By Gary Thomas
At a site in Laupheim, Germany, grass, maize and whole plant silage have been used for biogas production in the past four years. Erdgas Südwest processes the raw biogas into biomethane, which is then supplied through the own natural gas grid to end customers.
The commissioning of the first biogas processing plant at the site was done in 2008. Every hour, nearly 600 standard m3 of raw biogas is processed by Schmack Carbotech’s pressure swing adsorption. This quantity is good enough to power 2,000 four-person households.
In order to meet the rising biomethane demand, the operator planned to increase the production capacity. For this purpose, he selected ETW Energietechnik’s biomethane system based on its practical operational experience and the knowledge of the benefits of dry pressure swing adsorption. The key reason behind the selection was ETW Energietechnik’s capability to integrate the new technology into the current facility.
This is the first time where a Laupheim plant has produced biomethane using ETW Energietechnik’s PSA process control, which is a drastically different system from the proven systems used in Germany. The plant is able to produce high-methane content biogas with very low power consumption and methane loss. This means the delivery of 98% of the supplied methane to the natural gas grid and the remaining 2% methane is reverted back to the biogas plant’s biological process through an after-burning unit as a heat source. Along with the compression heat recovery, an overall heat output of 140 kW at 80° C can be extracted from the gas processing.
The system is highly economical as it consumes only 130 kW of power owing to the upgraded process technology and does not require additional supplies other than active carbon for desulfurization. It provides high operational stability and ecological advantages as it eliminates issues such as chemical substance handling, channeling, sediments, corrosion, winter conditioning, fresh water requirements and heat requirements.