Success for world-first experiment to study the effects of a
leak from CCS storage site
28th June 2012
The critical stage of a world-first experiment, to monitor
what might happen if CO2 leaks from an underground
storage reservoir, has been successful. Following a complex
drilling operation, the injection of CO2 from a
shore-based laboratory into shallow marine sediments is allowing
scientists to determine whether (and how) such a leak from a CCS
sub seabed storage site would adversely affect marine life. The
experiment is also enabling the assessment of various ways of
monitoring for CO2 leakage.
As the world searches for viable
climate change mitigation strategies, the approach of Carbon
Capture and Storage (CCS) is one such method that is
attracting
significant international attention and is emerging as one of the
frontrunners for tackling climate change. CCS is the process by
which CO2 is
captured, from power plants and industrial actions, before it is
emitted into the atmosphere and then pumped into deep sub-seabed
reservoirs / geological structures for permanent storing. The risk
of leakage from storage sites is thought to be low, however, it is
vitally important to thoroughly investigate the benefits and risks
of potential mitigation strategies early in their development.
One such research project is the
Quantifying and Monitoring
Potential Ecosystem Impacts of Geological Carbon Storage
(QICS), funded by RCUK / NERC and led by Plymouth
Marine Laboratory in collaboration with the Scottish Association
for Marine Science and four other institutions. The project’s
primary experiment is a world-first and has been releasing moderate
levels of CO2 into shallow sediments in a Scottish Bay,
enabling scientists to study the progress and effects of a
controlled CO2 leak and extrapolate these to real-life
situations, which might occur in the future.
For the last 30 days
CO2 has been supplied from a “pop-up” lab and travelled
through a borehole under the sediment to the release site, 350
metres from the shore and 12 meters below the seabed of
Ardmucknish Bay near Oban. Initial results have shown that
the first two phases of the project (construction and
CO2 release) have been successful and that the
CO2 “behaved” as expected. Localised impacts had been
anticipated and divers visiting the site have observed that some
creatures are affected while others remain unaffected.
The QICS project leader, Jerry
Blackford from Plymouth Marine Laboratory, said: “The experiment is
going exactly to plan and we are very pleased so far. We are now at
the stage of collecting detailed data which will enable us to get
closer to predicting what might happen if a real leak occurred on
an active storage site. As well as looking for environmental
impacts the experiment has allowed us to test a range of monitoring
equipment in a real world setting”
The coordinator for this
experiment, Dr Henrik Stahl from the Scottish Association for
Marine Science, commented: “CO2 gas has been bubbling
out of the sediments over the last few weeks and we have seen a
clear but localised drop in the pH in the sediments and overlying
water in the bubble zone, as expected. This drop is due to the
CO2 reacting with the seawater, which alters the
chemistry of the surrounding water and sediments and reduces the
pH. Some animals, such as sea-urchins living in the sediments, seem
to react negatively to the increase in CO2 whereas
others, such as crabs, seem to be attracted or unaffected by the
bubbles; so there could be both winners and losers in a real-life
situation. The next step is to turn off the gas flow and continue
to study the recovery of the affected area.”
“Even though only a very small
area of seabed is being temporarily affected by this experiment, we
are confident that it will provide valuable information to help
understand the implications of CO2 for marine life,
should a leak occur elsewhere.”
Although the gas injection has
now been turned off, the site will continue to be monitored until
at least September and scientists are confident that ongoing
monitoring and analysis will prove essential in furthering the
understanding of how leaked CO2 will move through
sediment and how ecosystems will respond.