Presentation given by Professor Michael Steven from University of Nottingham on "Potential environmental impacts of CO2 leakage: results from the ASGARD facility" in the Storage Technical Session on Monitoring & Verification at the UKCCSRC Biannual Meeting - CCS in the Bigger Picture - held in Cambridge on 2-3 April 2014

1. Potential environmental impacts of
CO2 leakage:
results from the ASGARD facility
Michael Steven and Karon Smith
University of Nottingham

2. Could CO2 leak back to the surface?
• Leakage is generally unlikely, but...
– Fractures or faults in the cap rock.
– Poorly designed wells
or badly sealed abandoned wells.
– Pipe rupture during transport to storage sites.
Research Justification
Murphy’s Law
If anything can go wrong, it will.

3. CCS: regulatory issues
• Any regulatory framework will require:
– environmental impact assessment
... to understand the risks
– early warning systems for leakage
... to manage the risks
... to provide an accounting system
• And to help build public confidence

4. ASGARD
Artificial Soil Gassing And Response Detection
The ASGARD Project
How does leaked CO2 affect terrestrial
ecosystems?
Stress responses in plants
Stress detection and monitoring

5. CO2 injection
to 60 cm
Access tube for
monitoring
Lab
Gas supply

6. 2
0
1
0

7. Gas control system
Mass flow
controllers
Pipes to field
Computer interface
CO2 delivered at
1 l/min per plot

8. Gas delivery and measurement

9. CO2 Distribution across the grass plots
2006 data

10. N

11. Plant stress: visual symptoms
7-14 days after start of gassing
oilseed rape
K Smith 2010
barley
beetroot

12. Spectral indices
Maize, S. Yahaya 2009

13. Different stresses – different symptoms?
CO2 stress CO2 control
Herbicide stress Herbicide control
Maize, S Yahaya 2009

14. Remote sensing conclusions
• Plant stress responses due to CO2 are
detectable by a variety of spectral indices
– From about 10% CO2 in soil
• Remote sensing indices can detect stress at
sub-visual levels
• Spectral responses to CO2 stress are similar to
responses to herbicide, although the
physiological effects differ.

15. Environmental impacts of leaks
• CO2 effects on plant growth and development?
• Are some plants more sensitive to CO2?
– Is competition between species affected?
• Are effects due directly to CO2 or lack of O2?

16. Bean germination
M Al-Traboulsi 2008

17. CO2 effects on bean emergence
LD50
M Al-Traboulsi 2008

18. Access tube for
root camera,
down to 60 cm
Primary root
Secondary roots

19. Oilseed rape : Number of Primary and
Secondary Roots
Top: Pre-gassing. Bottom: After 41 days gassing Primary roots
Secondary Roots
Control High Gas Low Gas

20. Plant competition
• Grass and clover mix was sown in 2010 and left to
establish overwinter. CO2 was injected from 21/3/11.
• CO2 had a greater effect on clover than on grass
Grass/clover plots taken on 26th July 2011
Gassed Control

21. Plant stress response conclusions
• Severe responses to CO2 occur in all plant species
• The primary effects seem to occur at root level
• Some species are more sensitive, affecting
competition
• Our experimental system does not allow direct
CO2 effects to be discriminated from the indirect
effects of O2 depletion, but the responses are
often greater than expected from O2 depletion
alone.

22. CO2 flood scenario
• Catastrophic pipeline rupture
• Stable atmospheric conditions at night
• Topography that confines the gas

23. J Lake, 2010
3 species selected for
follow-up analysis
Treatments:
CO2
N2
Chamber-only
Open

24. CO2 flood conclusions
• Biochemical analysis allows very sensitive
testing of response mechanisms
• Although non-significant, the suggested effects
were somewhat larger than expected
• The lack of a positive response is good news
for CCS: it indicates that long term effects on
the environment are minor.

25. Advantages of the Asgard approach
• Combines –
– The realism of field study with
– A high degree of experimental control
– Replicated results
• The ability to generalise
• The ability to test innovative techniques

26. What next?
Can remote sensing detect vegetation stress responses?
− and distinguish from false anomalies?

27. Remote Sensing for early warning
Previous work:
8 out of 9 known
gas leaks (methane)
were detectable
using IKONOS.
But a pipeline
provides context.
Leakage from CCS
could be 2-D.

28. Acknowledgements
• Jeremy Colls
• Karon Smith
• Ravi Patil
• Manal Al-Traboulsi
• Sani Yahaya
• Jiang Jinbao
• Yang Wei
• Janice Lake
• Barry Lomax
• British Geological Survey