From Chisato Horiuchi in Tokyo, Japan
Artificial photosynthesis, Toyota and Nippon Steel also participated. Green hydrogen cheap supply
Artificial photosynthesis waiting for flowering ㊤
Attention is being paid to "artificial photosynthesis," which produces useful substances from sunlight, water, and carbon dioxide (CO2). In the middle stage of hydrogen production, a large-scale demonstration with the participation of Toyota Motor Corporation and Nippon Steel will begin in 2030, aiming to produce "green hydrogen" that does not emit CO2 at the time of production at a lower price than the method derived from natural gas. We will examine front-line efforts and issues toward the realization of "dream technology," which is the trump card for decarbonization.
Further large-scale demonstration to reduce costs begins (a facility in Ibaraki Prefecture that succeeded in demonstrating about 100 square meters last year)
"Toyota's exhaust gas catalyst-related technology is indispensable for the development of photocatalysts and the cost reduction of equipment. We welcome your participation." Toru Setoyama, Executive Fellow of Mitsubishi Chemical, said: The company has been working with the University of Tokyo and others for the past 10 years on an artificial photosynthesis demonstration project. With the addition of Toyota and others, a new project with an eye on practical application will begin.
■ Support of 30 billion yen
The new project first develops a photocatalyst sheet that decomposes water into hydrogen and oxygen. Water is trapped in the panel to which the sheet is attached, and sunlight is applied to produce hydrogen. The panel has expanded from the predecessor demonstration project to a few to 100 hectares. The production cost of hydrogen is planned to be reduced to 240 yen per kilogram in 30 years, which is equal to or less than that of hydrogen separated from natural gas, and to 170 yen or less in 1950. The New Energy and Industrial Technology Development Organization (NEDO) has decided to provide 30 billion yen over the next 10 years.
If hydrogen can be produced cheaply, Toyota can use it to power fuel cell vehicles, and there is a possibility that cars can be produced cheaply from plastic parts made from hydrogen. Since it is green hydrogen that does not emit CO2, if this hydrogen is used, it will lead to the suppression of CO2 emitted during the manufacture of cars.
Nippon Steel, which is working on "hydrogen ironmaking" that uses hydrogen instead of coal to reduce iron ore and drastically reduces CO2 emissions, also needs cheap hydrogen. Nippon Steel says, "We want to build a supply system for green hydrogen."
The participation of Toyota and Nippon Steel, which represent Japanese industry, is a sign of high expectations for artificial photosynthesis, while there is no waiting for a response to decarbonization.
Artificial photosynthesis uses sunlight to decompose water into hydrogen and oxygen, and the produced hydrogen and CO2 produce organic matter. Literally, it artificially performs the function of photosynthesis in plants. The mainstream of decomposition is a photocatalyst that absorbs sunlight or two methods that use electrodes. CO2 is collected from factories and reacted with hydrogen to make plastic raw materials. Hydrogen and oxygen generated on the way are also used for other purposes.
■ Conversion efficiency to 10%
For industrial use, it is indispensable to produce hydrogen as cheaply as possible by increasing the scale. In this regard, the predecessor demonstration project by Mitsubishi Chemical and others succeeded in producing hydrogen in the world's largest panel of about 100 square meters using a photocatalytic method in 2009, and achieved great results. The energy conversion efficiency is about 1%, which is far from the standard of 5 to 10% for practical use, but we aim to achieve 10% in a new project that will be taken over by increasing the scale.
In addition to this project, there are a series of attempts in Japan with an eye on practical application.
Professor Yutaka Amao and his colleagues at Osaka City University, in collaboration with Iida Group Holdings, have developed a method for producing formic acid from sunlight, CO2, and water, and then decomposing formic acid with a catalyst to produce hydrogen. The water produced by burning hydrogen reacts with CO2 to produce formic acid again. An "artificial photosynthesis house" that supplies electricity and hot water through this circulation was completed on Miyakojima, Okinawa Prefecture. Demonstration will begin within 22 years. "There was a way to cover all the energy of one house with artificial photosynthesis" (Professor Amao)
Toyota Central R & D Labs. (Nagakute City, Aichi Prefecture), a research and development company of the Toyota Group, has also developed a device that produces formic acid from solar cells, water, and CO2. By using electrodes connected to solar cells, a conversion efficiency of over 10% was achieved with a 1-meter square device in December last year. This size is the highest level in the world. In the automobile industry, Nissan Motor Co., Ltd. is also conducting research on making raw materials for car parts by artificial photosynthesis in collaboration with Tokyo Institute of Technology.
■ Cost issues
Although the path to practical use has become clear, there are still issues in terms of cost. Even if hydrogen can be produced cheaply, if a highly efficient catalyst that reacts with CO2 cannot be developed in the subsequent process, the yield will decrease and the plastic raw material to be produced will increase. To compete with petroleum-derived plastics at a price, it is also necessary to procure CO2 cheaply.
Tomohiko Sato, a senior researcher at Mitsubishi Research Institute, explains, "We should draw pictures with an eye on the international supply chain." In order to make effective use of sunlight, it is better to set up a large plant in the area near the equator. If a liquid raw material can be produced by artificial photosynthesis, it will be easier to transport than hydrogen. "If you make it in the Middle East or Australia and transport it to Japan, you have the advantage of being able to use your existing industrial infrastructure without waste," he said.
Artificial photosynthesis was a hot alternative to fossil fuels before and after the 1970s oil crisis, but after the oil crisis it went down in Europe and the United States. After that, around 2010, attention was regained in Europe and the United States, and "the Paris Agreement of 15 years, which was an international agreement to reduce greenhouse gases, boosted the momentum of propulsion at a stretch" (Senior Fellow Takeshi Morikawa of Toyota Central R & D Labs.). Overcoming challenges such as cost reduction still requires time and funding to support R & D. The focus is on whether it can be put to practical use while receiving the great tailwind of decarbonization.
■ The number of patents is leading China, Japan leading, the status declines
Japan's position is declining due to research and development of artificial photosynthesis. According to a survey conducted by the Mitsui & Co., Ltd. Strategic Research Institute using data from patent sites of German information services, the number of valid patents related to Japan (including pending patents) was less than half that of China as of January 2010. China has also improved the quality of patents in recent years. Japan is said to have led the world so far, but the situation is far from safe.
The number of valid patents in China increased to 562 as of January, a 10-fold increase in the last 10 years, surpassing Japan in 2016 and the United States in 2018. Many Chinese patent applications are for the domestic market, and many are said to have low value. However, recently, there are an increasing number of notable international patents, such as methods for making raw materials such as chemicals and pesticides from CO2 and hydrogen. Ryusuke Ishiguro of the Mitsui & Co., Ltd. Strategic Research Institute said, "In the future, we will improve the quality and increase the number of international applications."
China is making great strides in basic research, which has been followed by many other countries. In September 2009, a Chinese research institute published the results of artificially synthesizing starch in the US Science magazine. It is said to be the most difficult to imitate in plant photosynthesis, but it has become a member of the world's most advanced group by analyzing and reproducing complex reactions in detail.
The number of valid patents in Japan also increased 3.8 times in 10 years to 269, but the momentum is inferior to that of China, and the number of patents is competing with the United States of 213. Although there are companies such as Fujifilm and Toyota Central R & D Labs that boast one of the highest number of patent applications in the world, they have not been able to counter the physical offensive in China.
For Japan, where resources are scarce, artificial photosynthesis that creates resources is a dream technology. In fact, Professor Akira Fujishima of Tokyo University of Science, who discovered the "Honda-Fujishima effect" in which a photocatalyst decomposes water into oxygen and hydrogen, and Jian-Ren Shen of Okayama University, who elucidated the crystal structure of proteins essential for photosynthesis in plants. Many researchers, such as professors, have announced important achievements called "Nobel Prize candidates". There is also a view that even if research declined in Europe and the United States after the oil crisis, research continued in Japan, creating a technological advantage after that.
It was the established theory that such accumulation kept high competitiveness, but if you look at the number of patents objectively, it seems to be a story of the past. It is said that the number of European countries such as Germany applying for high-value patents is increasing due to the trend of decarbonization. There is a risk that Japan's status will decline further in the future.
Yuki Misumi and Yoshio Nagata will be in charge.
