LANDFILL GAS CONVERSION TO A CONTAMINANT-FREE METHANE-CARBON DIOXIDE REFORMER FEEDSTOCK FOR METHANOL SYNTHESIS

MUNICIPAL LANDFILLS PRODUCE GAS: SEVERAL MILLION STANDARD CUBIC FEET (SCF) PER DAY FROM A MODEST LANDFILL, AND UPWARDS TO 5-10 MILLION SCF/DAY FROM LARGE LANDFILLS. GAS GENERATION OF THIS MAGNITUDE CONTINUES LONG AFTER LANDFILL CLOSURE, PERHAPS FOR 15 TO 20 YEARS. LANDFILL GAS (LFG) IS ROUGHLY AN EQUAL MIX OF METHANE (CH4) AND CARBON DIOXIDE (CO2), WHICH BECOMES CONTAMINATED WITH MANY VOLATILE TRACE COMPOUNDS AS IT MIGRATES THROUGH THE LANDFILL. LFG COLLECTION SYSTEMS ARE INSTALLED PRIMARILY TO PREVENT OFF-SITE MIGRATION AND CONTROL ODORS; REDUCTION OF GREENHOUSE GAS EMISSIONS IS AN INDIRECT BENEFIT. MOST COLLECTED LFG IS SIMPLY FLARED TO CONVERT CH4 TO CO2, A NON-EXPLOSIVE, NON-TOXIC, LESS POTENT GREENHOUSE GAS. ECONOMIC AND TECHNICAL BARRIERS DISCOURAGE ENERGY RECOVERY FROM LFG. THE COST OF AVOIDED POWER IN MANY AREAS DOES NOT JUSTIFY THE CONVERSION OF LFG TO ELECTRICITY, WHILE THE TECHNICAL DIFFICULTY OF REMOVING CO2 AND TRACE CONTAMINANTS COUPLED WITH LACK OF NATURAL GAS PIPELINE ACCESS USUALLY CAUSES PROBLEMS IN THE CONVERSION OF LFG TO CH4. RESEARCH IS BEING CONDUCTED TO FURTHER DEVELOP TECHNOLOGY THAT CONVERTS LAW LFG TO A CONTAMINANT-FREE MIXTURE OF CH4 AND CO2 TO SERVE AS REFORMER FEEDSTOCK FOR METHANOL SYNTHESIS. NO HAZARDOUS SOLVENTS OR OTHER SEPARATING AGENTS ARE USED; CO2, AN ENVIRONMENTALLY BENIGN "GREEN" SOLVENT CONDENSED DIRECTLY FROM LFG, IS USED AS COLD LIQUID ABSORBENT TO REMOVE LFG CONTAMINANTS TO BELOW PPM LEVELS. TEMPERATURE AND PRESSURE ARE SELECTED TO PRODUCE A CONTAMINANT-FREE MIXTURE WITH THE DESIRED CH4:CO2 RATIO FOR METHANOL SYNTHESIS, ABOUT 2.3:1. METHANOL, EASILY STORED AND TRANSPORTED FROM A LANDFILL, ENJOYS AN EXPANDING READILY AVAILABLE MARKET, AND THEREFORE COULD MAKE LFG UTILIZATION PROFITABLE FOR RELATIVELY SMALL LANDFILLS. THE PHASE I OBJECTIVE IS TO DEMONSTRATE PRODUCTION OF CONTAMINANT-FREE METHANOL SYNTHESIS FEEDSTOCK GAS FROM LANDFILL GAS BY CONTAMINANT ABSORPTION WITH COLD LIQUID CO2. THE AMOUNT OF SIMULATED LFG GAS FLOWING TO THE LIQUID CO2 ABSORPTION COLUMN WILL BE ABOUT 30,000 TO 40,000 SCF/DAY, A SCALE SUFFICIENT TO DEMONSTRATE BOTH TECHNICAL AND COMMERCIAL VIABILITY TO MUNICIPAL LANDFILL OWNERS AND OPERATORS.