Purification of biogas by vacuum pressure swing adsorption was evaluated to produce fuel grade methane (FGM). Two different adsorbents were employed to evaluate the process performance with equilibrium- and kinetic-based adsorbents. Carbon molecular sieve 3K was employed as the example of a kinetic adsorbent because methane diffusion is extremely small. A five-step cycle configuration (feed, intermediate depressurization, blow down, purge, and pressurization) was employed to compare with results obtained with a four-step cycle without intermediate depressurization. The effect of different operating variables like step times and pressure conditions of the cycle was analyzed.

A solid value proposition for biogas operators: Biogas producers who utilize the Biogas Optimizer service will be able to experience:
* Higher biogas production (a better utilization of digester capacity)
* A more stable biogas production (thus able to maximize ROI on CHP or gas upgrading units)
* Protection against process disturbances and better management routines to avoid process problems
* Detailed process monitoring and diagnosis leading to a cost efficient plant operation
* A faster start-up of bioreactors