CO2 capture and storage in the sea bed.
A critical perspective and questions for
discussion
EU Maritime Days Gijon May 2010
Peter M. Haugan, Geophysical Institute,
University of Bergen
www.gfi.uib.no
Some provocative statements
1. There are no measurement techniques which could prove
that stored CO2 stays in place with sufficient accuracy for
verification.
2. There is a real danger of leakage during the storage
operation.
3. Subseabed storage sites have small capacity and are
expensive to develop and monitor.
4. Obtaining storage permits will take a long time.
If this is right, then CCS will not be a bridge from fossil fuel to
renewable energy.
www.gfi.uib.no
Utsira with Tordis and Sleipner
Tordis
Tordis
Sleipner
Sleipner
Pedersen, UiB
Norway ongoing: Injecting 1 Mt CO2/y from natural gas production
at Sleipner into Utsira formation in the North Sea since 1996
Vertical and horizontal seismic sections at Sleipner-Utsira
sand
Central chimney conduit plus rapid leakage through 1-5 m shale layers
Vertical movement of CO2 from Sleipner in Utsira
Comparing observed (seismic sections) development of thickness
versus radius in 9 distinct layers with analytical gravity current
dynamics in porous and permeable media.
Layers have started filling gradually. Leaks occur through thin mudstones.
Model-data consistency requires either CO2 permeabilities order of magnitude
lower than measured on core samples or CO2 layer thickness from seismic are
overestimated –> Possible that CO2 saturation is small and CO2 has escaped.
Bickle et al 2007 Modelling carbon dioxide accumulation at Sleipner: Implications for
underground carbon storage. Earth and Planetary Science Letters 255, 164-176.
Depth of Utsira is close to CO2 low density regime
+ high sensitivity to
temperature
=>Hard to estimate
CO2 in place
Other parts of Utsira
are quite clearly in
CO2 low density
regime and should
be avoided;
previous capacities
over-estimated.
Still Utsira is probably
the most suitable
formation in the
North Sea with high
permeability and
porosity.
Outreach material: No significant leakage
Truth: Large uncertainty on volumes, fluxes
Injection of polluted water from Tordis field into/beneath
Utsira 2008: induced fracture and leakage
Later studies (2010) have shown many similar occurrences.
Length:
30-40 m
Depth:
7m
Possible leakage monitoring
Above: Shallow seismic (sparker) profile across
the Gullfaks field. Courtesy of M. Hovland, Statoil
Below: Acoustic detection. CO2 release experiment
conducted by Brewer et al. (GRL, 2006). Courtesy
of P.G. Brewer, MBARI
Above: Model from high resolution multibeam echo
sounder. (Vertical axis exaggerated five times).
Haltenbanken pipeline down to the right. Courtesy of
M. Hovland, Statoil
Below: Collection structure for shallow gas (CH4)
monitoring at Troll. Courtesy of NGI and IFE
Norwegian Climit-project 2007/2008 ”Subsea Storage of CO2; the marine component”
(Alendal et al) literature survey http://www.cmu.uib.no/projects/CO2Marine
North Sea model study of leakage (Blackford et al, MPB 2008)
using well tested hydrodynamic model with tides:
Small impact relative to that of uptake scenarios
Model details:
Leakage 5 times
Sleipner injection
7x7 km grid
Dissolved CO2
Highly local effects
not resolved
Blackford, Jones,
Proctor and Holt.
MPB56 (2008),
1461-1468.
Modelling from Kendall, PML, building on Blackford et al (MPB 2008)
When eagerness dominates and scientific
basis is not solid
Wishful thinking for long term
evolution of fluid – rock
interaction?
Figure included in IPCC
SRES 2006.
Studies of natural CO2
reservoirs now question
these long term effects.
From IPCC SRES CCS, 2006
Will carbon sequestration be
significant for 21st century CO2 levels?
Present projects are only order 0.01 Gt C/year, but are
increasing, so maybe useful in the intermediate to long
term (not short term!)
OR
the projects may turn out to be environmentally
unacceptable, unreliable or too slow to provide a bridge,
in which case the net effect is probably higher emissions
because of false beliefs.
Will carbon sequestration be
significant for ocean acidification?
Some local effects from leakage – studies are needed.
Most important effect via the resulting net emissions to the
atmosphere.
Some provocative statements
1. There are no measurement techniques which could prove
that stored CO2 stays in place with sufficient accuracy for
verification.
2. There is a real danger of leakage during the storage
operation.
3. Subseabed storage sites have small capacity and are
expensive to develop and monitor.
4. Obtaining storage permits will take a long time.
If this is right, then CCS will not be a bridge from fossil fuel to
renewable energy.
www.gfi.uib.no
How to assess the mitigation of global warming by carbon
capture and ocean/geological storage
Peter M. Haugan and Fortunat Joos
Motivation:
• What may be gained from CCS and how do we quantify the
benefits of leaky reservoirs/temporary storage?
Approach:
• Generic climate model study
• Choose reference scenario and sequestration cases
• Generate results and compare different metrics
Peter M. Haugan and Fortunat Joos 2004. Metrics to assess the mitigation of global warming by carbon
capture and storage in the ocean and in geological reservoirs. Geophysical Research Letters 31, L18202,
doi:10.1029/2004GL020295.
Approach
• Use reduced form carbon cycle climate model in millennium time scale runs:
HIgh Latitude Diffusion-Advection (HILDA) ocean model coupled to a 4-box
biosphere model and an energy balance model
• Choose stabilization reference scenarios: WRE 550, 450 and 1000
• Capture and store 30 % of emissions after a ramp-up period 2010-2035 =>
CCS comes in addition to stabilization, not instead.
• Investigate effects of
–
–
–
–
–
Perfect storage PS (no leakage)
Geological storage with 0.01 annual leakage
Geological storage with 0.001 annual leakage
Storage in the ocean at 800m (dissolved)
Storage in the ocean at 3000m (dissolved)
• Include energy penalty of 20% and 5%
Deduce emissions corresponding to the reference
(stabilization) scenarios with no carbon storage
Anthropogenic carbon
emissions for the
WRE450, WRE550,
and WRE1000
stabilization scenarios.
Use model to investigate effects of capture and storage of 30
% of these emissions
Output parameters to look at for storage cases (S):
– Atmospheric CO2
– Surface air temperature T
– Rate of change of surface air temperature
– Global Warming Avoided (GWA):
t
 (T
t
GWA(t) =
 (T
ref
 Ts )dt
GWANorm(t) =
t0
 Ts ) dt
ref
 T0 ) dt
t0
t
 (T
t0
Storage effectiveness EFF(t)=GWA(t) / GWAPS(t)
ref
(a) atmospheric CO2, (b) global average surface temperature change, (c) rate of global
average surface temperature change, and GWA (d) in °C year, (e) in percent of the
cumulative warming of the reference case, and (f) relative to the perfect storage case for
WRE550.
Impact of geological vs. ocean storage on climate
Maximum rates of change of temperature are not much affected by any of
these carbon storage cases, not even the perfect.
Geological storage with 0.01 annual leakage fraction is less effective than
shallow ocean storage (800m). Its effectiveness1 for storing 30% of
emissions peaks at 15 % and GWA gets negative after 6-700 years.
Geological storage with 0.001 annual leakage fraction has similar
performance to deep ocean storage.2
Normalized GWAs for a given storage case tend to collapse to similar values
for different reference scenarios.
Reducing energy penalty from 20 to 5 % has limited effect.
1Storage
effectiveness EFF(t) is defined here to be the fraction of the GWA obtained
relative to that obtained by perfect storage.
2Deep ocean storage in lakes on the seafloor would perform better than directly
dissolved because of delayed mixing into the water column.
Density of liquid CO2, seawater, CO2-enriched seawater and CO2 hydrate
Gas
Buoyant
liquid
Negatively
buoyant
liquid
Ocean issues related to CCS
-> dissolution, spreading, acidification and potential
biological damage, communication to atmosphere.
In addition to the options studied so far there are some yet
unexplored versions:
- Inject into high salinity brine water in deep depressions,
e.g. the Red Sea, or
- Inject into anoxic basins, e.g. the Black Sea.
- Inject in deep sea sediments in the negative buoyancy
zone where dense phase CO2 is denser than formation
water and hydrates are stable (House et al., 2006)
+ Perhaps others will be found?
An option that may be better but is
presently banned (1.2.3&4 in EU directive)
Only the deep ocean (> 3000m) provides cold
temperatures and high pressure to make
CO2 negatively buoyant.
Favorable hydrate formation; possibly injection
into deep sea sediments.
If geological storage falls out of favor for cost or
environmental reasons, perhaps deep
ocean will come back ?
House et al., 2006