Development of a measuring device that
makes it possible to visualize the amount of
CO₂ in seaweed beds "Underwater CO₂
measurement and evaluation service"
revolutionizes evaluation of blue carbon We are looking for partners who want to work with us to address social issues
related to the ocean, such as restoration of seaweed beds, utilizing a sensor
that enables accurate and continuous measurement of underwater CO₂ concentration.

Description

Partners who want to work with us to achieve sustainable and rich oceans that can be passed on to future generations, by restoring seaweed beds and addressing other social issues related to the ocean
Products used

An underwater CO₂ measurement and evaluation service utilizing an NDIR-type underwater CO₂ concentration measuring device that can be installed anywhere and achieves high reliability through automatic calibration
*This product is under development.Therefore, the product specifications are subject to change without advance notice.

MATCHING
POINT

・Companies, organizations, local governments, and others interested in restoration of seaweed beds and creation of blue carbon credits
・Companies, organizations, local governments, and others looking to expand their business in coastal regions
・Companies, organizations, and others exploring new business models through visualization of marine environments

Blue carbon uses marine ecosystems to sequester carbon in the ocean, and is attracting attention as a new trump card in measures against global warming. It holds great potential, and carbon credit trading is also advancing. However, issues remain in methods for evaluation of CO₂ absorption, and the blue carbon market has yet to achieve the anticipated growth. To overcome this situation, Murata Manufacturing is advancing the development of an underwater CO₂ concentration measuring device capable of direct and continuous measurement of underwater CO₂. Our goal is to achieve widespread adoption of a service that directly measures and evaluates the amount of CO₂ absorbed by seaweed beds based on a new evaluation method utilizing this device. We are looking for collaboration partners who will join us in utilizing this new solution to boost blue carbon creation activities.

Contents

Blue carbon has both great potential and challenges
Aiming for a service that directly measures and evaluates CO₂ absorption by seaweed beds
Towards a future where we can contribute to the preservation of marine environments and creation of sustainable marine businesses
Message from the "Underwater CO₂ concentration measuring device" developers

Blue carbon has both great potential and challenges

Enormous potential of blue carbon for decarbonization

Carbon that is absorbed by marine ecosystems and sequestered in the ocean for long periods is called blue carbon. In particular, seaweed beds composed of seagrass and seaweed such as eelgrass, kelp, and wakame have high CO₂ absorption and carbon sequestration capability comparable to that of forests on land, making them important reservoirs for blue carbon. Due to their high potential, seaweed beds are also considered a key decarbonization measure, but they are exhibiting a steady decline, making conservation and restoration an urgent issue.

The challenges are the accuracy and effort of evaluating seaweed beds

Decarbonization measures using blue carbon hold great potential, and trading has also begun in Japan under a system called "J Blue Credit®." This system currently evaluates seaweed beds using the following method based on multiplication of seaweed bed area, seaweed bed coverage (density), and absorption coefficients.

Current main methods for evaluation of seaweed beds

Seaweed bed area and coverage (density) are measured through visual observation by drones or underwater by divers. After accurately understanding the vegetation distribution of the target seaweed bed, values obtained from literature are then used to estimate the absorption amount by combining the CO₂ absorption capability of each species. Current evaluation methods face challenges in terms of the effort needed to manually survey extensive seaweed beds, and accuracy due to the use of literature values, and advanced specialist knowledge is also required.
To realize international carbon credit trading, a simpler, objective, and quantitative evaluation method is needed. Therefore, Murata launched a project to realize a convenient and highly accurate underwater CO₂ concentration measurement service. And now, some four years since the project's inception, we have succeeded in demonstrating the underwater CO₂ concentration measuring device that is the key to spreading this service.

Aiming for a service that directly measures and evaluates CO₂ absorption by seaweed beds

Standalone, maintenance-free underwater CO₂ concentration measuring device

Continuous measurement of CO₂ concentration in the ocean is essential for quantitative evaluation. This calls for a measuring device that can be left for long periods, but normal measuring devices experience a phenomenon called "drift" in which measurement values change gradually with prolonged use. This occurs due to factors such as deterioration of components over time and cannot be eliminated, so regular, manual calibration is required.
However, Murata has developed an underwater CO₂ concentration measuring device, based on our CO₂ gas sensor, that achieves automatic calibration by using the two wavelengths of 4.3 µm (measurement light) and 3.9 µm (reference light) with a structure consisting of a single light source, optical path, and photodetector. This achieves both long-term stability and high measurement accuracy, enabling continuous maintenance-free operation.

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Murata CO₂ gas sensor capable of automatic calibration and correction

The measuring device is also provided with waterproof performance designed for underwater measurement. This enables continuous measurement not only at the ocean surface but also with the measuring device completely submerged underwater.

Successful visualization of changes in underwater CO₂ concentration

To measure the underwater CO₂ concentration, it is necessary to equalize the underwater CO₂ concentration with the CO₂ concentration inside the measuring device. In order to quickly achieve this concentration equilibrium, the underwater CO₂ concentration measuring device uses a gas-permeable membrane with a large surface area on the gas balancer. This enhances the efficiency of gas uptake into the measuring device, enabling responsive measurement of CO₂ concentration in the ocean.
In addition, the compact design with excellent portability makes it possible to submerge not just the probe part but the entire device in the ocean. This allows for continuous and direct measurement of CO₂ concentration, making it possible to understand continuous changes in underwater CO₂ concentration, which was previously a challenge to measure.

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Change in CO₂ concentration in the ocean
Verified data from Tamanoura Bay, Goto City, Nagasaki Prefecture (conducted in March 2025)

Paper Published on
Our Underwater CO₂ Concentration Measuring Device

A paper co-authored by Shizuoka University, the Port and Airport Research Institute, and Murata, titled “A Compact pCO₂ Measurement System Using a Gas Permeable Membrane for Underway and Moored Observations in Coastal Waters” was published in the “Environmental Monitoring and Assessment” international environmental monitoring journal on November 17, 2025.
This paper reports on the results of a comparative test with sensors from other companies through continuous underway observations in Tokyo Bay and a comparative test with analysis of water sampled during moored observations in Komuke Lagoon in Hokkaido. Through these results, the paper demonstrates that the underwater CO₂ concentration measuring device developed by Murata has comparable measurement accuracy. The paper also shows that our device offers several advantages, including a compact size, easy portability, and low power consumption. To read the paper, please visit the link below.

Details of the paper

Seeking to create a market by providing an evaluation service

Murata's goal is not to merely develop and sell the underwater CO₂ concentration measuring device, but to offer a comprehensive evaluation service. We seek to address the issues facing blue carbon creation activities, and enable quantitative evaluation of CO₂ absorption by seaweed beds, which was previously a challenge. We also hope to build a foundation for sustainable blue carbon creation activities, and create a market.

Towards a future where we can contribute to the preservation of marine environments and creation of sustainable marine businesses

Scenes from field tests

Field tests conducted on a nationwide scale

Four years have passed since the launch of this project, and we are currently conducting field tests on a nationwide scale from Hokkaido to Okinawa. Our network is gradually expanding through collaboration with local fisheries cooperatives and others, and we are also continuing efforts to improve the measuring device, such as by extending measurement time and improving accuracy.
Murata hopes to see this measuring device utilized by even more people to achieve both preservation of the marine environment and expansion of the blue carbon market.

A new marine business model realized through collaboration

Murata offers CO₂ measurement technology that enables easy and highly accurate measurement with stable long-term operation, as well as analytical technology. Through this, we hope to overcome the current tradeoff between accuracy and effort, and to work together with many related parties to establish methods for evaluating blue carbon and provide an evaluation service.
Murata's goal is to collaborate with a wide range of partners, including seaweed bed restoration businesses, and to play a part in creating business mechanisms. Our foremost desire is to maintain and restore seaweed beds, and ultimately leave the best marine environment possible for future generations.
We aim to not only provide technology, but to work together with partners to create new value to realize sustainable marine businesses and develop a healthy blue carbon market.

Inquiries

Murata is looking for partners who seek to evaluate the amount of CO₂ absorbed by seaweed beds utilizing our underwater CO₂ concentration measuring device.
If your company is interested in this service, please feel free to contact us using the inquiry form.
*This product is under development.Therefore, the product specifications are subject to change without advance notice.

Murata Manufacturing Co., Ltd. Corporate Technology & Business Development Unit

Message from the "Underwater CO₂ concentration measuring device" developers

Murata Manufacturing Co., Ltd.
Corporate Technology Planning & New Business Development Group
Corporate Technology & Business Development Unit

Yoshiyuki Nishihara Masako Tenpaku: The ocean is called the final frontier of visualization, and remains a region with much less information compared to land. We have actually only recently come to understand that the underwater ecosystem contributes as much or even more to carbon sequestration than land. Murata hopes to contribute to visualization and sustainable use of the ocean through the use of this underwater CO₂ concentration measuring device. If you are involved in CO₂ concentration measurement and seaweed bed restoration and are interested, please feel free to contact us. We sincerely look forward to meeting partners who will work with us to open up a new future.
Furthermore, underwater CO₂ concentration is also deeply related to organisms such as fish and shellfish, making this technology potentially useful not just for blue carbon but also in a wider range of fields. If you have any requests, or would like more information - not only on the ocean, but also rivers, lakes, and other water environments - please feel free to consult with us.