{"id":6194,"key":"Biogas_CO2_scrubbing_project","title":"Biogas CO2 scrubbing project","latest":{"id":1207664,"timestamp":"2025-11-27T22:39:22Z"},"content_model":"wikitext","license":{"url":"https://www.appropedia.org/Appropedia:Copyrights","title":"CC-BY-SA-4.0"},"source":"The biogas comes off the digester by its own pressure and comes through the\n[[Biogas H2S Scrubbing|Sulphide stripper]], and is collected in a\ngas bag which has a air pressure switch gotten from an automatic washing\nmachine, which clicks in at about 12\" water gauge and out at about 2-3\".\nWhen the gas bag is full the switch clicks in and starts a simple air\ncompressor which only needs to pump the gas up to around 50-60psi.\nalthough the compressor can go much more than that.\n\nThe compressed gas is\nthen bubbled into the base of a vertical standing length of 6-10\" pipe\nabout 4-6metres high and 2/3 full of water. The pipe can be anything though\nPVC looks nice and clean. If you are lucky enough to have a high mains\npressure for your supply, you just feed that in through a partially opened\ntap. The water level is controlled by an exit float valve which bleeds\noff the highly gas charged water when the level gets beyond 2/3 to 3/4 way\nup the pipe. That water, when the pressure is released, will fiz just like\nsoda water.\n\nThe gas then comes off the top of the vertical pipe through a\npressure release valve which controls the whole operation, and goes into a\npressure cylinder for storage at what we call '''intermediate pressure'''. If your\nwater supply is at low pressure, then you will have to use an old piston\nwater pump or any type of positive displacement pump which can work at its\nlimit, say 150psi. It should be switched off and on along with the gas\ncompressor. This means that the gas compressor can also work up to that\nfigure, and the whole system shifts up a cog in terms of its efficiency and\nthe gas comes out the stripping column for storage at that much higher a\npressure (150psi) and correspondingly less volume.\n\nWe liked to get hold of old 500\nlitre LPG cylinders from hotels and the like. One farmer I knew got hold of\nan old railway locomotive boiler and used that. He actually had two. One\nalongside the biogas plant and another alongside his grain drier which was\nabout half a mile away. They were connected together by 3/4\" pvc water\npipe, which gave adequate gas transfer when the grain drier was working.\nJust make sure that you have a water drain tap on the bottom of your storage\ncylinder because everything gets warm and the gas will drop a lot of\nmoisture as it cools.\n\n== See also ==\n\n* [[Biogas]]\n* [[Biogas H2S Scrubbing]]\n\n== External links ==\n\n{{Page data\n| license = CC-BY-SA-3.0\n| keywords = Biogas\n| sdg = SDG07 Affordable and clean energy\n| description = CO2 scrubbing helps store biogas. Appropedia explains an easy method to capture and compress it for use.\n}}\n\n[[Category:Biogas]]"}