Methane at the Landfill: Compact Liquefaction Without a Plant

Classical methane liquefaction cools everything in the gas to –162 °C and is built for millions of tonnes a year: a plant, a terminal, ships and a cold chain. Landfills, biogas digesters, mines and small wells produce methane in flows thousands of times smaller, and for them this scale is unreachable, so the gas is flared or released into the air, although methane warms the climate 28 times more strongly than CO₂ over 100 years. This paper describes a compact scheme that reverses the order of the classical process: concentrate and clean first, cool only what is sold. The gas is concentrated on TEGA, ARBOK's graphene-like adsorbent, in three or more parallel chambers regenerated under vacuum; carbon dioxide and oxygen are removed; the gas is dried and polished; and only then a vacuum cryo-loop on isopropanol, driven by CrioJet cold, cools the methane in a containerized unit on the site. Household cylinders receive compressed gas, and liquid methane serves those who must store and move large volumes. An average landfill at 70% capture yields about 2.4 million m³ of gas a year at 90% methane, about 22,000 MWh, and brings EUR 5–7 million a year together with leachate treatment and carbon credits, with a payback of 5–7 years. The same scheme applies to city sewage treatment plants with sludge digesters (60–65% methane), farms, food plants, palm oil lagoons, pulp and paper mills, small oil and gas wells and closed coal mines. At natural gas wells the same cold can also separate helium. Keywords: methane, landfill gas, biogas, liquefaction, TEGA, CrioJet, adsorption, helium, small-scale LNG