Carbon Capture Technology:
Options and Developments
Why do we need Carbon Capture?
 Among greenhouse gases, carbon dioxide accounts for
94% of the total greenhouse gas emissions, and over 80%
of the anthropogenic CO2 emissions in the world is
generated through energy production based on fossil
resources.
 Typically, three technical options are considered for the
reduction of CO2 emissions:
 Decreased energy consumption and more efficient energy usage
 Development of renewable energy sources and non-fossil fuels
such as hydrogen
 Development of capture and sequestration technologies to trap
more CO2 underground or in the ocean
Carbon Capture and Storage (CCS):
What is it about?
• Every year, we generate approximately 10 billion tonnes of
carbon emissions, through our consumption of fossil fuels and
land use changes.
• A significant portion of that comes from power generation and
industrial sectors like steel and cement production, paper and
pulp production and the chemical industry.
• For a lot of these industrial processes, there are no substitutes
available to reduce the emissions generated.
• Even renewable energy technologies may not be enough to
support our continually growing energy demand, meaning a lot
of these fossil fuel demands will continue for at least the next
few decades.
Carbon Capture and Storage (CCS):
What is it about?
• This is where CCS comes in, an approach otherwise
known as carbon capture and storage.
• This technology is also sometimes referred to as CCUS,
which is carbon capture, utilization and storage.
• Whether the ultimate plan is for long-term storage, or for
long-term utilization, this technology aims to capture
carbon emissions generated from single point sources, like
a coal-fired power plant or a natural gas processing
facility.
Carbon Capture and Storage (CCS):
What is it about?
• In general, CCS relies on three main activities;
• Carbon capture
• Carbon transport
• Carbon storage
• Carbon capture is usually the separation of CO2 from the
emissions (originating from coal fired power plants/natural gas
processing plants) to prevent its release to the atmosphere.
• Pure CO2 is captured so it can then be pressurized, and
become suitable for the next stage in the process, transport.
Transport usually occurs in pipelines, similar to the
infrastructure we use today to move natural gas around.
• Once the CO2 has been transported to a suitable location, it
can be stored. This is the final stage of carbon storage.
Challenges
• CCS is contentious as an emission reduction option.
• CCS will be one tool in a suite of emission reduction tools.
• We cannot move away from fossil fuels for at least several
decades.
There are some who argue that using CCS allows the fossil fuel industry to continue developing when
we should be looking at alternatives. The truth is, we are still looking at alternatives. Ideally, at some
point in the future, we will have found zero emission fuels for all of our economy’s needs.
Unfortunately, that future is likely still decades away. If we want to meet global emission reduction
targets in time to limit dangerous climate change, then we need to decarbonize as quickly as
possible, and much faster than what we are doing now. That is why CCS is so important - it allows our
industry and power generation sectors to decarbonize while the rest of our zero emission technology
develops.
Global CO2 Emission Reductions in
IEA Scenarios
Status
• At the beginning of 2018, there were 22 large-scale CCS
facilities in operation or under construction globally.
• These facilities can store a total of 40 million tonnes per
annum of CO2 that otherwise would have entered the
atmosphere.
• This is the equivalent to taking more than eight million
passenger vehicles off our roads.
• A further 15 projects are in various stages of planning
development, and once completed, could contribute to an
additional 25 million tonnes of CO2 capture.
What is it that CCS needs in order to
be successful?
• CCS needs;
• Source
• Link
• Sink
• The source is the capture part - something like a coal-fired
power station.
• The sink is the storage or sequestration part - so this depends
on having the right geological conditions for storing and
trapping CO2.
• The link is the transport part - the pipeline that is needed to
transport the compressed CO2.
What is it that CCS needs in order to
be successful?
• CCS is a challenging technology. It requires lengthy and
expensive exploration to identify the optimal storage locations,
even before the lengthy and expensive process of building
carbon capture technology can begin.
• However, it has enormous potential to reduce the growing
global greenhouse gas emissions and is the only technological
solution we have today for a number of carbon intensive
industrial processes.
• It is also the only technology that can actively reduce CO2
levels in the atmosphere.
CO2 Capturing Modes
 While CO2 capture technologies are new to the power
industry, they have been deployed for the past sixty years
by the oil, gas and chemical industries.
 They are an integral component of natural gas processing
and of many coal gasification processes used for the
production of syngas, chemicals and liquid fuels. There
are three main CO2 capture modes for power generation.
 Post-Combustion
 Pre-Combustion
 Oxyfuel Combustion
Post Combustion Carbon Capture
Technology
 Post combustion carbon capture aims to capture the emissions
that exit a plant via the chimney or stack, and then separate the
CO2 by using chemical or physical sorbents to selectively
remove CO2 from the gas mixture.
 The emissions generated in the combustion of fossil fuels are
known as ‘flue gas’, and generally comprise a mixture of fly
ash, water vapour, carbon dioxide, nitrogen oxides, and sulphur
oxides, as well as other particulates.
 Because the fuel is combusted in air, which is around 70%
nitrogen, around two-thirds of the flue gas is nitrogen. The
process of CO2 separation from the flue gas stream is quite
challenging. It can be an energy intensive process and
requires somewhat costly materials.
Post Combustion Carbon Capture
Technology
 Typically, in the power generation process, the fly ash, SO2 and NO2
must be removed first, as these materials can degrade the solvents
that capture the CO2.
 Once these materials have been removed, the remaining flue gas
passes through a solvent or sorbent that captures or absorbs the
CO2 and later releases it in a concentrated stream.
 The CO2 absorption and release process is generally temperature
dependent. Having the flue gas pass through the solvent at one
temperature allows the CO2 to be absorbed, then changing the
temperature allows a concentrated CO2 stream to be released, to be
either stored or used for some other purpose.
 The treated flue gas, now mainly nitrogen and water vapour, is
released to the atmosphere.
Post Combustion Carbon Capture
Technology
 As a process for reducing emissions of fossil fuel
technologies, PCC has a number of key advantages.
 It can be retrofitted to existing coal and gas power plants
as well as many industrial plants as an “end of pipe”
solution, allowing emission reduction of a number of
industrial processes that do not yet have zero emission
substitutes.
 It can also be used for partial capture and configured to
treat only part of the flue gas stream.
Post Combustion Carbon Capture
Technology
 There are two well-known commercial scale examples of
successful application of PCC technology.
 The Boundary Dam PCC project has been operating at 1
million tonnes CO2 capture scale since 2014, using an
amine solvent process to capture CO2 from a coal-fired
power plant in Saskatchewan, Canada.
 The Petra Nova PCC project has been operating at 1.4
million tonnes CO2 capture since 2017, using a different
but similar amine solvent process to capture CO2 from a
coal-fired power plant in Texas, USA.
Post Combustion Carbon Capture
Technology
 Although there are examples of operational success, there are
still a number of challenges in the development and
deployment of PCC. This technology has high capital cost
requirements, especially in the CO2 absorption system.
 Operating costs are also relatively high. This is mainly
associated with the replacement of and the amount of energy
required for regeneration of the solvents used in the CO2
extraction process.
 There are also challenges in scaling up to meet the size
requirements of
large-scale operations. Some PCC
technologies are currently available at only relatively small
scale.
Oxy Combustion Carbon Capture
Technology
 Oxy-combustion capture provides a clever solution for
reducing our emissions intensity of fossil fuel combustion.
 Oxy-combustion, or oxyfuel as it is also sometimes known,
is an “in-process” carbon capture method.
 That is, changes are made to the normal internal
combustion process to produce a concentrated CO2
stream.
Oxy Combustion Carbon Capture
Technology
Oxy Combustion Carbon Capture
Technology
 In a power generation boiler, pure oxygen is generated in an air
separation unit, which is then used to combust the fuel. The
produced flue gas now contains a high concentration of CO2 as
there is no longer nitrogen coming in with the combustion air.
 Some flue gases are recycled back into the combustion
process. This provides necessary dilution of pure oxygen to
control combustion conditions, as burning fuel in completely
pure oxygen results in combustion temperatures which are
unacceptably high.
 A CO2 purification unit then removes any leftover impurities
from the CO2 rich flue gas so it can be pressurized for
transport and storage.
Oxy Combustion Carbon Capture
Technology
 Unlike post-combustion capture, oxy-combustion capture
doesn’t use solvents or sorbents in the CO2 capture process.
 This makes the process relatively simpler, and allows for a
range of advantages over other carbon capture methods.
 Oxy-combustion capture has following advantages;
Retrofitting
Slightly improved efficiencies
Lower non-carbon emissions
Possibility to be either a net zero use of water of even production of
water
 Synchronous power generation technology
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Oxy Combustion Carbon Capture
Technology
 Significant-scale demonstration of first generation oxycombustion technology on coal-fired power generation has
already occurred.
 Callide Oxyfuel successfully demonstrated carbon capture in
2015 in Central Queensland, Australia
 Ciuden Compostilla Oxyfuel 30MW demonstration from 2009 to
2012 in Spain
 Scharze Pumpe Oxyfuel from 2008 to 2014 in Germany
Oxy Combustion Carbon Capture
Technology
 Challenges
 Scalability
 High Capital Costs
 Operating Costs
 All-or-nothing deployment on a unit
 Requirement of air-fired combustion for initial start-up
 Suitable storage sites
 Difficulties in retrofitting because of large space requirement for
air separation unit and CO2 purification
Oxy Combustion Carbon Capture
Technology
 Without development happening now, there may be
insufficient time available to take the technology to
technical and commercial maturity in the 2030-2035
timeframe needed for emission reduction.
 Developing oxy-combustion can be expected to take 10 to
15 years, even on an aggressive, well-funded schedule.
Pre Combustion Carbon Capture
Technology
 Pre-combustion carbon capture is a “within-plant” process.
 That is, the treatment that allows a concentrated CO2 stream to
be created happens within plant processes.
 Like post-combustion capture, solvents or sorbents are used to
extract CO2 and prevent its release to the atmosphere. Like
post-combustion capture, solvents or sorbents are used to
extract CO2 and prevent its release to the atmosphere.
 Pre-combustion capture is different however in that the
treatment happens prior to combustion rather than after, and
can only be used on particular fuels.
 The processes involved in pre-combustion capture are rather
complex.
Pre Combustion Carbon Capture
Technology
 The fuel source, whether coal or gas, must be converted
into syngas, a mixture of hydrogen, carbon monoxide,
carbon dioxide and water.
 This happens from combining fuel and almost pure oxygen
in a gasifier, a process known as gasification.
 This is a process commonly used across a range of
industrial processes. The syngas is then reacted with
steam in a ‘shift reactor’, to produce hydrogen and CO2.
 By applying either a chemical or physical wash, the CO2
can be extracted, and the hydrogen is then used to power
the turbine and generate electricity.
Pre Combustion Carbon Capture
Technology
 Alternatively, gaseous fuels such as natural gas are often
obtained from underground sources where they are present in
mixtures of other gases such as CO2.
 This chemical washing process is already in use at large scale
at the Sleipner natural gas production facility in the North Sea,
offshore from Norway. This plant has been in operation since
1996, and has been conducting safe and reliable removal and
storage of nearly one million tonnes of CO2 per annum in deep
saline geological reservoirs.
 Another example of pre-combustion capture at large scale is
the Century Plant in Texas, USA, where up to 8.4 million tonnes
per annum of CO2 is captured in a natural gas processing
facility and used for enhanced oil recovery within oil reservoirs.
Pre Combustion Carbon Capture
Technology
 Advantages
 Commercially available
 Lower efficiency losses, 7-8%, as compared to post combustion
capture technology (10-11%)
 Lower water demand, as compared to post combustion capture
technology
 Generation of hydrogen as byproduct – additional profit
opportunities
Pre Combustion Carbon Capture
Technology
 Challenges
 Challenging retrofitting (binding to IGCC)
 IGCC not yet widely used
 High capital costs
 High operating costs