| Resumen | Biogas conversion into biomethane involves the removal of the largest possible amount of CO2 and H2S present in the biogas to achieve an energy content of the resulting fuel of approximate 10 kWh/m3 (Lower Heating Value). Currently commercial upgrading technologies are based in one of these two main principles: (i) the higher solubility of CO2 when compared to methane (in water or other solvents) or (ii) the size differences between the majority components. The different technologies present in the market consume large amounts of electric energy to compress the gas and generate the solubility or spatial-distribution gradients required by each technique. In this context, the high consumption of electricity of conventional upgrading technologies is considered as a drawback given the high prices of this commodity in comparison to the price of thermal energy and given the dependency of a supplier external to the facility to produce biogas. The investigation of novel upgrading technologies with low electricity consumption is key to boost the competitive production of biomethane from biogas. The use of Calcium Looping cyclic process (CaL), commonly used as a carbon capture technology, for the upgrading of biogas may strongly reduce the electricity consumption while demanding high-temperature thermal energy for the operation of the process which can be integrated in the system. The energy penalty of this novel CaL biogas upgrading technology may be significantly reduce when compared to existing commercial technologies such as direct use in internal combustion engines or PSA upgrading. |
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