Al-Qahtani, A. AL-SANAD and V. MULGUNDMATH, Saudi Aramco, Dhahran, Saudi Arabia
Around the world, many nations and
companies are transitioning toward the decarbonization of energy. Aramco has
taken a pivotal role by earmarking strategic initiatives, including its Corporate
Decarbonization Initiative to ensure a sustainable future. This initiative aims
to reduce the amount of carbon emissions that must be captured to reach a
carbon balance or net-zero emissions strategy. One of the key pathways to
reduce carbon emissions is to capture and store (sequester) carbon. To reach a net-zero
carbon balance or net-zero emissions, the inherent carbon from hydrocarbons
that would otherwise be released into the atmosphere as fugitive carbon must be
captured and removed or reused.
Carbon capture and storage (CCS)
technologies capture carbon dioxide (CO2) emissions at the source or
directly from the air. CO2 emissions are then transported away and
stored deep underground or turned into useful products. Capturing carbon has
been practiced for decades to help improve the quality of fossil fuels like
coal and natural gas; however, pioneering next-generation technologies means that
CO2 can be removed and sequestered indefinitely. Research is
continuing to explore new ways to add value to waste CO2 by turning this
waste gas into marketable, low-carbon industrial and commercial products.
Carbon capture technologies can be categorized
as the following: pre‐combustion, oxy‐combustion and post‐combustion (FIG. 1). The
following are definitions of each of these categories:
CCS technologies can be grouped under
three phases in case of deployment: commercially ready technologies, emerging
technologies and concept technologies.
of the ready-deployed technologies are based on post‐combustion CO2
capture and are deployed as part of large‐scale CCS projects at existing power-generation
plants. The deployment of CO2 capture technology has mainly been
focused on low‐cost process emissions-based opportunities, including at power-generation
plants and for industrial applications such as natural gas processing, cement, iron
and steel, and chemicals. Carbon capture processes can be classified according
to their gas separation/capturing principles—namely, chemical absorption,
physical absorption, adsorption, calcium and reversible chemical loops,
membranes, and cryogenic separation.
CO2 capture activities have
mostly focused on power-generation plants (primarily coal‐fired power plants
and gas‐fired power plants), as these make up the largest stationary source of
CO2 emissions. More recently, industrial applications of CO2
capture have begun to gather momentum, mainly in the steel and cement
industries, and, to a lesser extent, in the oil refining and chemicals
CO2 storage involves the
production and recovery of CO2 from industrial processes, and is
typically followed by drying and compression. The captured CO2 can
be injected into depleted oil and natural gas fields for enhanced oil recovery
or sequestered in deep geological formations such as saline aquifers. Alternatively,
CO2 can be used as a chemical feedstock (e.g., for eFuels), curing
in the cement process and algal biofuels production, and chemicals, among other
various ranges of CO2 utilization options.
It is worth mentioning that carbon
capture from gas streams is not new. CO₂ capture technologies based on chemical
solvents (amines) were first commercially deployed in the 1930s to separate CO₂
and other acid gases from methane in natural gas production. Prior to 1972, all
CO₂ captured was vented to atmosphere, except for a small proportion used or
sold for other purposes, such as urea production or beverage carbonation.
The main driver of carbon capture is the
capture cost or the capture abatement in $/MMt of CO2. The cost of
CO₂ capture from low-concentration sources, such as coal-fired power generation,
has reduced by approximately 30%–50% over the past decade due to research and
development (R&D) and economies of scale, and it is decreasing for other
applications, as well. The cost of CO2 capture can vary greatly by
point source and by capture technology. Fuel transformation applications that produce
a concentrated CO2 stream and/or that require CO2 to be
separated as an inherent part of the process (such as in natural gas
processing) have low CO2 capture costs and have been favored for
One of the main factors in carbon
capture, utilization and storage (CCUS) projects is to realize a positive net
present value (NPV) and to find cost-effective ways to design, operate and
maintain the CCUS project. Due to the low commercial utilization of CO2,
most CO2 projects would depend on permanent sequestration.
To make the CCS business attractive, several
cost-effective approaches should be considered. The following are some
considerations to help the economics of the business.
of the sequestration sink. One
of the key requirements to optimize the cost of any CCS project is to allocate
the nearest, best-fit candidate sink to reduce the required pipelines, distance
and compression requirements. The overall costs will be reduced further if pressure
requirements for transporting CO2 are reduced, and if higher-capacity
pipes and the nearest sinks from the emitters’ sources can be identified. Mostly,
such privileges with ideal sinks are unavailable, but the best-fit candidate would
have ideal conditions to design and safely operate the CCS process with the optimum
cost during the lifetime of the project.
Although the most popular sink for
100% permanent CO2 sequestration is a saline aquifer, other types of
sequestration are also assessed and used around the world. A detailed
assessment of the subsurface and its associated risks could optimize the cost at
the full value chain. For example, any potential of lowering pressure in the
candidate sink would affect the cost of the capture and transportation, and
possibly optimize power requirements.
of the design philosophies to reduce the capital expenditure (CAPEX) of a CCS
project is to capitalize on the existing infrastructure of the facilities, (rotating
and stationary equipment, pipelines, etc.). This can be achieved by reusing existing infrastructure
safely for CO2 transport and storage.
If capitalizing on the existing
infrastructure provides good outcomes to optimize CAPEX, several considerations
should be accounted for before any repurposing of existing infrastructure for CO2
transport and sequestration. Some of these considerations could include
installing new equipment or monitoring systems, which would add additional costs.
Several physical, chemical and process
engineering aspects should be assessed to ensure the compatibility of the
materials and equipment to adopt the modified process safely and economically. The
integration of the infrastructure at existing facilities with the CCS value
chain (or segment) could help to reduce CAPEX. For example, facilities with a huge
inventory, and with tank farms associated with triethylene
glycol (TEG) systems, could be an opportunity
to favor TEG dehydration in the capture part. That would also reduce the need for
new chemical tanks and could optimize the cost of dehydration units, leading to
a reduction of the overall facility’s footprint.
reduce the cost of CCS, sharing the infrastructure concept among several
emitters could provide the most cost-effective approach. Infrastructure sharing
of stationary and rotating equipment would provide a significant cost
reduction. One tactic is sharing pipelines and final compression (pumping) of the
captured CO2 through dedicated hubs. In doing so, there is a huge
potential of reducing the overall CAPEX and operating expenditure (OPEX) for
The sharing concept is not limited to
pipelines and equipment—it could also be extended to several applications, such
as cooling water, relief systems, utilities, store houses, maintenance yards
and others. In addition, the concept of remote operation and centralized
maintenance would help to enhance OPEX. Another benefit of sharing the main
infrastructure is the ability to modularize and standardize equipment and
pipelines. Care should be taken that each emitter does not breach the CO2
specifications ahead of transporting or pumping it to the subsurface.
In all, the sharing concept would help
reduce the overall cost of the project in both CAPEX and OPEX.
to develop new technologies. One
of the long-term solutions to optimize CCS project cost
is leveraging the investment of innovation and deploying new cost-effective
technologies. A breakthrough in any segment of the value chain would impact the
total cost of the project. For example, employing special coatings, alloy materials
or cost-effective materials in pipelines could optimize several segments and
units of the value chain, such as eliminating or reducing maintenance on dehydration
Another aspect that makes the CCS
business attractive is the development of new applications for CO2 utilization.
Finding a market for CO2 utilization would positively impact the
economics of the CCS project. For such cases, the business could profit by
increasing the value and purity of CO2 through increasing the demand
on CO2 supply.
mechanisms. As the market for
CO2 is limited and utilization is minimal, the only way to get CCS projects
deployed is through incentive mechanisms and stringent policy regulations for
mitigating CO2 emissions. In all the existing projects and operating
facilities, policies are essential for running a CCS business. Regulations, carbon
emitting taxes and other means of incentives should be considered for current
projects. Utilizing carbon credits and carbon trading
and unlocking a blue ammonia business could comprise supporting mechanisms for the
CCS business, as well.
The authors believe that CCS has the
potential to significantly reduce global emissions. It is a central element to
support the decarbonization of oil and gas business and operations. It is also
an essential element of an integrated ammonia and H2 production program.
In addition, CCS has the potential to contribute to the Saudi Green Initiative’s
goals of reducing greenhouse gas emissions, and to support the economic
diversification and sustainable development of the country’s economy. HP
AYIDH AL-QAHTANI is a
Process Engineer at Saudi Aramco’s Energy Transition Engineering Department
within the Hydrogen Systems Engineering Division in Dhahran, Saudi Arabia. He
is a chemical engineer with 6 yr of experience in engineering services and technical
support, and has worked in gas plant facilities, including acid gas removal, dehydration
and sulfur recovery. Al-Qahtani has been involved in operations, process and
technical support, and has led gas plant startups from pre-commissioning to gas
production. Al-Qahtani has also earned a Fundamental Engineering certificate.
is a Process Engineer
at Saudi Aramco. He works with the Process and Control Systems Department
within the Flare and Relief Systems Group. He has 8 yr of experience. Al-Sanad has
been involved in major tasks at the company, such as NGL recovery plant
commissioning and Saudi Aramco’s decarbonization strategy development. He has
also led several milestones in the company’s flaring minimization programs. He
earned a BS degree in chemical engineering from King Fahd University of
Petroleum and Minerals (KFUPM).
VINAY MULGUNDMATH is an Engineering Specialist within Saudi
Aramco’s Energy Transition Engineering Department’s Hydrogen Systems
Engineering Division. Prior to joining Aramco, he held the role of Chief Technologist
at the Net Zero Technology Centre in Scotland. He has also been a board member
of the Scottish Environment Protection Agency (SEPA) and the Scottish Energy
Advisory Board. Dr. Mulgundmath is a non-executive advisor to the Scottish
Carbon Capture & Storage research group, and to Scotland’s Hydrogen
Accelerator at the University of St. Andrews. He is also an honorary administrator
at the University of Aberdeen’s Directorate of Research & Innovation. He
earned an MS degree in process engineering, and a PhD degree in chemical engineering
with a specialization in post-combustion carbon capture technologies.