Carbon Sequestration
CCS Technology
Capturing and preventing the release of CO₂ into the atmosphere was first suggested in 1977. Carbon capture technologies have been used since the 1920s. The injection of CO₂ into underground reservoirs where it remains trapped for thousands of years works on a similar principle to how hydrocarbons are trapped and accumulate in oil reservoirs underground.
Since the early 1970s, CO₂ from gas processing has been captured for use in Enhanced Oil Recovery (EOR), a process developed to increase oil recovery from subsea reservoirs by injecting CO₂. This process has proven very successful, with 60-70% of the CO₂ remaining underground. Millions of tonnes of CO₂ are now injected into oil reservoirs globally every year.
The exemplar for commercial CO₂ injection is the Sleipner project in Norway (North Sea). Established in 1996, Sleipner was the world’s first commercial CO₂ storage project, storing gas captured from natural gas processing in an offshore, sub-surface geological formation (reservoir). In the 26 years since it became operational, the project has stored approximately 900,000 tonnes of CO₂ each year. A paper by Furre et al in 2017 reported that 3D seismic monitoring revealed no leakage of the sequestered CO₂ from the Sleipner reservoir. This has been confirmed by the Massachusetts Institute of Technology.
In 2021, the global capacity of CCS facilities was reported at 40Mtpa, with hundreds of new commercial facilities in development. Many more are needed to reach the 5,600 Mtpa of CO₂ storage required by 2050 to limit global warming to 2°C.
Injection into Offshore Saline Aquifers
Geo-sequestration in deep saline aquifers or depleted oil and gas reservoirs is a proven method for the permanent, safe storage of large volumes of CO₂.
Oil and gas fields have trapped hydrocarbons for many millions of years through the combination of an impervious top-seal and a suitable trapping mechanism. Injecting CO2 into a depleted oil and gas fields would therefore work on a similar principle to how the original hydrocarbons were trapped and accumulated. Essentially the depleted oil and gas filed is being repurpose for CO2 storage where it will remain permanently stored for millions of years. An example of the re-purposing on depleted oil and gas fields for CO2 storage is at Northern Endurance and Acorn CCS Projects in the North Sea which are considering both depleted fields and saline aquifers. Subsurface risk assessments for both these example projects indicate that containment risk is extremely low.
The majority of CCS projects in operation around the world inject CO2 into saline aquifers. These aquifers generally cover very large areas and have associated impermeable top-seals providing the mechanism for permanent storage of large volumes of CO2 over geological time. Trapping mechanism of the injected CO2 include structural, residual, solubility and mineral trapping. The Sleipner project uses saline aquifer storage.
Measuring, monitoring & verification (MMV) to ensure permeance: subsurface modelling of the injected CO2 plume using 4D time-lapse seismic data is a proven method for tracking the movement of CO2 in the subsurface. Using this technique, it is possible, as has been demonstrated at the Sleipner project, to estimate the volume of CO2 in the subsurface and correlate with the injected volumes or baseline, providing real-time MMV of CO2 plume migration patterns and highlight any containment losses.
Myth Buster
Due to several reports in the media of failed CCS projects, many have been led to believe that carbon sequestration is an immature technology that is prone to failure. Recent research provides evidence refuting that supposition. There are currently 43 operational CCS projects around the world of various capacities. When deployed using conventional, proven, and well understood equipment, the sequestration of CO₂ into underground reservoirs is a routine exercise, conducted daily across thousands of hydrocarbon production sites around the world. A recent report investigating the failure of CCS project completion in the United States attributed most failures to the employment of new technology for the capture element rather than the proven and well-defined technology used in performing the sequestration element.
Despite its critics Chevron’s Gorgon CCS project at Barrow Island (offshore Western Australia) is one of the largest carbon sequestration projects in operation, in an annual report dated 30 September 2021, Chevron revealed the Gorgon CCS scheme injected a total of about 2.26 million tonnes of carbon dioxide over the 12 months to 30 June 2021. Continuous monitoring of well conditions via subsurface and surface pressure and temperature gauges during the same period recorded no reported anomalies.
In Norway, the Northern Lights project is an industrial scale CCS project currently under construction by a conglomerate including Equinor, Shell, and Total Energies. The project aims to sequester up to 1.5 million t-CO₂ per year building to 5 million t-CO₂ per year, by injecting carbon, via a pipeline, into a reservoir 2,600 metres under the seabed. Northern Lights will be the first ever cross-border, open-source CO₂ transport and storage infrastructure network offering safe and permanent underground storage to industries from across Europe. Phase one of the project is due for completion by mid-2024. Notably, the rate limiting step for such developments is the construction of a suitable pipeline. This project provides an excellent precedent for Sea-Quester’s business model.
References
- APPEA (2023) Myths vs Facts: Carbon Capture and Storage, Retrieved from: https://www.appea.com.au/wp-content/uploads/2022/08/APPEA_mythsvsfacts_CCS.pdf
- IPCC (2022) Climate Change 2022, Mitigation of Climate Change, Summary for Policymakers
- Fitch P., Battaglia, M. & Lenton, A. (2022) Australia’s Carbon Sequestration Potential – Summary Report, CSIRO
- Boston Consulting Group. (2019) The Business Case for Carbon Capture: Capturing carbon to drive value and fight climate change. Retrieved from https://www.bcg.com/publications/2019/business-case-carbon-capture
- International Energy Agency. (2021) Global Energy Review 2021: CO2 Emissions. Retrieved from https://www.iea.org/reports/global-energy-review-2021/co2-emissions
- McKinsey & Company. (2018, May 2) The world needs to capture, use, and store gigatons of CO2: Where and how?
- International Energy Agency: Annual CO2 capture capacity vs. storage capacity, current and planned, 2020-2030, IEA, Paris https://www.iea.org/data-and-statistics/charts/annual-co2-capture-capacity-vs-storage-capacity-current-and-planned-2020-2030, IEA. Licence: CC BY 4.0
- International Energy Agency: Annual CO2 storage capacity, current and planned vs Net Zero Scenario, 2020-2030, IEA, Paris https://www.iea.org/data-and-statistics/charts/annual-co2-storage-capacity-current-and-planned-vs-net-zero-scenario-2020-2030, IEA. Licence: CC BY 4.0
- Abdulla,A. et al. (2021) Explaining successful and failed investments in U.S. carbon capture and storage using empirical and expert assessments, Environmental Research Letters, Vol. 16, 014036, https://iopscience.iop.org/article/10.1088/1748-9326/abd19e