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Asahi Kasei to demo new adsorbent upgrading tech

Asahi Kasei to demo new adsorbent upgrading tech
The Kojima Sewage Treatment Plant, Kurashiki, Okayama Prefecture, Japan (photo courtesy Asahi Kasei).

Japan-headed Asahi Kasei Corporation, a global developer of fiber products, chemicals, and electronics-related materials, has announced that it has concluded an agreement with Kurashiki City, Okayama Prefecture, to hold a trial to evaluate and demonstrate the performance of a newly developed biogas purification system at a sewage treatment plant in the city.

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On September 15, 2022, the Mizushima Works of Asahi Kasei’s Production Center and Kurashiki City concluded 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.

New highly-selective adsorbent

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 (graphic courtesy Asahi Kasei).

Utilizing Asahi Kasei’s newly developed adsorbent, K-GIS zeolite, which selectively adsorbs carbon dioxide (CO2), the biogas upgrading system will produce high-purity methane (CH4) gas (biomethane or renewable natural gas – RNG) by removing CO2 from raw sewage gas.

Unlike conventional adsorbents which adsorb CH4 together with CO2, K-GIS zeolite adsorbs almost no methane.

This enables the upgrading system to efficiently separate and recover high-purity methane while recovering high-purity CO2.

Growing global demand for biomethane

Raw biogas from sewage sludge, landfills, anaerobic digestion (AD) plants, etc., consists of approximately 60 percent CH4 and 40 percent CO2.

While the use of biogas as a carbon-neutral fuel is expanding, it is in its upgraded form as biomethane or RNG as a direct substitute for pipeline-grade fossil gas in Europe and the United States (US) which is expanding even more rapidly.

If biomethane production using the biogas upgrading system is combined with carbon capture and utilization or storage (CCUS), the cycle would be carbon negative.

Demonstration trial

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

Biogas flow at the Kojima Sewage Treatment Plant in Kurashiki City, and the demonstration trial using the biogas upgrading system (graphic courtesy Asahi Kasei).

In the demonstration trial, the separated gases are subsequently returned to the biogas fuel stream for generating electricity.

Asahi Kasei will design, install, and operate the upgrading system, and evaluate and demonstrate its performance while Kurashiki City will provide biogas generated from sewage sludge and the site for the demonstration trial.

Commercialization of the upgrading system is expected around 2025 or 2026 following additional trials in countries or regions where biogas purification is performed.

The technology will also be applied to CO2 separation and recovery from gases other than biogas.

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