Ocean Acidification and Carbon Dioxide Capture and Storage

My current project is managing a cross-government team to make recommendations on the required legal and regulatory framework for carbon capture and storage. This is the idea that carbon dioxide (CO2) can be captured at fossil fuel power stations (either pre or post-combustion) and other industrial processes. The gas would then be stored indefinitely rather than being emitted to the atmosphere, where CO2 is the main greenhouse gas. Storage is in underground (usually sub-seabed) rock formations such as exhausted oil and gas wells and in saline aquifers. It is therefore very interesting that OSPAR, the inter-governmental agreement to protect the North-East Atlantic, has just released new reports on the rapid increase in ocean acidification from CO2 in the atmosphere, and on the technical aspects of capturing and storing carbon dioxide in geological structures under the seabed. Made available by the OSPAR Commission as a result of the work of its Offshore Industry and Biodiversity Committees, they are available on www.ospar.org under 'What's New?'. (The site uses frames extensively - see here for the English welcome page et ici for the French one.) The reports will be formally published later in 2006.

The first report 'Ocean Acidification' confirms that high levels of CO2 in the atmosphere are changing ocean carbon chemistry at least 100 times faster than at any time in the last 100 000 years. The pH of seawater (the measure of the balance of acidity and alkalinity) has dropped from 8.2 to 8.1 over the past 200 years. Models forecast that it will drop to 7.8 by 2100, and may drop as low as 7.5 if there is a business-as-usual scenario. This would be lower than anything experienced in the last 10 - 20 million years.

Marine species that rely upon building up calcium-based structures will be adversely affected. These include corals, crustaceans (e.g. lobsters, crabs) and molluscs (e.g. mussels, oysters). Higher levels of CO2 in seawater generally depress the physiological performance of sea creatures, so it cannot be ruled out that the changes will also impact on other marine species.

The second report, 'Placement of CO2 in Subsea Geological Structures' looks at the technical aspects of CO2 capture and storage (CCS) in geological structures under the seabed. It shows that CCS in sub-seabed geological structures is technically feasible, using existing tried and tested technology. The North-East Atlantic offers significant potential for CCS: it could take most of the European Union's CO2 emissions from major point sources for several centuries. With well selected, designed and managed sites, retention of CO2 for several thousand years (or even longer) could be achieved. Evaluation of any proposed sites needs to take account of the risks to the marine environment as well as the benefits in mitigating climate change and acidification of the oceans. Monitoring will be important and the report describes how seismic and gravimetric techniques can be used.

The report concludes that guidelines or a framework for risk management for the storage of CO2 are needed. OSPAR is putting work in hand to produce these. (Taken from the OSPAR press releases.)