From organic waste to energy source: the biogas journey

Raw biogas is produced via anaerobic digestion, a process in which organic matter such as animal or food waste is broken down to produce biogas and biofertilizer. This happens in the absence of oxygen, in an anaerobic digester. Raw biogas from animal waste contains around 55% methane, 35% CO2 and traces of other gases such as H2S and other VOCs. In the final stages of production (upgrading), CO2 is removed from the raw biogas and compressed.

Capturing and compressing this CO2 is an essential part of the journey. Rather than being released into the atmosphere and triggering unwanted climate effects, it can be reused, injected into a CO2 pipeline, or stored underground.

STEP 1: Feeding the biogas upgrading processDuring this…

STEP 1: Feeding the biogas upgrading process

During this step, the ZM oil-free multistage centrifugal blower elevates the relatively low pressure of the raw biogas coming from the anaerobic digester to approximately 15 to 20 psig.

STEP 2: H2S removalDuring this step, the raw biogas is run…

STEP 2: H2S removal

During this step, the raw biogas is run through a bed of activated carbon which removes a large part of the H2S and VOCs from the raw biogas. H2S levels are reduced from approximately 1,000 ppm to less than 100 ppm.

STEP 3: Pressurizing the biogas for upgradingAfter the H2S…

STEP 3: Pressurizing the biogas for upgrading

After the H2S and VOC’s removal, the raw biogas is compressed in the GG gas screw compressor. Compression is up to 240 psig which is the required pressure for the next step in the biogas upgrading process.

STEP 4: Biogas upgrading – CO2 removalTo upgrade the raw…

STEP 4: Biogas upgrading – CO2 removal

To upgrade the raw biogas to renewable natural gas (biomethane), the CO2 needs to be removed from the raw biogas. This happens through membranes containing specifically designed fibers which separate the CO2 from the remaining methane in the raw biogas.

STEP 5: CO2 compressionFinally, the removed CO2 is…

STEP 5: CO2 compression

Finally, the removed CO2 is compressed using a high pressure CO2 compressor.

Find out more about the process

Move around the setup in any direction to discover the 5 steps in biogas production.

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