Energy - Allianz Global Corporate & Specialty

Technology options for CO2 Removal
Post-combustion
Pre-combustion
Oxy-fuel
Coal
Gas
Biomass
Gasification
Gas, Oil
Coal
Gas
Biomass
Coal
Gas
Biomass
32 Special Topic – Energy
Air
Air
Air/O2
Steam
Reformer
+ CO2 Sep
Power & Heat
O2 Separation
Power & Heat
This is a highly efficient solution with low heat of reaction,
easy and low temperature regeneration and tolerance
to oxygen and contaminations in gas. However,
there is a risk of toxic release of ammonia and buyers
need to be found for the ammonia sulphate that is a byproduct
of the process. Again corrosion is possible and
H2
Air
CO2
Power & Heat
N2
N2
O2
CO2
Separation
N2
O2
CO2
Compression &
Dehydration
Source: Bellona
Different routes, one destination – the methods of pre-combustion, post-combustion and oxy-fuel CO ² separation each require more additional energy
to existing power & heat plants, whereby oxy-fuel separation is the most energy-efficient. A further concern for all three is potential long-term risk for
the storage itself including storage in cavern. This area is still under a lot of investigation.
therefore adequate materials are necessary. The main
incident up to now is clogging.
Finally, a new kind of post-combustion CCS is the antisublimation
process. In this case, flue gas is cooled and
conditioned to be dried and then CO2 is frosted and
liquefied. No chemicals are involved, but efficiency
seems to be low. Up to now, they have not been tested at
a pilot plant and are still under investigation at laboratory
level.
The pre-combustion processes are based on an integrated
gasification combined cycle with steam reformer,
partial oxidation and a shift reactor to convert carbon
monoxide to CO2. This is followed by the capture of CO2
(as in post-combustion unit) and use of hydrogen and
nitrogen in a gas turbine. The process needs oxygen
coming from an air separation unit. This is the shortest
term for market and the easiest to realize. Up to 90 to 95
percent of the CO2 could be captured.
Oxyfuel-combustion processes were designed based on
technologies used for the treatment of ethylene and in
boilers in combination with proven technologies given
by referenced companies in order to supply a global process
management to their clients. It is a combined process for
power plants using fuel or coal where the end gas processing
unit can catch and release CO2. Using this method, 100
percent of the CO2 could be captured. However, the efficiency
of power plants would be lowered to below 70 percent,
while costs rise by about 30 percent. Oxygen content needs
to be controlled to below 25 percent. Supercritical CO2 is
used in some processes to allow pumping of CO2 and requires
some special equipment. Material selection is essential
and experiments have been done to select them. Cold
boxes for the cryogenic recovery of CO2 and condensers require
the use of aluminium and dedicated processes of
welding. Temperature control is needed to prevent hydrate
and dry ice formation.
With benefits come costs
Capturing and compressing CO2 requires a great deal of
energy and would increase the fuel needs of a coal-fired
plant with CCS by 25 to 40 percent. These and other system
costs are estimated to increase the expenses of energy from
a new power plant with CCS by 21 to 91 percent. Therefore,
cost-effective carbon sequestration schemes could be
identified as a key need for dealing with the impact of CO2 on
global climate change.
The main challenge of CO2 capture and storage is the high
cost of technologies using the current state-of-the-art
technologies. Separation and compression of CO2 account
for the bulk of these costs, while the costs of transportation
and injection are comparatively lower. Another issue could
be the energy and CO2 release used to capture CO2 versus the
efficiency of the capture process. All of the research and development
studies related to CO2 capture and storage are of
significant interest for these objectives.
As a result, Allianz works closely with its customers develop -
ing such processes. It offers them insurance warranties for
running pilot phases and pre-industrial phases as well. This
support means understanding the technologies they are
developing and what the main technical concerns are in
order to create more appropriate insurance solutions based
on the exposures they could face.
JEAN INGLESE
Allianz Risk Consulting, France
jean.inglese@allianz.com
HTTP://CDIAC.ORNL.GOV/
WWW.BELLONA.ORG
WWW.WWF.ORG
Guest commentary
from Matthias Kopp from World Wildlife
Fund/Climate Programme
When considering CCS there are two main
aspects to balance very carefully – the risks
involved in storing CO2 underground and
the benefits to our climate from avoding
these emissions to the atmosphere. It is becoming
increasingly urgent for emissions to
reach a global peak, then decline and ultimately
be reduced to levels where climate
scientist request them to, some 80 percent
or more (compared to 1990) over the next 40 years globally. Therefore,
further to or where renewable or less risky alternatives do not
exist or are not available, every technology with an acceptable risk
profile that delivers mitigated emissions needs to be considered.
CCS in fossil-fired power plants does not generally meet this requirement.
Various studies demonstrate that CCS in new-built fossil-fired
power stations for instance for Germany is even counterproductive
in the move to a carbon-free power sector, while it might be
needed as a retrofit option some time in the future if structural
emission reductions are not delivered quickly enough.
It appears to be a different story in emerging economies like China
where emissions will realistically only be controlled if also new
power plants can be equipped with CCS technology. But with our
current level of knowledge, we need to rigorously test CCS applications
for those industrial processes where emissions directly from
the process cannot be avoided. Germany, for example, will be stuck
with annual emissions in the order of 40-60 million tons of CO2 in
2050 from steel, cement and chemical processes, and for the time
being no other options can be identified besides storing the emissions
those industries generate underground, if we want to ensure
industrial production and jobs from those industries. Limitations to
suitable potential storage space also strongly point towards using
available reservoirs strategically and wisely – in Germany, hence, for
industrial emissions.
Regardless of whether CCS is used in power plants or industrial facilities,
any possible risk to humans, groundwater or ecosystems from
stored CO2 needs to be rigorously tested to the maximum. Such effects
and dangers will have to be avoided. The technologies developed
to reliably monitor that stored CO2 stays underground also
need to be very robust. If this is not ensured, we would still continue
to use the atmosphere as our carbon dump. There is a critical role
for the private sector, policy makers, insurers and society as a
whole to create the conditions in which mutual trust and legal frameworks
are established based on solid research and testing so that
vital technologies can be applied to help maintain the planned
emissions reduction targets without obstructing our progress towards
decarbonized economies.
Special Topic – Energy 33