Hitachi Zosen takes on the challenge of zero carbon with a "dehydrator"

The 26th Conference of the Parties to the United Nations Framework Convention on Climate Change (COP26), which ended on the 13th, included an agreement aimed at phasing out coal-fired power generation. As governments and private sectors around the world focus their efforts on reducing carbon dioxide (CO2) emissions, Hitachi Zosen is working on the practical application of a technology called "methanation," which produces city gas from CO2. Applying the technology of "dehydrator", which is our specialty, we will challenge carbon zero.

Using Surplus Electricity as Gas Resources

Hitachi Zosen's Chikko Plant faces Osaka Bay. In early November, the PtG Square, a plaza that aims to utilize CO2, appeared. PtG stands for "Power to Gas". It is difficult to adjust the amount of power generated by renewable energy sources such as solar power, and sometimes we end up with surplus power. The idea is to turn it into something that can be used as a gas resource.

Here, Hitachi Zosen is working on the practical application of a technology called "methanation," which reacts CO2 and hydrogen with a catalyst to produce methane. We gathered equipment and people from within the group so that we could observe everything from basic research to equipment here.

For methanation, the company's method is divided into two stages. First, hydrogen is produced from surplus electricity, etc., and then methane is produced from the produced hydrogen and CO2. Methane can be used as city gas.

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Secret of high efficiency of "99.6%"

The company's long-lived technology is utilized. The electrolyzer, which produces hydrogen from electricity, can be operated for one hour, producing enough hydrogen to fill up three Toyota Mirai fuel cell vehicles that run on hydrogen. We applied the technology cultivated by Hitachi Zosen as an industrial dehydrator manufacturer.

Next is the process of producing methane. Behind the plaza, a three-story steel-framed device rises. Two long, narrow cylinders filled with catalyst pierce the floor. When air mixed with CO2 and hydrogen circulates in two cylinders, methane can be extracted with a high efficiency of 99.6%.

The higher the efficiency, the less hydrogen is wasted in obtaining methane, but methanation efficiency is generally considered to be 70-80%. Why is it possible to produce such a high figure of 99.6%? The secret lies in the "catalyst" that Hitachi Zosen has spent a long time improving.

"For more everyday use"

About 30 years ago, in 1993. "Would you like to propose 'Methanation'?" Professor Emeritus Koji Hashimoto of Tohoku University approached a researcher at Hitachi Zosen. The company has long been engaged in the development of environment-related equipment such as waste incineration technology. At that time, a researcher came to Tohoku University to study materials with the aim of commercializing a device that produces hydrogen from seawater.

Mr. Koichi Izumiya, the current technology development group leader, was also one of the researchers at Tohoku University at the time. "Conventional 'methanation' mainly used ruthenium, a precious metal. It was rare, and we had to put a lot of pressure on it, so we had to make it something that could be used on a daily basis," he recalls.

In 1995, we developed a basic catalyst. After that, we continued to make small improvements and finally achieved a high efficiency of 99.6%. Furthermore, there is an advantage that the device can be made smaller because it does not need to apply high pressure. It has been exhibited at the Davos conference in 2018. Mr. Izumiya says, "There is a sense that there is a rapid increase in interest" in response to the recent decarbonization trend, such as the decision to use it for a demonstration experiment by Tokyo Gas.

Challenges for commercialization still remain

However, there are still challenges to commercialization. One issue is the cost of hydrogen. The cost of the current equipment is 200,000 yen per day to produce hydrogen, which is the raw material for methane, from surplus electricity.

Executive Officer Toshihiko Yasuda, who is the head of the PtG Business Promotion Office, draws up a business concept, saying, "We aim to be a receiver for companies that have no choice but to emit CO2" (Mr. Yasuda). Materials businesses such as steelmaking and cement inevitably emit CO2 in the production process. The idea is to solve that problem.

Some of our customers have factories that generate hydrogen on their premises. In that case, there are cases where you don't have to worry about the problem of procuring hydrogen. In 2030, the company aims to achieve 10 billion yen in methanation-related sales.

Hitachi Zosen's method of methanation is based on the Nobel Prize-winning technique that French chemist Paul Sabatier published in the early 20th century. He aims to contribute to a decarbonized society by accumulating the know-how of industrial dewatering machines and environmental equipment that he has independently cultivated.