Design of a liquid-piston compressor for raw-wet-biogas to produce biomethane for vehicles and back up power.

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"Engas UK Ltd is developing a novel raw-wet biogas compressor to directly produce ultra high purity bio-methane for i) refuelling of natural gas vehicles, and ii) Cloud-based back up power. This backup power will be suited for Smart Grid services and off-grid power generation. This solution will also be exported to abroad where CNG vehicles are common and the electricity grid is often unreliable.**Problem:** There is often a lot of stranded biogas in smaller sewage treatment sites, landfill gas sites, and many existing biogas plants sites where moving raw biogas from one location to another location will create a significant business opportunity; unfortunately shipment of raw biogas is currently NOT feasible due to the high moisture content, high level of CO2 and corrosive H2S impurities. The moisture content in biogas will block the mechanical piston unless the gas is dried upfront of compression. Then CO2 will liquefy during compression at above 60bar at ambient temperature causing serious blockage of piston/valves etc. H2S in raw biogas will also cause corrosion inside the compressor. Drying of raw biogas is inefficient due to the relative humidity causing a high level of surface water in raw biogas.**Solution:** Engas UK is developing a technology where wet-corrosive biogas having high CO2 content will be compressed and dried and the CO2 will be separated thus producing about 97% Biomethane at 200-250bar, which can be then shipped to a different location for usage e.g. refuelling of vehicles, or for power generation as back up power replacing diesel generators. There is an ongoing debate to phase out diesel backup generators to reduce local pollution and for example, the Government of Delhi has banned the use of diesel generators in Delhi from Nov 2017 to reduce the air pollution, which opens up a large market for bioCNG powered back up generators.At 250 bar biomethane has 3 times greater volumetric energy density (kWh/lt) than hydrogen, and 3 times greater energy density than the best Li-ion batteries, which will be ideal for energy storage at the most economical options for £/kW installed, and £/kWh delivered.The above solution addresses all three aspects of **energy trilemma of ""Affordable, carbon neutral, high efficiency, and energy security.** This solution would be suited for stranded biogas from existing sources and also to convert the organic waste to Biomethane at dairy farms, pig farms, new sustainable housing projects, University Campus, business parks etc."