Mitsubishi Heavy Industries Technical Review Vol. 59 No. 2 (June 2022)
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MHI Group's Recent CO2 Capture Technology
for Carbon Neutral Society

KOHEI HIGAKI*1TOMOKI NOBORISATO*2

SHINSUKE NAKATANI*2 TAKURO ONUKI*3

Here is a high level of global interest and social needs regarding decarbonization, andtechnological development in this field is progressing rapidly. We, Mitsubishi Heavy Industries
Engineering, Ltd., have been engaged in the CO2 capture business in response to that trend, andcompleted the commercialization of our new amine-based solvent KS-21TM and received orders forour commercial compact CO2 capture systems as outcomes from the engagement. We are also
considering expansion of various CO2 capture forms such as direct air capture (DAC). We willcontribute to the realization of a carbon-neutral society by adapting the high-performance CO2
capture technologies we have cultivated so far to meet a wide range of social and market needs,
accelerating the development of the technologies, and putting (commercializing) them on themarket.

|1. Introduction
In October 2020, Japan declared its aim to realize a carbon-neutral and decarbonized society
by 2050, and efforts toward decarbonization have been accelerating in the power-generation,industrial and other various sectors. In order to realize a carbon-neutral society, it is necessary to
reduce the amount of CO2 emitted artificially as much as possible, while the CO2 amount that isstill inevitably emitted needs to be offset to zero by absorbing or removing the same amount of
CO2.
Mitsubishi Heavy Industries Group (MHI Group) has made a declaration to achieve carbon
neutrality by 2040, and started efforts with the goal of achieving "Mission Net Zero". This aims to
reduce CO2 emissions (Scope 1 and Scope 2 (Note 1)) by 50% from our group's production activities
by 2030 (compared to 2014 levels) and to achieve net zero CO2 emissions by 2040.
As a company group responsible for social infrastructure, MHI Group specializes not only intechnologies and products that can contribute to controlling and reducing emissions of CO2, agreenhouse gas, but also in technologies and products that capture CO2. Our CO2 capture
technology, KM CDR ProcessTM, leads the world in terms of delivery record, boasting a global
market share of more than 70% with respect to volume of CO2 captured from post-combustion fluegas at commercial plants. We have already delivered the world's largest CO2 capture plant capableof capturing up to approximately 5,000 tons of CO2 per day, and are intensifying our efforts to deal
with large-scale emission sources such as ones in the power generation sector through further
innovation. One of our latest achievements is the commercialization of KS-21TM, our newamine-based CO2 solvent.
In addition, the realization of a carbon-neutral society requires the capture of CO2 not only
from large-scale greenhouse gas emission sources but also from relatively small-scale emission
sources such as ones in industrial sectors. To meet these needs, we are working on the developmentof compact CO2 capture systems with a CO2 capture capacity of 0.3 tons to 200 tons per day that*1

Chief Staff Manager, Decarbonization Business Department, Mitsubishi Heavy Industries Engineering, Ltd.

*2

Decarbonization Business Department, Mitsubishi Heavy Industries Engineering, Ltd.

*3

Plant Engineering Department, Mitsubishi Heavy Industries Engineering, Ltd.

Mitsubishi Heavy Industries Technical Review Vol. 59 No. 2 (June 2022)
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can be applied to various industrial sectors. We are working to realize integrated support fromsystem installation planning to after-sales service in addition to cost reduction and shorter delivery
time by standardizing compact CO2 capture systems so that customers working on decarbonization
can introduce CO2 capture systems more familiarly and easily.
Furthermore, it is expected that negative emission technology, which is a technology to
reduce CO2 that already exists in the atmosphere, will be realized, and we are also working on
direct air capture (DAC), a technology that directly captures CO2 present in the atmosphere.
This report presents our efforts for the early realization of a carbon-neutral society.

|2. New amine-based solvent KS-21TM
2.1

Development process and features of new amine-based solvent KS-21TM

We have newly developed “Advanced KM CDR ProcessTM” as a next-generation version of“KM CDR ProcessTM”, which has proven to be highly reliable through its abundant delivery
record, by making significant improvements including cost reduction. For this Advanced KM CDR
ProcessTM, new amine-based solvent KS-21TM, which was developed in collaboration with The
Kansai Electric Power Co., Inc. (KEPCO) can be used.
The development process of KS-21TM began in 2014 with a two-year screening to findcandidate substances. After that, tests were conducted at the development and research facility andNanko Power Station of KEPCO, while parameter tests, optimal operation tests, etc., werecompleted using pilot equipment in 2019. Then, the demonstration test on KS-21TM conducted in
Norway, one of the most advanced countries in the field of CO2 capture, produced good results in
2021, and the commercialization of KS-21TM was completed with this.
The testing was carried out between early May and late August 2021 at the Technology Centre
Mongstad (TCM) (Figure 1) in Norway, which is one of the world's largest carbon capture
demonstration facility. The performance test of KS-21TM was conducted with the CO2 capture rate
set to 95% to 98% (above the current industry standard of approximately 90%) with regard to fluegas emitted by a gas from the gas turbine at TCM’s test facility. As a result, it was confirmed that
this solvent has excellent energy-saving performance that far surpasses the general amine solvent(MEA : Monoethanolamine) used for chemical absorption methods and is higher than even our
existing amine solvent KS-1TM, as well as that its operating costs and amine emissions (Note 2) arelower. In addition, in the high CO2 capture rate test conducted with the conditions changed, theKS-21TM solvent achieved 99.8%, the world's highest level of capture rate, and succeeded in
capturing CO2 from the flue gas to a level lower than the CO2 concentration contained in theatmosphere (less than 100 ppm). The tests were also performed for flue gas emitted by a fluid
catalytic cracker at the Mongstad refinery adjacent to the TCM, and similar results were obtained. In
addition, in the demonstration test of KS-21TM at the TCM with state-of-the-art testing environmentand high-level expertise, we were able to obtain useful operational data for further improvement andupgrading of KS-21TM, such as the amount of deteriorated substances generated during operationand handling know-how, etc. as well as reliable emission measurement results provided by athird-party organization, which is necessary for future business negotiations in terms ofenvironmental impact assessment. In the future, we will be able to utilize these data for making
applications and obtaining permits/licenses for environmental assessments that are required invarious countries, which will lead to further expansion of business opportunities.

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Figure 1 CO2 capture system at Technology
Centre Mongstad (TCM)
KS-21TM has advantageous features compared to KS-1TM, such as lower volatility and higher
stability against degradation, and is expected to improve economic efficiency for future
deployment, such as by reducing operating costs. Specifically, KS-21TM has the following features.
(1) The lower volatility can significantly reduce the amount of solvent that accompanies
flue gas from the absorber tower and is released into the atmosphere as emissions.
(2) The higher heat resistance allows the regeneration tower to operate at a higher
pressure. As a result, the power consumption of the CO2 compressor installed next to theregeneration tower is reduced significantly and this can lower the equipment cost of the CO2compressor.
(3) The higher oxidation resistance can reduce the amount of solvent that deteriorates andconsumed due to the reaction with the trace components existing in the flue gas. As a result, agreater diversity of flue gas sources can be dealt with independently of the type of flue gas.
(4) The amount of circulating solvent is slightly higher than that of KS-1TM, but thereaction heat with CO2 is lower than that of KS-1TM, which results in more favorable utility
consumption of the CO2 capture system as a whole.
(5) Since we have experience with large commercial facilities, including experience ofscaling up from bench-scale facilities with the conventional solvent KS-1TM, we canimmediately put KS-21TM into practical use.

2.2

Application target of new amine-based solvent KS-21TM

There has been an increasing need for CO2 capture from a wide variety of emission sources
such as biomass power plants, LNG liquefaction plants, cement factories, steel mills, gas engines,
waste incineration facilities, etc. in addition to existing thermal power plants. We are actively
working on basic design, pilot verification, licensing, etc., related to CO2 capture projects in the
power generation and industrial sectors in UK, EU, US, Canada and other regions based on thedelivery record of 13 commercial CO2 plants throughout the world and various technologicalcapabilities. Moving forward, we will expand the application targets of KS-21TM and contribute to
the realization of carbon neutrality, by utilizing its advantages for meeting local regulations withvery strict cost requirements and emission standards.

|3. Compact CO2 capture system
With the growing momentum toward decarbonization in recent years, there is increasing
customer needs for curbing greenhouse gas emissions not only from large-scale emission sources
such as thermal power plants, which have been drawing attention, but also from various industrial
sectors, regardless of the size of the emission source. In order to respond to CO2 reduction

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challenges that our customers are facing and to provide solutions, we are developing compact CO2
capture systems having a CO2 capturing capacity of 0.3 tons to 200 tons per day based on thehighly reliable KM CDR ProcessTM, which has been cultivated with our large-scale systems thathave a CO2 capturing capacity of 450 tons to 4,776 tons per day (Figure 2).
The features of the compact CO2 capture system are as follows:(1) Wide product lineup(2) Low cost and short delivery time due to standardization(3) Simpler sizing due to modular design(4) Integrated customer support from installation planning to after-sales service
We have received an order from Taihei Dengyo Kaisha, Ltd., a plant construction andmaintenance company, for our compact CO2 capture system (CO2 capturing capacity: 0.3 tons perday) to be used for their biomass power plant. The CO2 capture system is designed to achieve a
recycling-oriented and carbon-neutral society by separating and capturing CO2 generated bybiomass power generation and then using it for growing crops and other purposes (Figure 3).

Figure 2

Compact CO2 capture system

Figure 3CO2 capture system with capacity of 0.3 tons per day

Our compact CO2 capture systems consist of modular units that are transported by truck fromthe manufacturing factory and assembled at the installation site, thereby reducing introduction costs
and shortening delivery time. This modular design is applied to all of our compact CO2 capturesystems with a capacity of 0.3 tons to 200 tons per day, so we can accommodate a wide range ofneeds for reducing CO2 emissions even in relatively small facilities. Furthermore, these systems are
expected to be applied to various industrial sectors such as biomass power plants, cement factories,
steel mills, gas engines, waste incineration facilities, etc. in addition to our conventional customers,such as thermal power plants and chemical plants (Figure 4), where efforts to reduce CO2 are
expected to accelerate in the future.

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Figure 4

Application examples of compact CO2 capture system

We will expand our lineup of compact CO2 capture systems to allow the capturing of CO2
from diverse emission sources both in Japan and overseas. Furthermore, complemented byproviding operation support services using our unique remote monitoring system, we will work toestablish integrated customer support from installation planning to after-sales service in the future.

|4. Our approach to DAC
As mentioned above, we have been actively developing CO2 capture from flue gas,
introduced it into society and expanded its market share, and are working on new compact CO2
capture systems.
On the other hand, as the movement toward decarbonization has recently been accelerating
on a global scale, the needs for capturing CO2 from sources other than power plant emissions is
expected to increase in the future as shown in Figure 5.

Figure 5

Required CO2 capture amount per year for realization of carbon neutrality

We are considering expanding various CO2 capture forms such as dry CO2 capture to
respond to such needs, and in recent years we have been developing a system called DAC, which
captures trace amounts of CO2 in the atmosphere.
DAC has a feature to take in the air from the atmosphere as a source from which CO2 isMitsubishi Heavy Industries Technical Review Vol. 59 No. 2 (June 2022)
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captured, so it can be installed anywhere. Furthermore, unlike technologies for reducing CO2
emissions from flue gas, DAC is a negative emissions technology that captures CO2 emitted into
the atmosphere, so we believe that there are few restrictions on its adoption and that it will be
widely accepted by society.
In addition, DAC has a smaller footprint among negative CO2 emissions technologies
currently under consideration and its capacity can be increased relatively easily, so we believe that
this is a promising technology for actual use.
However, DAC also faces several challenges. For example, the concentration of CO2 in theatmosphere is very low (approximately 400 ppm), so capturing highly pure CO2 means treating alarge amount of air, which inevitably results in excessive power consumption and high costs. In
addition, in the case of capturing a small amount of CO2 with high purity, it is necessary tominimize the mixing of air, which is fed to DAC, during treatment, which requires the developmentof precision equipment and accurate system construction.
These challenges will be dealt by taking full advantage of our development know-how in
CO2 capture technology we have cultivated thus far. In particular, reducing the energy consumption
in CO2 capture was one of the most focused factors in the development of technology for CO2
capture from flue gas, and we will seek the possibilities of technological development therefrom. In
addition, we will collect similar development cases not only from CO2 capture technologies but
also from various related fields, and proceed with the development of DAC aiming at its early
introduction to society.

|5. Conclusion
This report introduced our efforts and achievements toward the early realization of acarbon-neutral society. We will expand the application of KS-21TM by continuing efforts to realize
cost reduction and CO2 capture from various emission sources while maintaining the superiority wehave cultivated thus far. For our compact CO2 capture system, we will accommodate needs at
relatively small facilities through taking advantage of their characteristics and establish integrated
support up to after-sales service. We will also continue to develop DAC, which is a promisingtechnology expected to be introduced in actual negative emissions technologies.
Note 1: Scope 1 and Scope 2 in the GHG protocol, which is the international standard for calculating andreporting greenhouse gas (GHG) emissions.
Note 2: A trace amount of amine substance released into the atmosphere from the absorber tower. The
lower this is, the better the technology is with less environmental impact.

References(1)

IEA Net Zero by 2050 A Roadmap for the Global Energy Sector