Partner With Us - Current Themes
Revolutionizing blue carbon evaluation
by visualizing the amount of CO2 in seaweed beds
Underwater CO2 measurement
and evaluation service
Recommended for:
- 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 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.
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.
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.
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.
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.
FAQ
This measuring device uses the non-dispersive infrared (ND-IR) method. The ND-IR method uses two wavelengths — the 4.3 µm band for measurement and the 3.9 µm band for reference — based on a structure consisting of a single light source, optical path, and photodetector. This enables automatic calibration to make highly accurate and stable long-term CO2 concentration measurements possible.
The device is designed under the assumption that it will measure the CO2 concentration underwater. As such, the device can be operated when it is entirely submerged. We have confirmed that the device is waterproof for at least 48 hours at a depth of 1 m underwater using a prototype in a demonstration experiment.
The device has a highly portable, compact design. This means it can be used in various water environments such as the sea surface, underwater, coastal areas, bays, rivers, and lakes.
Using a prototype, we have confirmed that the device can continuously measure for at least 100 hours on battery power. However, the time the continuous measurement is possible varies depending on factors such as the dirtiness of the measurement environment and the operation method.
The major difference is that it is possible to reflect the time, diurnality, seasonal changes, and other elements in the evaluation. This is because it is possible to measure and continuously observe the underwater CO2 concentration. We can expect this to improve the reliability of evaluations. The measured data can also be utilized to analyze the causes of changes in the underwater environment and analyze future predictions and other areas.
Inquiries about the Underwater CO2 Measurement and Evaluation Service
Please feel free to contact us if you are interested in the underwater CO2 measurement and evaluation service that will revolutionize blue carbon credit evaluation by continuously monitoring the amount of CO2 in seaweed beds, or if you want to learn more about this technology.
*This product is under development. Therefore, the specifications are subject to change without prior notice.
Message from the 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.
Notices
-
Paper published on our underwater CO2 concentration measuring device.
-
We have posted the underwater CO2 measurement and evaluation service development theme for which we are looking for collaboration partners.
-
We have published a technical article titled “Supporting Decarbonization with ‘Underwater CO2 Sensor’ and ‘Lightweight Heat Transfer Material Employing Biomass Materials.’”
Inquiries
Please feel free to contact us if you are interested in the underwater CO2 measurement and evaluation service that will revolutionize blue carbon credit evaluation by continuously monitoring the amount of CO2 in seaweed beds, or if you want to learn more about this technology.
*This product is under development. Therefore, the specifications are subject to change without prior notice.
