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Introducing IoT & AI to Provide Ideal Conditions for Seaweed CultivationIzuru Senaha

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Previously, we discussed the circumstances behind the Project for seaweed cultivation using CO2 dissolution equipment. Yet, more innovation is required to realize the concept of a recycling society. Professor Senaha talked with us about innovation related to seaweed cultivation.

Elements Which Affect Seaweed Growth

We continued our research because we believed that seaweed cultivation was the best way to utilize CO2.
Dissolving CO2 in seawater activates photosynthesis in seaweeds, so we started tests using a red variety called Solieria robusta (mirin). After 1 month of blending CO2 into the tank, the seaweed showed growth 4 or 5 times greater than the tank without added CO2. By the way, the 1 month growth period isn’t a strict rule. We learned that we could expect significant growth in a short 1-month period using CO2.

Another thing we learned is that we got better growth results when we changed the flow of the seawater. We spent another month to test and compare tanks with and without a current flow, and this also showed 5 or 6 times greater growth.

My research specialty is heat and mass transfer, so I understood that this project was demonstrating another very similar phenomenon. In summer, the wind from a fan feels cool because the air carries heat away from the surface of our bodies. CO2 and other nutrients inside seawater are also substances that behave this way. If the current is flowing, then both substances and heat can move around with equal ease. This principle is the same as heat and mass transfer. We saw that a proper current allows for nutrients and CO2 to move across the surface of the seaweed for easier adsorption. More water flow around the seaweed means better adsorption, but extreme speeds will prevent growth, so we learned about the need for an ideal current.

Results of seaweed growth stimulation using CO2 and current control

CO2 and an ideal water current are required to accelerate the growth of seaweed. In order to manage these 2 factors rationally, Professor Senaha proceeded by introducing IoT and AI into his seaweed cultivation demonstration project.

Introducing IoT & AI to Achieve Efficient Cultivation

For our projects, we are using high speed cameras to observe the flow of water inside the ocean. We look at which direction the water is flowing in, and how it is being pushed by the wind. I already have the knowledge and technology to measure these factors from my previous work in thermal engineering.
Observing these flows shows us the speed of the current around the seaweed, and the degree of disturbance. If the water is moving too fast, the seaweed will stop growing well. Likewise, if the disturbance is too strong, then the surface of the seaweed will be hit by vortexes. The seaweed will redirect the energy gained from photosynthesis to protect itself and growth will be slowed. It’s important to provide the proper current for seaweed. In order to quantify that ideal state, we introduced equipment to measure the degree of active photosynthesis.
All future tests will collect data that shows exactly how much photosynthesis is happening as we adjust the flow of seawater, which indicates the seaweed’s degree of growth. Our goal now is to use that data together with IoT and AI to create a cultivation system that can provide the perfect conditions for seaweed.

When it comes to seaweed cultivation, we have the technology, but without IoT and AI in place, it means that people have to start preparation early each day and keep working long after the sun goes down. The labor situation goes from bad to worse.
But with better mechanization, the machines will keep running while the staff is in bed, and you can significantly reduce the labor load. It’s a fact that primary sector industries in Okinawa are also have trouble attracting enough workers. Lower birth rates means fewer workers. I think that the introduction of IoT and AI will compensate for these issues.

If introducing IoT and AI can help advance seaweed cultivation in the near future, we can hope for revitalization in primary sector industries like fishing and aquaculture. In addition, if seaweed can be used for biofuel, then it will also become possible to make even greater contributions to a recycling society. Expectations are high for new developments in this industry.

Sea grapes (umibudo) in cultivation tanks

Interview Date: December 18, 2018



Creating Systems to Capture & Utilize CO2 Effectively is Important

Innovation in Seaweed Cultivation to Build a Recycling Society

Introducing IoT & AI to Provide Ideal Conditions for Seaweed Cultivation

Keep Trying New Things to Discover the “Right” Project

Izuru Senaha

Born 1967 in Okinawa. Graduated 1991 from the University of the Ryukyus, Faculty of Engineering, Energy and Mechanical Engineering Department. Continued at the University of the Ryukyus as an assistant after completing his MS Mechanical Engineering in 1993. Awarded PhD Engineering from Nagoya University Graduate School of Engineering in 2001. Returned to the University of the Ryukyus as an associate professor of Engineering in 2006, and accepted a position as full-time professor in 2018. Began research on CO2 reduction and utilization using marine biomass in 2009. His current research project is investigating the early development of seaweeds like sea grapes (umibudo) and Nemacystus decipiens (mozuku) through cooperation with a diverse spectrum of other research institutes to contribute to fields of industry in Okinawa.

Awards & Honors (Selected)
・2009 Contribution to Society Award
・2010 Faculty of Engineering Contributor Award
・2010 IMPRES 2010 Best Poster Award
・2013 Rocky Challenge Award

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