Methanation System for Upgrading Landfill Gas into Pipeline Quality Renewable Natural Gas by Thermocatalytic Conversion of CO2

可再生天然气(RNG)可以从垃圾填埋气(LFG)中生产，垃圾填埋气是有机材料分解的产物。由于垃圾填埋气含有大量二氧化碳(高达55vol%)，因此必须在使用前进行处理，这通常是通过变压吸附或膜分离来实现的。然而，这种方法与高昂的资本投资和运营成本有关，分离二氧化碳的利用市场有限。另一种方法是通过热催化甲烷化反应将垃圾填埋气中包含的二氧化碳转化为甲烷，方法是在催化床上将二氧化碳与氢(H2)反应。氢气可以利用无碳排放的可再生能源(风能、太阳能、水力发电)或低成本的剩余电力通过水电解产生。将LFG升级为RNG，与管道优质天然气完全可互换，是LFG燃烧的有益替代方案。使用清洁能源将LFG升级为RNG，作为化石天然气的替代品，减少了发电和住宅供暖产生的总体碳排放。使用RNG可以支持现有的天然气供应系统，同时消耗捕获的富含温室气体的原料，并可作为电力转换天然气基础设施的一部分，用于多余的能量存储和再分配。

Renewable natural gas (RNG) can be produced from landfill gas (LFG), a product of the decomposition of an organic material. Since LFG contains large amounts of CO2 (up to 55 vol%), it must be processed prior to use, which is conventionally done by separation using pressure swing adsorption or membrane separation. However, this approach is associated with high capital investment and operating costs and markets for utilization of separated CO2 are limited. An alternative approach is to convert the CO2 contained in LFG into CH4 via the thermocatalytic methanation reaction, by reacting CO2 with hydrogen (H2) over a catalytic bed. Hydrogen can be generated by water electrolysis using carbon emission-free renewable energy sources (wind, solar, hydro) or low-cost surplus electricity. Upgrading LFG to RNG, which is fully interchangeable with the pipeline quality natural gas, is a beneficial alternative to the LFG flaring. The use of clean energy sources for LFG upgrading to RNG as a substitute to fossil natural gas reduces the overall carbon emission resulted from power generation and residential heating. The use of RNG can bolster the existing natural gas supply system, while consuming captured feedstocks rich in greenhouse gases, and can be utilized as part of a power-to-gas infrastructure for surplus energy storage and redistribution.