Asahi Kasei to construct biogas purification system at sewage treatment plant in Kurashiki, Okayama, Japan 15.09.2022: – demonstration trial on CO2 separation/recovery utilizing zeolite Asahi Kasei and Kurashiki City today con-cluded an agreement to hold a trial to evaluate and demonstrate the performance of a bio-gas purification system (the System) at a sewage tr

– demonstration trial on CO2 separation/recovery utilizing zeolite



Asahi Kasei and Kurashiki City today con-cluded an agreement to hold a trial to evaluate and demonstrate the performance of a bio-gas purification system (the System) at a sewage treatment plant in the city.



Earlier in the day, the Mizushima Works of Asahi Kasei’s Production Center and Kurashiki City con-cluded a comprehensive partnership agreement for the realization of carbon neutrality in society. Advancing the demonstration trial for decarbonization is one of the provisions of the partnership.



The System refines high-purity methane gas (biomethane) by removing CO2 from biogas utilizing Asahi Kasei’s newly developed adsorbent, K-GIS zeolite, which selectively adsorbs CO2. Unlike con-ventional adsorbents which adsorb methane together with CO2, K-GIS zeolite adsorbs almost no me-thane. This enables the System to efficiently separate and recover high-purity methane while recov-ering high-purity CO2.



Figure 1: Crystal structure of the new adsorbent, K-GIS zeolite – the size of cavities in the crystal is slightly larger than the CO2 molecule, which allows CO2 to enter the crystal and be adsorbed while larger molecules such as methane are excluded.


Biogas from sewage sludge, garbage, etc., consists of approximately 60% methane and 40% CO2. While the use of biogas as a carbon-neutral fuel is rapidly expanding, it is also a source of biomethane as a substitute for natural gas in Europe and the U.S.




Figure 2: The flow of biogas – high-purity methane refinement is conducted mainly in Europe.



In Kurashiki City, electricity is generated using biogas derived from sewage sludge at the Kojima Sew-age Treatment Plant. The System will use a portion of this biogas for the demonstration trial.



If biomethane production using the System is combined with carbon capture and utilization or storage (CCUS), the cycle would be carbon negative. In the demonstration trial, the separated gases are recombined to biogas as fuel for generating electricity.



Figure 3: Biogas flow at the Kojima Sewage Treatment Plant in Kurashiki City, and the demonstration trial using the System.



Schedule:

Fabrication of equipment in November 2022
Start of installation in May 2023
Start of operation at the end of 2023




Location:



Kojima Sewage Treatment Plant, Kurashiki, Okayama Prefecture, Japan



Roles of participants:


• Asahi Kasei will design, install, and operate the System, and evaluate and demonstrate its perfor-mance


• Kurashiki City will provide biogas generated from sewage sludge and the site for the demonstration trial
Commercialization of the System is expected around 2025 or 2026 following additional trials in coun-tries or regions where biogas purification is performed.


The technology will also be applied to CO2 separation and recovery from gases other than biogas. The Asahi Kasei Group contributes to life and living for people around the world. It is expected that commercialization of the CO2 adsorbent and the biogas purification system based on original technology will help society to effectively utilize clean environmental energy.




- Henning Kühl - photos Asahi Kasei