Landfill-gas-to-biomethane via a new carbon capture and utilization technology: One-pot sodium chloride batch mineralization

Abstract

A new landfill-gas-to-biomethane route adopts a new carbon capture and utilization process via sodium chloride (NaCl) mineralization. The new process exports chlorine (Cl2), dense carbon dioxide (CO2), hydrogen (H2) and sodium carbonate (Na2CO3). Process absorbs CO2 from landfill-gas with aqueous NaOH/Na2CO3 in batch multi-purpose columns that execute several processing steps in one-pot; namely: CO2 absorption; sodium bicarbonate (NaHCO3) precipitation; NaHCO3 filtration driven by pressurized CO2; NaHCO3 breakage to Na2CO3 via hot CO2 injection; Na2CO3 cooling via cold CO2 injection; and solid Na2CO3 disposal through column lateral doors. The one-pot columns avoid investment with several steady-state complex equipment like bubble-columns, centrifuges, filters, solid dryers, heaters, mud pumps and solid transporters. The depleted solvent from the one-pot columns is regenerated via steady-state, high current-density, brine electrolysis wherein solvent continually feeds cathodes, while brine continually feeds anodes as sodium source. Sodium reaches the cathode through selective Flemion F9010 ion-exchange membrane. CO2 is partially mineralized to Na2CO3 and partially exported as supercritical CO2. Process output-ratios per captured CO2 are: 1.159kgNa2CO3/kg, 0.7754kgCl2/kg, 0.4299kgCH4/kg, 0.0219kgGREEN−H2/kg and 0.51875kgCO2/kg, while the input-ratios are 1.2782kgNaCl/kg, 0.197kgH2O/kg and 1.7495kWh/kg. The new landfill-gas-to-biomethane (480,000Nm3/d landfill-gas) was evaluated environmentally and techno-economically reaching 48.6MMUSD investment, 112MMUSD/y revenues and 418.34MMUSD net value (30 years).