The University of Nottingham Karon L Smith Michael D Steven Jeremy J Colls.
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Transcript of The University of Nottingham Karon L Smith Michael D Steven Jeremy J Colls.
The University of Nottingham
Karon L SmithMichael D StevenJeremy J Colls
The University of Nottingham
ASGARD (Artificial soil gassing and response detection)
–background
• An understanding is required of the risk of leakage from the storage sites or from the infrastructure used to transport the CO2
• Detection of leaks and knowledge of the effect of leaking CO2 on surface ecosystems is important.
• Our approach is to inject controlled amounts of CO2 into soil – Test detection techniques using remote sensing or
isotope analysis– Monitor changes in plant and soil conditions– Test sensitivity to soil and plant types and gassing rate
The University of Nottingham
ASGARD –development of experimental site
•The site was set up at the University of Nottingham’s Sutton Bonington campus•34 plots each 2.5 x 2.5 m were marked out and prepared with 3 crops.
– 8 were left as pasture– 8 plots were planted with
barley– 8 plots were planted with
linseed– 6 plots were left for additional
experiments– 4 plots were marked out at a
distance from the main site to act as remote controls
The University of Nottingham
ASGARD –development of experimental site
•CO2 gas was delivered at a depth of 60 cm to 4 plots in each crop from 200 l cryotanks via MDPE pipes•Gas delivery was controlled with solenoid operated mass flow controllers•Gas was delivered at a rate of 3 l hr-1 between 16th May and 26th September 2006
The University of Nottingham
Gas concentration
Soil gas concentration was measured on a daily basis using permanently installed sampling tubes.
Correlation between O2 and CO2 concentrations in grass
y = -0.2147x + 20.078
R2 = 0.9662
0
5
10
15
20
25
0 20 40 60 80 100
CO2
O2
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
13/05/2006 07/06/2006 02/07/2006 27/07/2006 21/08/2006 15/09/2006Date
CO
2 co
nce
ntr
atio
n (
%)
Grass
Linseed
Barley
Control
Remote control
The University of Nottingham
Gas distribution within plots
Barholes, 30 cm deep, were made at 50 cm intervals over the plot. CO2 measurements were taken using the GA2000 gas detector
The University of Nottingham
Surface CO2 measurements
Draegar tubes were used to measure CO2 at the surface
0 50 100 150 200 2500
50
100
150
200
250
The University of Nottingham
CO2 flux measurements
CO2 flux was measured by BGS using a West systems fluxmeter
R2 = 0.8457
0
2
4
6
8
10
12
14
16
18
20
0.0 10.0 20.0 30.0 40.0
conc %fl
ux
pp
m/s
Correlation of CO2 flux with soil CO2 concentration
The University of Nottingham
Vegetation stress
Spectral measurements were taken at 50 cm intervals along a transect in each plot.
Temporal change in ratio Grass 725:702 nm
0.0
0.5
1.0
1.5
2.0
2.5
03/05/2006 23/05/2006 12/06/2006 02/07/2006 22/07/2006 11/08/2006 31/08/2006 20/09/2006 10/10/2006Date
Rat
io
Gassed
Control
Remote control
The University of Nottingham
Isotope measurements
Isotope ratios as a function of CO2 concentration
-35
-33
-31
-29
-27
-25
-23
-21
0% 20% 40% 60% 80% 100%CO2--
d1
3
Grass 01 Aug 06
Linseed 27 Jul 06grass model
linseed modelremote grass 04 Aug 06
The University of Nottingham
Effect of CO2 flow-rate
Four flow-rates were tested.3, 2, 1 and 0.5 l min-1
In future experiments a flow rate of 2 l min-1 will be used to maximise spread of CO2 throughout the soil whilst minimising costs.
Affect of flow rate on gas concentration 15 cm from source point
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
G1 15 G2 15 G5 15 G7 15
CO
2 co
nc
% 3.0
2.0
1.0
0.5
Affect of flow rate on gas concentration 70 cm from source point
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
G1 70 G2 70 G5 70 G7 70
CO
2 co
nce
ntr
atio
n %
3.0
2.0
1.0
0.5
The University of Nottingham
Conclusions
We have successfully developed the ASGARD facility and demonstrated:
• Controlled release of CO2 into the soil• Demonstration of CO2 movement within, and flux out of the
plots • Detection of plant stress effects through spectral monitoring
and the ability to identify leaking CO2 at low soil concentrations
• Successful use of isotopes in discriminating between geological and biogenic carbon for identification of leaking CO2
• We believe that characterisation of leaking CO2 hazards in the environment and validation of detection techniques will help to provide the basis for public confidence in CCS.
The University of Nottingham
Acknowledgments
We would like to thank UKCCSC and SRIF3 for funding this project
We also thank Darren Hepworth, Maria Ortega and Marta Ortega for their help during the field season.
