ENTERPRISE FUTURE
Osaka Gas Tackles Air Pollution in Jakarta with Its Innovative Air Purification Technology

Osaka Gas's ACFs have excellent NOx removal capability.

What are ACFs anyway?
What are ACFs anyway?
ACF stands for activated carbon fibers. ACFs are highly porous and manufactured from carbon fibers, a material known for being lightweight and strong. Unlike granular activated carbon, ACFs have tiny pores of 1–2 nm in diameter called micropores uniformly distributed in the surface of fine carbon fibers of 10–20 μm in diameter. These micropores enable ACFs to adsorb toxic substances to remove them from the air at a speed at least ten times higher than that of granular activated carbon. This is a considerable advantage of ACFs. As a familiar example, ACFs are used in cartridges for household water purifiers.
What made Osaka Gas decide to use this kind of material?
What made Osaka Gas decide to use this kind of material?
Osaka Gas used to produce city gas from coal, and this process produced liquid coal tar and other coal-derived by-products. Having worked on research and development to find an effective use of the liquid coal tar, Osaka Gas ended up creating a technology of solidifying it to produce ACFs.
What inspired Osaka Gas to utilize ACFs for air purification?
What inspired Osaka Gas to utilize ACFs for air purification? A university study showed that Osaka Gas's ACFs have excellent nitrogen oxide (NOx) removal capability. ACFs inherently oxidize NOx to convert it into nitrate ions and desorb them as clean air. ACFs come in various types, which differ in raw materials. Other manufacturers produce and sell other types of ACFs. The study data revealed that Osaka Gas's ACFs have a greater oxidative effect than competitors'.
That was fortunate.
Haha, yes. It was also found that ACFs that have adsorbed NOx recover their adsorption capacity after being washed with water. Moreover, researchers at the university guaranteed that Osaka Gas's ACFs are highly durable.
Is that why Osaka Gas decided to use the material for air purification?
A wide variety of roadside exhaust gas removal systems have been developed and tested for quite some time. However, they tended to be very bulky, and their poor cost-effectiveness prevented them from becoming popular. In contrast, ACFs were considered by the Japanese Ministry of Land, Infrastructure, Transport and Tourism to be a promising material for a system that would work without electricity, require little maintenance, and achieve a long life. Accepting an order from the ministry, we proceeded with the development of the system to be put to practical use.

Prompt development enabled the system to be completed in about half a year.

Test unit on his right

Test unit on his right

And then you have completed the ACF units.
That's right. When the development project started, a schedule for system installation on a national road had already been arranged. So we came under pressure to complete the system within half a year or so. We decided to make it a unit system for easy installation on the site, but we had trouble figuring out how to make air flow smoothly through the units.
Internal structure of the ACF unit

Internal structure of the ACF unit

To let air flow?
Natural wind and the wind turbulence generated by running vehicles ventilates air into the units because they are not powered by electricity. We need to make sure that air touches the ACF felts inside the units well while passing through them. We came up with an idea to adopt a corrugated inner structure like cardboard. After making dozens of prototypes and conducting wind tunnel tests, we finally succeeded in producing a parallel flow from the front to the rear of the units by arranging ACF felts and porous separators alternately.
The ACF units were completed and installed. How did it go?
The ACF units were completed and installed. How did it go?
NOx measurement data suggest that the units reduce NOx equal to that discharged from approximately two thousand trucks passing by the road per day. You can safely say that our ACF units have proved very effective for air purification.

The project for NOx reduction started in Indonesia.

ACF units installed for the pilot project Photo with Indonesian government officials and JICA staff members

ACF units installed for the pilot project

Photo with Indonesian government officials and JICA staff members

I heard that Osaka Gas then looked outside Japan.
The Japanese market was shrinking with less traffic congestion in an improved road environment and the spread of EVs and other low-emission vehicles. We considered making use of our ACF units in developing Asian countries, where the issue of air pollution stubbornly persisted. That is why we applied for a Collaboration Program with the Private Sector for Disseminating Japanese Technologies for the Social and Economic Development of Developing Countries, which was being publicly offered by the Japan International Cooperation Agency (JICA).
What exactly is the program?
Officially called the Project for Activated Carbon Fibers (ACF) Air Purification Unit in the Republic of Indonesia, the program is targeted at Indonesia. In Jakarta's urban areas, severe traffic congestion has caused a very high concentration of NOx, an air pollutant, and the incidence rate of young adult asthma patients is several times higher than in Japan. We decided to begin with a pilot project with the help of the JICA in September 2018 of installing ACF units along a highway in Jakarta and measuring their effectiveness in reducing NOx concentration in the air. If pilot test data proves the units' effectiveness in NOx reduction, we would like to move on to a full-fledged project for installing ACF units to reduce the pollutant.
When will the pilot project be completed?
It is scheduled to be completed in September 2019, and then we will verify the effect of the units. ACF units are budget-friendly as well as eco-friendly. They require initial costs but almost no running costs. We would definitely like to achieve good results that will lead to our next move. We are hoping to contribute to the reduction of air pollution and health damage in Indonesia.
What other possibilities do you see for ACF?
What other possibilities do you see for ACF?
ACF has a sound absorbing capacity equal to glass wool, a material known for its excellent sound-absorbing quality. We have developed sound insulating panels that combine two functions: air purification and sound insulation. We are expecting a future increase in demand for the panels.
You must be excited to see how it will turn out.
Well, for the time being, we are devoting ourselves to a large-scale installation of ACF units in Indonesia toward their widespread use. If this goes well, Osaka Gas's air purification technology will receive increased recognition, and I will feel my work has paid off as the person in charge of ACF development. We will continue to support the development of industrializing countries from the viewpoint of environmental technology.
Profiles
Masaaki Yoshikawa
Energy Technology Laboratories
Bio & Chemicals Team
Masaaki Yoshikawa
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