The BAUER GRU® Biogas Compressor range has been specifically designed for feeding biogas upgrading systems. The function of the biogas recovery compressor is to elevate the pressure of the incoming biogas from 1-7 psig (typical) to 90-230 psig, which is the operating pressure requirement for most PSA/membrane type gas upgrading systems. BAUER offers a complete GRU system size range from 10 HP to 750 HP (7.5-560 kW). At the heart of every GRU compressor system is the legendary BAUER Rotorcomp® rotary screw compressor, which is world-renowned for exceptional durability and reliability. The sophisticated control system in the GRU senses pressure upstream of the unit, and automatically adjusts the compressor speed to modulate compressor output based on the availability of biogas from the source (landfill or digester). If there is an insufficient amount of gas available upstream for compression, the system automatically goes into standby mode for instantaneous compression capability when upstream gas pressure suddenly increases. This significantly reduces the occurrences of venting gas into the atmosphere, because the compressor is ready to operate instantaneously (instead of ramping up through normal start-up sequences after being completely shut down).