As an important technology for global warming countermeasures, research and development for directly recovering carbon dioxide from the atmosphere is becoming active, and in Japan, as a large-scale project, full-scale research will start from this year, and new substances and new substances Development of a special membrane is underway.

The United Nations expert agency, IPCC = Intergovernmental Panel on Climate Change, said that when global average temperatures rise twice compared to the second half of the 19th century, many will be seriously affected by extreme heat waves and daily water scarcity. Predicting that it will be affected, the importance of limiting the rise to 1.5 degrees is becoming widely recognized.

For this reason, it is necessary to reduce the emission of carbon dioxide, which is a greenhouse gas, to virtually zero by around 2050, and as an important technology for realization, a method of directly recovering carbon dioxide from the atmosphere. Development has begun worldwide, and a large-scale project with an investment of 5.5 billion yen has been launched in Japan over three years, and full-scale research has begun this year.

Nagoya University and a gas company are jointly working on the development of a unique method that combines a special substance that absorbs carbon dioxide and cold energy called "cold heat" of liquefied natural gas, which has been almost discarded until now. In addition, Kyushu University is conducting research with a unique idea of ​​selectively extracting carbon dioxide with an extremely thin film.

In both cases, the challenge is to further improve the efficiency of carbon dioxide recovery so that more carbon dioxide can be recovered than the carbon dioxide produced during the manufacturing and operation of the entire system.

Kenji Yamaji, Vice President of the Research Institute of Innovative Technology for the Global Environment, who is the organizer of the project, said, "It can be said that it is the last trump card for global warming countermeasures. It must not be. "

"Recovery" from the atmosphere is the "last trump card"

According to a report compiled three years ago (2018) by IPCC = "Intergovernmental Panel on Climate Change", a UN specialized agency created by scientists in the fields of meteorology and the environment, the average global temperature is in the latter half of the 19th century. If the temperature rises by 2 degrees Celsius, the temperature will rise to 1.5 degrees Celsius due to the effects of more extreme heat waves and heavy rainfall, as well as a larger rate of decrease in food production such as corn and rice. The importance of things is becoming widely recognized.

The IPCC report states that the average global temperature is already about 1 degree higher than in the latter half of the 19th century, and simulations predict that the temperature will rise by 2 degrees and 1.5 degrees. I will.

As a result, a two-degree rise will increase the number of people frequently exposed to extreme heat waves by about 400 million, and heavy rains will increase in frequency and intensity worldwide, compared to a 1.5-degree rise. In addition, it is predicted that the number of people whose lives will be threatened by severe water shortages may increase by about 90 million people worldwide.

In terms of food, it is said that the rate of decrease in grain production such as corn and rice is increasing in Africa and Southeast Asia, and the nutritional quality of rice and wheat is declining.

For these reasons, the importance of keeping the temperature rise at 1.5 degrees Celsius is widely recognized.

To stay at 1.5 degrees Celsius, it is said that carbon dioxide emissions, the most influential greenhouse gas, will need to be virtually zero by around 2050.

In Japan, in October last year, Prime Minister Suga declared that he would aim to realize a carbon-free society by reducing greenhouse gas emissions to zero by 2050.

Until now, the development of technology to reduce carbon dioxide from the exhaust gas from factories has been continued, and it has been confirmed that the thermal power plant in Omuta City, Fukuoka Prefecture can recover more than half of the emissions in the demonstration project.

However, in order to reduce carbon dioxide emissions to zero by around 2050, it has been pointed out that there is a need for a method of recovering carbon dioxide from the atmosphere as well as reducing emissions.

For these reasons, technological development for artificially recovering carbon dioxide in the atmosphere is accelerating.

Kenji Yamaji, Vice President of the Research Institute of Innovative Technology for the Global Environment, who is familiar with global warming countermeasure technology, said, "Zero carbon dioxide emissions in a number of industries that we must have, such as aircraft, ships, and the steel industry. It is difficult, and we need to think of ways to reduce the amount of emissions to zero by recovering from the atmosphere. This technology can be said to be the last key to combating global warming. "

Full-scale research will begin this year in Japan

The development of technology to recover carbon dioxide from the atmosphere tackles challenging issues, and research has begun in earnest this year in a large-scale national project called the "Moonshot R & D System."

The project aims to establish prototype-level technology that will pave the way for practical use by 2030, and to disseminate it to society by 2050.

Research and development is also being carried out overseas, and in Switzerland, a large blower blows air into the device to allow chemical substances to absorb carbon dioxide in the atmosphere, and then uses the heat generated from the waste treatment facility to produce carbon dioxide. A plant has been set up to demonstrate the recovery of carbon dioxide.

Operation is planned in Iceland in a similar way using geothermal heat.

However, it is necessary to improve efficiency so that more carbon dioxide can be recovered than carbon dioxide produced in the process from manufacturing to operation of the entire system, and cost is also an issue.

Hiroyuki Yamada, General Manager of the New Energy and Industrial Technology Development Organization, NEDO, who is in charge of the operation of this business, said, "We are working on a very challenging and difficult place, but we will identify the technology in order to connect it to social implementation. I would like to support research and development by firmly evaluating the progress and progress. "

Utilizing the abandoned "cold heat"

Research groups such as Toho Gas, a gas company headquartered in Nagoya, and Nagoya University are working on the development of a unique method for recovering carbon dioxide using previously discarded energy.

Liquefied natural gas is used so that Japan accounts for 20% of the world's imports, but when it is imported using a dedicated ship, it is cooled to minus 162 degrees Celsius, and the cold energy called "cold heat" is gas. Most are thrown away when used as.

The research group combined "cold heat" with a solution of a special substance that absorbs carbon dioxide.

After absorbing carbon dioxide in the atmosphere with a special solution, it can be recovered as dry ice by cooling it with "cold heat".

We currently engaged in the development of new materials so that the further rises efficiency to recover the carbon dioxide at the level of the laboratory, we plan to build a demonstration plant to the prospect of the 10 years.

Professor Yukinaga Norinaga of Nagoya University says, "The principle is quite clear, and I would like to proceed with research and development so that we can develop technology that reduces CO2 as a whole."

In addition, Yoshito Umeda, Toho Gas's advanced technology advisor, said, "Cold heat that is not being used effectively is a waste, and global warming has become a serious problem, so I would like to contribute with this technology."

"Recovery" using "membrane"

Professor Shigenori Fujikawa of the Kyushu University Negative Emission Technology Research Center is working on development with a unique idea of ​​recovering carbon dioxide from the atmosphere using an extremely thin film.

So far, we have created an extremely thin film of 34 nanometers, which is about one-300th the thickness of food wrap.

This membrane has small gaps through which carbon dioxide molecules can pass, allowing carbon dioxide to be recovered.

By changing the chemical properties of the membrane, we will improve it so that carbon dioxide molecules can pass through more selectively, and within a few years we would like to develop a small prototype that can be used at home and at work.

Professor Fujikawa says, "I don't think there is any other method in the world that uses membranes. There are many challenges, but I want to do my best."