Next-Gen Biofuel: High School Students Explore Mazda and Hiroshima University’s Joint Microalgae Project

It all began with an email: “We would love to visit Mazda’s research facilities and plant, to gain hands-on knowledge and experiences that go beyond what we learn in class. Would it be possible to arrange a tour?”

 

The sender of the email was Runa Irie, a student at Hiroshima‘s AICJ High School, who became interested in Mazda’s environmental initiatives after hearing about them when attending Sustainable Brands Tokyo in February 2024.

 

Irie and her classmates were particularly interested in Mazda’s research into biofuel, a joint project that was launched a few years ago. The project is exploring the potential of microalgae, found in rivers and seas, as a next-generation clean energy source.

 

With a growing concern about the climate crisis and an interest in alternative energy, Irie was keen to learn about the current advancements in biofuel and gain a deeper knowledge of sustainable energy.

 

Inspired by the students’ enthusiasm, we invited Irie and three of her classmates to take a tour of our facilities, and share some of the exciting developments in sustainability at Mazda. Yutaka Kawasaki, from the Corporate Strategy Division, led the two-day tour of Mazda’s plants and research facilities.

 

In the first part of this series, we follow the students as they learn about developments in microalgae biofuel, beginning with a visit to the research laboratory at Hiroshima University, and followed by a trip to the cultivation facility onsite at the Hiroshima Plant.

Redefining Approaches to CO2 Reduction: How microalgae biofuel joint research with Hiroshima University could achieve carbon neutrality

Since 2010, Mazda has been working on developing a next-generation clean fuel for diesel engines. Research has been focused on a project which converts Nannochloropsis—a genus of microscopic algae found in rivers and lakes—into a biofuel. In April 2017, Mazda teamed up with Hiroshima University, establishing a joint research course in next-generation automotive technology and a research lab focused on algae-based energy. At the same time, Mazda began experiments with mass-production of algae at our plant. On the racetrack, Mazda has been trialing biofuel since 2021.

Producing biofuel with Nannochloropsis.

Mazda’s goal isn’t simply powering cars with fuel derived from Nannochloropsis: we are determined to establish this fuel as a viable alternative to gasoline and petroleum, while also reducing our CO₂ emissions and achieving carbon neutrality. That’s why we’re working with our partners to make carbon-neutral fuel a practical option.

Nannochloropsis can produce a large amount of lipids—naturally occurring oils—making it ideal for biofuel production. The joint research project between Mazda and Hiroshima University aims to mass-produce a Nannochloropsis with a high-lipid content. These lipids can then be processed and converted to biodiesel.

Irie explains what drew her to this project. “I’ve been interested in environmental issues ever since junior high, and have been to several lectures on the topic. I always try to be mindful of my energy use, and reduce where I can, but I often wonder how much of a difference my individual actions make to reducing CO₂.”

Irie continues, “I soon realized that the only way to stop global warming was to change the source of the energy we’re using to a cleaner alternative. When I heard of Mazda’s research into microalgae as a biofuel, I just had to learn more, and sent out an email straight away. It’s the kind of next-generation development that we can’t learn about at school, so I knew I had to go straight to the source at Mazda.”

Runa Irie (center) pictured with classmates from Hiroshima’s AICJ High School. Yutaka Kawasaki (Carbon Neutral & Resource Circulation Strategy Department, Corporate Strategy Division), who the students met at Sustainable Brands Tokyo, greets the group at the Mazda Head Office in Hiroshima to begin the tour.

Students head to the first stop on the tour in Mazda’s CX-60 Biofuel. The car is powered by a fuel combination of 80% petroleum-derived diesel fuel and 20% next-generation biodiesel fuel.


Cultivating Innovation with Industry-Academia Collaborations: Using Hiroshima University's advanced genome-editing technology to engineering microalgae for biofuel production

The tour began at Hiroshima University, in the joint research lab for algae-based energy. Here, Hiroshima University’s researchers are using genome-editing technology to alter the DNA of Nannochloropsis and make it more effective for biofuel production. Assistant Professor Kumiko Okazaki from the Collaborative Research Laboratory at Hiroshima University's Graduate School of Integrated Sciences for Life talks the students through the research.

“Nannochloropsis can store up to 50-60% lipids in its cells, making it the most suitable algae for biofuel production,” explains Professor Okazaki. “In our lab, we’re altering the DNA of Nannochloropsis to improve its lipid productivity, while also investigating the best conditions to efficiently cultivate this resource.”

Working together with Shinichiro Maeda and those engaged in biofuel development at Mazda’s Advanced Environmental Technology Research Field, this industry-academia collaborative team’s research has gone through numerous trials and iterations.

Maeda explains, “Microalgae biofuel has many advantages as a clean energy. Its emissions have a very low environmental impact, and it’s a renewable resource that can be continually cultivated. If we could substitute even a small portion of current fossil fuels with this clean energy, we could make a considerable impact on the environment.”

Assistant Professor Okazaki (center) and Mazda’s Shinichiro Maeda (right) continue research as part of the collaborative partnership that began in 2017, bringing together industry and academia with strong ties to Hiroshima.

Like plants, Nannochloropsis is a photosynthesizing organism. It absorbs CO₂ and uses light energy to produce lipids that can be converted into biofuel.


The Biofuel Process: Oil extracted from microalgae (right) undergoes hydrogenation and other processing treatments to produce a liquid that can be used as fuel (left). The processed fuel can now be used as a diesel biofuel to power vehicles. Mazda is also exploring ways to use byproducts from the process, repurposed as materials for car production, or as a health food ingredient that takes advantage of algae’s nutritional value.


This device accelerates photosynthesis in microalgae. Here, a culture of microalgae, seawater, and nutrients (nitrogen, phosphorus, potassium) is exposed to an intense light source while CO₂-enriched air is circulated and stirred through the mixture, facilitating carbon dioxide absorption from the air.


The Japanese government aims for Japan to be carbon neutral by 2050, and industry has a big role to play in achieving this goal. As a manufacturer of cars, a technology that has a considerable impact on the environment, Mazda has been strengthening initiatives to reduce CO2 emissions by taking a variety of approaches. Maeda shares how the microalgae biofuel joint research project, an example of how we’re contributing to carbon neutrality at Mazda, came about. 

“We wanted to take an approach that could reduce emissions and build on the advances we’ve made with our internal combustion engine,” explains Maeda. “This led us to focus on improving engine performance in hybrid vehicles, while also looking for a carbon-neutral fuel alternative. As we explored various biofuel options, we began to see the potential of microalgae, but we knew that for it to be a viable, practical alternative, we’d need to enhance its performance and productivity. 

“That’s when we turned to Hiroshima University. Their genome-editing expertise and technology was what we needed to cultivate a modified Nannochloropsis that could be used as a biofuel.”

Professor Okazaki describes the project’s importance. “This project offers a huge opportunity not just for Hiroshima University, but for me personally. My research into algae began before this project, but thanks to this industry collaboration, I have access to better resources and can progress the research at a quicker pace. More than that, this project is a way for the university to use its research to help society in a valuable and meaningful way.”

Lipids in cultured Nannochloropsis are dyed with a fluorescent reagent and observed through a fluorescence microscope, to visualize the buildup of fats in the cell.


The students share their excitement as they see the lipids light-up in the microscope.


Viewing the lipids in the Nannochloropsis gave the students a better understanding of how microalgae could be used for biofuel, but it also raised questions.

 

“It was amazing to see the amount of lipids produced by just one cell,” enthuses Irie. “Still, microalgae are literally micro in size—you’d need a huge amount of Nannochloropsis to start biofuel production. Is that even possible?”

Scaling Up Microscopic Potential: The realities of mass-producing microalgae for practical applications

Helmets on, the four students head to the microalgae cultivation facility.

Irie raised a valid point: Can we realistically produce enough microalgae to power a car? To answer this question, Kawasaki took the four students to Mazda’s microalgae cultivation facility, onsite at the Hiroshima Plant. This facility tests microalgae cultivation under different conditions to the lab. Once cultivation can be successfully stabilized, the next stage is testing how it converts into biofuel.

Two types of tanks have been set up next to the power plant at the Hiroshima Plant. The tanks are about 100 times larger than those at Hiroshima University, and enable testing of microalgae cultivation outside of lab conditions.

“Are you producing two different types of algae in the tanks?” asks Irie. “How much does each tank produce?” asks another student. The visit to the tanks ends up prompting more questions than answers in the young researchers.


Maeda describes the tanks function to the students.

“We’re using two tanks to experiment with cultivating different algae species under identical conditions,” answers Maeda. “We have Nannochloropsis in one tank, and a microalgae species collected right here at the plant in another. The Nannochloropsis tank is filled with seawater, and the other with freshwater. As we consider implementing mass-production, we need to think of various eventualities, such as how to produce the biofuel when seawater is not available. That’s why we’re also researching algae cultivation in freshwater, to give us more options for practical applications.”

Maeda continues. “As for how much we can produce, in a tank this size and with favorable conditions, we can produce one million Nannochloropsis per liter, over a two to three day period. From two weeks cultivation in a 1,000 liter tank, we can harvest around 400 grams of lipids.

“This facility lets us produce more algae than the Hiroshima University lab, but the Nannochloropsis in the lab have a better lipid-productivity performance. Right now, we’re testing different cultivating environments and conditions to find one that can consistently produce high-performing microalgae.”

Freshwater cultivation of microalgae uses wastewater from the plant. “Safely treating wastewater before disposing into the sea requires a lot of money and energy,” says Maeda. “If we could use this wastewater to produce fuel, we’d be killing two birds with one stone.”



Unlike the lab where light and temperature can be controlled, cultivation in this outdoor environment has to contend with seasonal changes and fluctuating temperatures, adding another hurdle to stable production. There is also a difference in the productivity of each cell between the lab and the plant facility. How to produce on a larger scale without impacting productivity is the current challenge.



Increases in microalgae are measured using a turbidimeter. Maeda and his team compare the doubling time under various conditions and analyze the result as they work towards stable cultivation.



“Even if we can establish the technology,” adds Maeda, “bringing it to market is another issue. Right now, we’re facing each hurdle as it comes. But I believe in this project, and believe that we can find a feasible, real-world product. That’s what keeps driving me forward.” 

For Maeda, it’s not just about a successful project. It’s also about his personal ambition to create a sustainable vehicle.

“I began at Mazda as an engineer for rotary engines. I’ve loved sports cars ever since I was a boy, and being able to be a part of that world was like a dream come true. But I’ve always been concerned about the environmental damage caused by CO2 emissions.

“If we can create a biofuel with practical applications, then I and everyone can experience the joy of driving without worrying about the environmental cost. I want to be a part of making that future a reality. My involvement in this research project lets me contribute to advancing car culture to the next stage.”


Once dried, the algae cultivated at Mazda could be used as biochar to generate power onsite.

The Long Road to Practical Applications: Staying positive about the real-world potential of algae biofuel

After visiting the Hiroshima University lab, and observing the experiments with mass-production at the Hiroshima Plant, Irie shared her impression of environmental efforts at Mazda.

“If I’m being honest,  I think the technology is a long way from being at the stage where it can be used in the real world. But, seeing this research firsthand was an incredible experience for me. When microalgae-fueled cars finally come to market, I’ll be lining up to drive one.

 

“Energy is an area that I’ve always been interested in and I hope to one day pursue research in this field. Today’s tour was a timely reminder of how much I still have to learn, and has inspired me to learn even more about microalgae, and the whole field of bioenergy.”


Irie’s honest yet hopeful take on the research struck a chord with Mazda employees, Maeda and Kawasaki.

Kawasaki closed this part of the tour with these words. “At Mazda, we’re committed to reducing CO₂ emissions by any means within our power—which is why we’re researching biofuels and microalgae. But we can’t do it alone. To achieve carbon neutrality, we need to work together, pool our expertise, and get everyone onboard to approach the problem from all angles.

“That’s where you come in. Young people like you are indispensable to making this dream a reality. I’m looking forward to seeing what you four achieve in the future, as we all work on bringing the carbon neutral dream to fruition by 2050.”

Kawasaki shares his inspiring ambitions for the future, and Mazda’s commitment to carbon neutrality. 




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Redefining Approaches to CO₂ Reduction:Could minuscule algae achieve carbon neutrality? 

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