We design biogas upgrading plants through which methane can be separated from carbon dioxide. Unlike natural gas, biomethane is not derived from fossil sources but originates from biogas. This can be produced from many substrates such as agricultural waste, livestock manure, algae, or waste. Through a purification (upgrading) treatment, the purified gas can be used as flexibly as natural methane gas. Our plants offer: simple, safe, and reliable technology; very low operating and maintenance costs; very high efficiency of up to 99% CH4; CO2 treatment and recovery for industry.