Effects of Vertical DIC
Distribution on Storage
Efficiencies of Direct Injection of
CO2 into the Ocean
Baixin Chen, M. Nishio, and M. Akai
National Institute of Advanced Industrial Science and Technology
(AIST), 1-2-1 Namiki, Tsukuba East, Tsukuba 305-8564, Japan
1
Why ocean sequestration?
Large capacity (IPCC Srpt. on CCS 05) :

“Roughly 2,300 to 10,700 GtCO2 would be added
to the ocean (above the natural pre-industrial
background) in equilibrium with atmospheric CO2
stabilization concentrations ranging from 350 ppm
to 1000 ppm, regardless of whether the CO2 is
initially released to the ocean or the atmosphere.”
Actually, it is an artificially acceleration of
natural oceanic uptaking of CO2 across
air/sea interface.

Over the past 200 years the oceans have taken up
500 GtCO2 from the atmosphere out of 1300
GtCO2 total anthropogenic emissions. .
2
Questions:
Assessments on CO2 Ocean Sequestrations
How long the CO2 injected
could be kept in the ocean ?
(efficiency)
Is it safe for marine organisms
and animals? (bio-impacts in
near and far fields)
The long-term impacts on
global ecosystem ( ? )
3
How to perform
(IPCC Srpt. on CCS, 2005)
4
Injection of CO2 by moving-ships
5
CO2 Injection Nozzle & Droplet Size
Distribution (Minamiura et al., GHGT-7, 2004)
Nozzle and CO2 drops from Lab. Exp.

Drop deformation

Hydrate layer formed at the
interface
6
How long the CO2 injected could be
kept in the ocean ?
Efficiency or retention :


OGCMs (depth, locations)

Caldeira et al. (GRL, JGR , 02)

Orr et al. (Climate Change 02 and GHGT-5-00 )

…..
Box models (depth, bio-chemical systems)

Herzog et al. (Climatic Change, 2003)

Sohma et al, (JGR, 20050)

….
In this study :
If the injection parameters play the role
on storage efficacy?
7
How to handle the injection parameters ?
1. Plume dynamics (coupling the injection
parameters and currents) in short-term
2. For long-term efficiency,
By OGCMs for long-term

Using fine resolution:

10th meters vertically
(Very difficult if not impossible currently)

Nesting grids systems

Good and will be trying
By Box models

OK (How about the horizontal transportation
roles?)
In this study :
Implemented the initial vertical distribution of
DIC from (1) to the existed data from (2).
8
Effect of injection parameters
on storage efficiency:
1
C (t )   C 0 (h, t )  P[ x(h)]dx
0
C (t )
: the storage efficiency with an initial vertical
distribution (pdf)
C 0 (h, t ) : the storage efficiency without initial vertical
distributions (OGCM data).
h : the depth of the ocean (m)
t : time (year)
P[x(h)] : the mass pdf of DIC initial vertical distributionas
a normalized depth (x (h)).
9
Long-term storage
efficiency data
interpolated from
OGCMs
10
The data can be interpolated
numerically (Caldeira et al. GRL 2002)
Injection site: Tokyo
Injection site: Tokyo
T > 100 years
T = 120 - 500 yrs
T < 100 years
T = 20 - 100 yrs
11
Initial Vertical
Distributions of DIC
produced by
coupling injection
parameters with
ocean current from
two-phase models
12
Near-field Two-phase Model
Ocean surface
Towing pipe
Initial DIC
distribution
Turbulent diffusion
X3
CO2 droplet Dynamics
and biological impacts
Injection ports
installed nozzles
X1
Can go to the bottom
13
Evolution of DIC Plumes
T=1.0 min
1.34
1.26
1.17
0.89
0.65
0.00
(Chen et al., JGR, 05)
T=23 min
T=70 min
Outline of CO2 Droplet Plume
CO2 Rich-water Plume
Injection rate : 100 kg/sec
Initial drop size: 15 mm
Injection depth : 2000 m
Injection port : Horizontal
14
X=10 m
X=180 m
X=10 m
X=10 m
Vertical distributions of DIC
Injection site: Tokyo at Depth of 2000 m
15
Effect of initial DIC
vertical distribution
on efficiency
16
CO2 Injection Parameters
Injection type: Moving-ship
Injection rate: 100kg/sec by moving-ship
(0.1 Ggt C /year)
Droplet sizes: 5, 10, 15, 20, 30, 40 mm
Injection depth: 1000, 1500, 2000, 2500 m
Injection site: Near Tokyo (T, S and current
data )
17
Effects of initial droplet
size on efficiency
Injection site: Tokyo
18
Effects of injection
parameters on efficiencies
Injection site: Tokyo
Time : 500 yrs
S  1.0  c co
19
Efficiency and (Sensitivity)
Injection depth H
(m)
By 8 OGCMs
(Orr et al. GHGT-5)
By 8 sites (MOM)
(Tokyo, New York,
Bombay …, By Caldeira
et al. GRL 2002)
By droplet sizes
(D0 = 5 – 40 mm)
800
1500
15 – 37
(+0.42)
26 – 57
(+0.35)
50 – 82
(+0.25)
15 – 30
(+0.33)
40 – 57
(+0.17)
70 – 89
(+0.10)
20 – 25
(0.21)*
38 – 47
(0.20)
* : H = 1000 m and D0 = 5 – 10 mm;
2000
50 – 60
(0.11)
3000
62 – 72
(0.10)**
** : H = 2500 m
20
Conclusions & discussions
Within 500 years after releasing CO2 at rate of 0.1 Ggt C
/year by moving-ship:
 Efficiency is related with not only depths and sits but
also drop size injected.
 For droplets size D0 = 5 – 40 mm, the storage
efficiencies could be reduced by range of 5% to
20% if release depth less than 2600m due to the
rising plumes.
 Implement of DIC vertical pdf into OGCM for further
checking. (Nesting grids system ?)
 The roles of injection parameters on biological
impacts in near-field should is another challenge.
21
Thank you !
22
In this study:
Assessments on CO2 Ocean Sequestrations
How long it could be kept in the ocean ?
(efficiency)

OGCMs (depth, locations) (Caldeira et al. in GRL, JGR 02;
Orr et al. in Climate Change 02 and GHGT-5-00;

…..)
Box models (depth, bio-chemical systems) (Sohma et al, JGR-05,
….)
How about the injection parameters?
Is it safe for marine bio-masses? (bio-impacts)

Lab. Exps. (Acute injury of fishes, Mortality and Injury of
zooplankton by Portner; Shirayama; Ishimatsu; JO and IPCC
SRPT. on CCS) for Near-field and short-terms.

Long-term impacts on bio-eco system ( ? )
Do the Injection parameters play the role ?
The impacts on global ecosystem ( ? )
23
Methodologies:
Implement the near-filed two-phase box model to the
OGCM by:
 Provide the initial vertical distributions of DIC from
near-filed model
 Use data of long-term storage efficiency from
OGCMs and Box models to estimate the effects of
initial-vertical DIC distribution.
because the time scales :
dtOGCM (2 ~ 3 hrs) > Tdiss (1~ 1.5 hrs)
 We checked the injection depths and D0s for two
injection types (horizontal and vertical injection
ports) at a fixed injection rate (100kg/sec).
24
Model validation
(vs field Exp data by P. Brewer et al. 2002)
1.00
Modeling Prediction (Droplet A)
Droplet Diameter (cm)
Modeling Prediction (Droplet B)
0.80
0.60
0.40
0.20
:Observation Data of Droplet A
(P. Brewer et al)
:Observation Data of Droplet B
(P. Brewer et al)
0.00
10
25
40
55
70
Elapsed Time (min)
25
Ascending /Descending of CO2
droplet in the ocean
Ascending /descending Distances (m)
800
Release depth: 1000m
Release depth: 2000m
600
Release depth: 2895m
400
200
0
-200
-400
Release depth: 2900m
-600
Release depth: 3000m
-800
0
3
6
9
12
15
18
21
24
Initial Diameter of CO2 Droplet (mm)
26
Model of an Individual CO2 Droplet
(dissolution and movement)
c
d ln( mc )
dur  s
3ur 2
 (( 1.0  )g 
Cd )  ur
dt c
s
4D
dt
dD
1 D dc 2 ShD f Cs
 (

)
dt
c 3 dt
D
Key Parameters:
•Sh : Sherwood number
•Cs: The solubility
•α : The effective area coefficient
•Cd: Drag coefficient
27
Sub-models of drag
coefficient (Lab. data from Dr. Ozaki)
4.5
Drag Coefficient Cdr and Cdd
4.0
Terminal velocity of CO2 droplet
(cm s-1)
20
: Cdr Rigid spheres Eq. (2)
: Cdd Rigid spheres with
deformation Eq.(1)
3.5
3.0
O: P=10.1MPa;T=275K
O: P=15.1MPa;T=278K
O: P=20.1MPa;T=278K
Exp data (Ozaki et al)
2.5
2.0
1.0
0.5
Exp Data (Ozaki et al)
10
: Cdr Rigid spheres Eq. (2)
0
0
:Cdd Rigid spheres with deformation Eq.(1)
5
10
15
20
25
CO2 Droplets Diameter (mm)
1.0
1.5
2.0
2.5
3.0
Logarithmic Reynolds Number
Re 
15
Re 
5
1.5
0.0
O: P=10.1MPa;T=275K
O: P=15.1MPa;T=278K
O: P=20.1MPa;T=278K
Du r
w
ur =|ud – uw|
The relative velocity
3.5
Cdd  Cdr( Aeff / Aeq )Cd
Cdr  24( 1  0.125 Re 0.72 ) / Re
(1)
(2)
( Aeff / Aeq )Cd  1.0  ( 5.6419  8.3484  10 3 Re
 1.4596  10 6 Re 2 )  10 4 Re
28
Near-filed Bio-impacts for two CO2
release types
Elapsed time: 180 min
Vertical release type
Horizontal release type
29