Hydrocarbon Processing - January 2022 - 42

Carbon Capture/
CO2
Mitigation
G. C. SHAH, Consultant, Houston, Texas
Tips to avoid pitfalls in CO2
In recent years, growing concern
) levels has put mounting
capture projects. However, an array
capture projects
about increasing atmospheric carbon
dioxide (CO2
pressure on governments and on processing
industries to curb carbon emissions.
Consequently, this has accelerated
CO2
of challenges that could, if not addressed
adequately, hamper these otherwise
well-intentioned projects. This article
examines the pitfalls that a risk manager
should consider to eliminate or minimize
risks to ensure safety, environmental
sustainability and economic success.
CO2
mitigation/elimination technologies
adoption. Many companies/
organizations in the global hydrocarbon
processing industry are investing in new
technologies and processes to mitigate
or eliminate CO2
emissions. However,
differences among science communities
and industry exist in how quickly
this transition should take place. Atmospheric
experts stress the need for rapid
transition, while industry professionals
urge a calibrated and gradual approach.
On a national level, a rapid transition
to less-familiar technologies or nascent
low-carbon or zero-carbon technologies
could cause massive economic and
societal disruptions. Some experts maintain
that lofty phrases such as " carbon
capture, "
" zero-carbon economy " and
" carbon-free world " tend to fuel hype
while presenting a consequent lack of
adequate thought to the risks associated
with these relatively less-familiar technologies.
However, astute risk managers
recognize the need to do both: making
quick transitions coupled with pragmatic
risk minimization.
The scope of curtailing and/or managing
atmospheric CO2
levels is vast and
from
includes the direct capture of CO2
42 JANUARY 2022 | HydrocarbonProcessing.com
atmosphere, along with planting trees,
shifting to non-fossil fuel technologies,
and capturing CO2
others. Flue gas CO2
nificant portion of emissions. This article
focuses on the processes and projects
to capture CO2
from flue gases.
Post-combustion CO2
involves the removal of CO2
management
from flue
gas, compression, liquefaction, storage
and reuse, where practicable. Several
approaches exist for removing/concentrating
CO2
from flue gas (e.g., absorption,
adsorption, permeable membranes
and cryogenic separation). As shown in
FIGS. 1 and 2, absorption and adsorption
technologies have gained wide industrial
acceptance.
Absorption technologies use organic
amines such as monoethanolamine
(MEA) and its blends. Starting from
MEA absorption, technologies have improved
to minimize several weaknesses
of the MEA process, including oxidation
of the solvent, corrosivity and intense energy
requirements. In recent years, technologies
have focused on adsorptionbased
routes, where CO2
from flue gases
are adsorbed on solid sorbents (e.g., activated
carbon, zeolites and others).
These processes include fixed beds with
solid sorbents, which undergo adsorption
followed by thermal desorption.
Although the adsorption-based technologies
avoid the disposal challenges of
liquid solvents, they still must contend
with the eventual disposal of solid sorbents.
A fluid-bed catalyst process is also
being offered by a technology licensor,
promising lower capital and operating
costs. Unsurprisingly, each process has
its benefits and risks. In addition to the
risks of the carbon capture process from
flue gases, transporting CO2
and storage
risks merit careful consideration, as well.
PITFALLS TO AVOID
The following are six pitfalls to avoid
from flue gas, among
emissions are a sigwhen
developing CO2
Considering CO2
capture projects.
tion. Hastily formulated CO2
capture in isolacapture
projects
could result in missing other
strategically important segments,
cluding CO2
intransport,
long-term storage
and the potential reuse/recycle of
CO2
to stor.
Depending on a plant's location,
infrastructure to transport CO2
age caverns could involve a significant
investment, along with financial and
environmental risks. In the long term,
massive investments are needed in pipeline
and storage infrastructure. Tank and
rail transport-though a viable option
for relatively small quantities-quickly
become uneconomical for large-scale
transports. Each mode of transportation
also has potential risks. Several major issues
to consider include:
* Permitting and right-of-way
considerations: Permitting for
CO2
pipelines involves detailed
application preparation, design
reviews, emergency response plans
and public reviews. Establishing
good public rapport will help
expedite the permit approval
process. Transporting CO2
by
ship and/or subsea pipelines must
comply with several international
codes and regulations and
would require environmental
risk assessment-akin to
those performed for National
Environmental Policy Act (NEPA)
projects. Unsurprisingly, this is a
very rigorous and time-consuming
process. For inland pipelines,
determining a suitable route
requires geo-tech work, including
soil conditions, topography, climate
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