The efficiency of processing methods is dependent on two major parameters: Firstly on the primary energy required for processing, and secondly on the methane losses incurred during processing. It is important to keep both variables as low as possible to maximize efficiency.
Energy requirements*
Of the methods previously used for biogas processing, pressure swing adsorption (PSA) is the most efficient solution. However, amine scrubbing requires only 41 percent of the electrical energy needed for PSA. Even if the cleaned bio-methane from amine scrubbing is raised to the same pressure as the gas processed by pressure swing adsorption, the amount of electrical energy saved is still 26 percent.
Methane loss*
Methane losses during biogas processing are very difficult to avoid from a process standpoint. However, they should be kept as low as possible for both ecological and economic reasons.
Methane losses are approximately equally high for pressure water scrubbing and pressure swing adsorption. With Selexol scrubbing, the methane loss can only be reduced to approximately two percent by connecting a second scrubbing stage downstream. However, this means twice as large a regeneration circuit for the scrubbing agent.
The high selectivity of the scrubbing agent with non-pressurised amine wash enables very high levels of methane purity with extremely low methane losses. This is the decisive factor for the efficiency of biogas processing.
*Source: Extracts from the conference transcript from the symposium „INNOGAS“, 27 October 2006 in Lutherstadt Wittenberg
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Gas treatment 
