Green energy recovery by blending treated biogas into town gas pipeline networks

Biogas can be converted into treated biogas or synthetic natural gas, which can be blended into town gas pipeline network at a designed mixing ratio. Specific gravity and calorific value of biogas are adjusted to satisfy gas safety and quality standard. Carbon dioxide pressure swing adsorption is selected and applied for specific gravity reduction and calorific value enrichment. 95% nitrogen, defined according to the flammability plot, is mixed with biogas for tuning the calorific value at the end of the process end. Gas interchangeability of the gas mixture of treated biogas and town gas was predicted by using maximum combustion potential (MCP) chart and their maximum mixing ratio for safe use was indicated. Gas interchangeability of the gas mixture was tested to confirm the prediction. The South East New Territories Processing Facilities were designed and built according to the above principle, and has been in operation to convert biogas into synthetic natural gas successfully since 2017.