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

“Engas英国有限公司正在开发一种新型的原湿式沼气压缩机，可以直接生产超高纯度的生物甲烷，用于1)天然气汽车的加油，以及2)基于云的备用电源。这种备用电源将适用于智能电网服务和离网发电。这种解决方案也将出口到国外，那里的CNG汽车很常见，电网往往不可靠。**问题：**通常在较小的污水处理场，垃圾填埋气场和许多现有的沼气厂场址有大量滞留的沼气，将生沼气从一个地方转移到另一个地方将创造一个重要的商业机会；不幸的是，由于高水分含量，高水平的二氧化碳和腐蚀性H2S杂质，原料沼气的运输目前是不可行的。沼气中的水分会阻塞机械活塞，除非气体在压缩前被干燥。然后，在环境温度下60bar以上的压缩过程中，二氧化碳会液化，导致活塞/阀门等严重堵塞。生沼气中的H2S也会对压缩机内部造成腐蚀。由于相对湿度导致原料沼气中的高地表水水平，原料沼气的干燥效率低下。**解决方案：**英国恩加斯正在开发一种技术，该技术将具有高二氧化碳含量的湿腐蚀性沼气压缩和干燥，二氧化碳将被分离，从而在200-250bar的温度下产生约97%的生物甲烷，然后可以运送到不同的位置使用，例如为车辆加油，或作为替代柴油发电机的备用电源发电。关于逐步淘汰柴油备用发电机以减少当地污染的争论正在进行，例如，德里政府已从2017年11月起禁止在德里使用柴油发电机以减少空气污染，这为生物天然气供电的备用发电机开辟了一个巨大的市场。在250 bar时，生物甲烷的体积能量密度（kWh/lt）是氢气的3倍，是最好的锂离子电池的3倍，这将是最经济的储能选择，安装成本为£/kW，交付成本为£/kWh。上述解决方案解决了“负担得起、碳中和、高效率和能源安全”的能源三难困境的所有三个方面。**该解决方案适用于现有来源的滞留沼气，也适用于将奶牛场、养猪场、新的可持续住房项目、大学校园、商业园区等的有机废物转化为生物甲烷。”

"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."