Expanding the ideas of carbon recycling. Challenge to capture CO₂ “efficiently” and “anywhere”

CO₂ has always been viewed as a negative thing, and even more so as more and more people around the world strive to achieve carbon neutrality and zero carbon emissions. However, CO₂ will actually play an important role to realize a carbon-neutral world. In addition to measures aimed at reducing and eliminating carbon emissions, “carbon recycling”, which captures and reuses CO₂, is underway. At first, let’s explore the background story.

The introduction of renewable energy and the transition from conventional fuels to electric or hydrogen-based energy have made progress around the world in order to achieve carbon neutrality by 2050.

At first, it is necessary for power generation sector to reduce carbon emissions. In addition to that, it is also necessary for other sectors to convert their conventional energy to those which does not emit CO₂, such as electricity and hydrogen. And other measures are necessary in the field where utilizing electricity or hydrogen cannot reduce carbon emissions enough to decarbonize it and thus it can’t help emitting CO₂.

These measures are based on the technologies for capturing CO₂. They can separate CO₂ and other substances in the exhaust gas of factories or in the air to capture it. It can be used to make chemicals, fuels and the like with the technology of CCU, Carbon dioxide Capture and Utilization, and also to store the CO₂ deep in the ground with that of CCS, Carbon dioxide Capture and Storage.

The technology of CCUC, Carbon dioxide Capture, Utilization and Storage, is collectively used to refer to that of CO₂ capture, storage and utilization. It is expected to capture not only CO₂ that will be emitted in future, but also CO₂ that was emitted by human beings in the past utilizing these technologies. It is essential to capture and recycle CO₂ to build the energy recycling society. Efforts in this field is underway around the world.

DENSO’s Minoru Morisaka explains the kinds of efforts on CO₂ capture that are currently underway around the globe.

“Carbon capture technologies for high-concentration CO₂ emissions from power plants, industrial factories and the like are mainly being undertaken by heavy industry companies, and these technologies can capture CO₂ with low energy costs.

On the other hand, CO₂ is emitted from many other sources. Overseas startups are taking on the technological development to capture low-concentration CO₂ that is in the air or is emitted by vehicles and households.

However, these technologies have a problem that they still require much energy to capture CO₂. Using large amounts of energy to capture CO₂ will prevent us from achieving carbon neutrality.”

DENSO is utilizing its technologies that it has developed in the auto industry so far to create a compact and high-efficient CO₂ capture system in the field where energy cost of CO₂ capture and concentration of CO₂ is a trade-off.

Morisaka continued:

“In order to promote widespread carbon recycling throughout society, it’s important to make CO₂ capture possible in a wider range of locations, and with less energy. The truth is that manufacturing, transport, and other human activities generate massive amounts of CO₂ emissions, even though their concentrations are low. We must be able to capture these emissions economically in order to realize our goal of carbon neutrality, and that means the energy used to capture low-concentration CO₂ emissions must be less than energy gained through emissions capture. Moreover, in order to minimize CO₂ emissions resulting from the transport of captured CO₂, it’s necessary to ensure that capture systems can be used in nearby locations for all users.

By creating a compact system that can capture low-concentration CO₂ efficiently and be used anywhere, it will be possible to capture CO₂ on building rooftops, in homes, and all sorts of other locations, and thus change the way people view CO₂ in general.”

DENSO is utilizing a new capture method in the systems it is developing in order to enable CO₂ to be captured “efficiently” and “anywhere”.

Conventional CO₂ capture devices use a heat-based thermal approach, which involves capturing CO₂ through temperature increases and decreases. However, this approach requires large amounts of energy for heating and cooling, and typically the capture systems must be large to be loaded with heaters, heat exchangers and other such components.

Kenji Tani, who is involved in CO₂ capture technology and system development at DENSO, explains the advantages of the company’s system.

“We are developing the CO₂ capture technology called electric-field approach utilizing our technologies for vehicles. The electric-field approach captures CO₂ in a way that switches the voltage, not raises or lowers the temperature.
As we can operate it suitably by switching the voltage, the energy costs for capture operations are low, and the system can be made small as the unit does not require heating and cooling equipment.”

“DENSO’s elemental technologies it has developed over the years have made this electric-field approach possible. We’re leveraging all of our air, heat and electric power management technologies, as well as our wide range of expertise in ceramic catalyst manufacturing, to build this system.
In addition to elemental technologies, we also have our expertise in system optimization for both hardware and software factors, as well as our production technologies for mass-producing high-quality products at low cost.
By bringing together all of these strengths, we will complete and popularize our small-sized and high-efficiency CO₂ capture system.”

DENSO is currently carrying out in-house demonstration experiment on its CO₂ capture system. It will carry out social demonstration experiment in 2023.

According to Tani,

“Through repeated demonstration experiments, we will build up knowledge in this field and improve our product. Because our CO₂ capture system is very compact, it has the potential to inspire a wide range of ideas for usage, such as installing it on building rooftops to capture CO₂ and then using that CO₂ for the building. For this particular idea to work, we’re considering designing a capture unit that’s small enough to fit inside an elevator.
Moving forward, we want to figure out which usage locations are best suited to user needs, and to try installing units to see how things work in practice. We will continue to gather feedback and ideas from the market and our partners in the project as we carry out demonstration experiment together.”

DENSO’s Kurumi Usuki, who is actively negotiating with various companies, talks about her vision for CO₂ capture and its subsequent future, saying that she aims the future where CO₂ is naturally utilized.

“CO₂ can be used in various ways. There has already been its demand for use, and the earliest way to make it true is to use CO₂ directly. CO₂ is used to process food and to make dry ice, and it means that captured CO₂ can be handled as useful products. Our goal is to help CO₂ capture spread quickly, which is why we’re actively seeking project partners and collaboration for direct applications.

In addition to using CO₂ directly, we look ahead to recycling it for other applications. Various possibilities for their utilization are attracting attention, and they include production of chemicals such as plastics, usage as alternative fuels such as natural gas, and conversion to minerals.”

“However, technologies related to hydrogen and other such substances are also necessary for carbon recycling to succeed. We have a hydrogen-related development team in the same division here at DENSO, so we plan to collaborate with them while brainstorming with partner organizations to determine optimal recycling methods and approaches.”

DENSO’s project team is taking a two-pronged approach, such as finding the earliest way to put captured CO₂ to use and identifying the best carbon recycling methods for captured CO₂ in the long term. With this approach, the team is working hard to change what people think of CO₂ while also providing practical options for users. Tani commented,

“CO₂ is not our enemy. If we can use it effectively, we can make major progress toward the goal of carbon neutrality. At DENSO, we hope to harness technological developments to turn CO₂ into something positive while encouraging society to focus on and take on carbon recycling.”

DENSO has been taking on new challenges of carbon recycling. Morisaka explains why the company has been tackling such a difficult challenge.

“As an automotive system supplier, DENSO has supplied innumerable products worldwide. We always try our best to create systems with excellent environmental performance and minimal CO₂ emissions, but that doesn’t change the fact that the cars which use our systems emit CO₂, and our product manufacturing processes do the same. Therefore, we hope to utilize technologies developed right here at DENSO to effectively capture and recycle the CO₂ generated by our business activities and products in the past, as well as emissions from future activities and products. This is our responsibility as a company.”

DENSO is making full use of its technologies to create a small-scale distributed CO₂ capture system. The aim is to harness the flexibility provided by this design to expand the scope of potential locations where systems can be installed while trying out a wide variety of potential usages for captured CO₂. It may realize a local-production-for-local-consumption of CO₂, which captures CO₂ emissions form households, commercial buildings and other sources and utilize them depending on a diverse array of applications.

This is not something DENSO can achieve by itself alone, which is why it is working closely with various partners on large-scale carbon recycling processes with the goal of carbon neutrality.