently in the Pilot project phase.

A requirement for offshore CO2 storage is the ability to monitor and verify reservoir integrity during and after the initial storage activity, to satisfy regulatory requirements and to alleviate public concern around potential risks. NOC pioneered an approach to offshore CO2 storage monitoring in the recently-finished STEMM-CCS project ( Using novel chemical sensors developed at NOC (the “lab-on-chip” sensors), we showed that we could detect and quantify a deliberate, controlled release of CO2 in the North Sea, which mimicked a release from a CO2 injection process.

For Project Greensand NOC will develop the offshore CCS monitoring technology we developed in the STEMM-CSS project into a tool suitable for a longer-term real-world deployment. This is being achieved through designing and building a more robust CCS monitoring system. This includes developments of our carbonate sensors to make them suitable for longer-term use and development of a lander which will support NOC’s chemical monitoring system as well as acoustic instruments from the University of Southampton.



Contact: Allison Schaap

Email: allison.schaap(at)

Project Dates: 
January 2022 to December 2023

Denmark's Energy Technology Development and Demonstration Program