Low-concentration Coal Mine Methane Concentration Technology to Make Efficient Use of Coal Mine Methane Gas Released into the Atmosphere

Overview

Coal mine methane (CMM) with 30% or less methane concentration (low-concentration CMM) has been unutilized and vented to the atmosphere after extraction from coal seams to ensure safety of workers mining coal, being a cause of global warming. Osaka Gas has been working on developing a low-concentration CMM concentration technology to utilize otherwise unused low-concentration CMM as fuel for gas engines and gas boilers and to promote energy-saving and environmental protection efforts.

Features

• 1. The concentration technology concentrates low-concentration CMM with Osaka Gas's proprietary material technology, which adsorbs methane selectively from an air-methane gas mixture.
• 2. The technology enables utilization of methane otherwise released to the atmosphere with its global warming potential 21 times higher than that of carbon dioxide. A reduction of greenhouse gas emissions by installing one standard commercial unit (CMM flow rate: 2,000 m³/h) is expected to be approximately 40,000 t-CO₂ a year.
  This technology enables use of low-concentration CMM (which has been released into the atmosphere) for various applications. For example, concentrated CMM can be used as fuel for gas engine power generation and gas boilers as well as city gas for households and industrial uses.

Achievements and Future Plans

In fiscal years 2007 and 2008, Osaka Gas formed a joint research consortium (comprising five companies, including Chinese enterprises) to undertake a joint research project for “Development of Methane Concentration Technology Aimed at Effective Use of Low-concentration CMM (Coal Methane Gas),” under the auspices of the New Energy and Industrial Technology Development Organization (NEDO). A demonstration plant to concentrate CMM (CMM flow rate: 1,000 Nm³/h) was built at the Fuxin Coal Mine in Liaoning Province, China, and low-concentration CMM extracted from the coal mine was successfully concentrated through the demonstration.
Currently, Osaka Gas has licensed this technology to a company, which is promoting its commercialization.

Photo: Pilot Plant

Specifications for Standard Commercial Plant

Process capacity	2000 Nm3/h
Concentration performance	25% or more
Methane recovery rate	90% or more
Operation	Automatic operation at the touch of a button
Energy savings	Approx. 3,000 kL/year
Greenhouse gas emissions reduction	Approx. 40,000 t-CO2/year

* Concentration performance (%) = Methane concentration of product gas – Methane concentration of feed gas

* Methane recovery rate (%) = (Methane concentration of product gas × Integrated volume of product gas) ÷ (Methane concentration of feed gas × Integrated volume of feed gas)