Economic viability of LFG recovery under the CDM mechanism

This paper examines the viability of investment in landfill gas (LFG) recovery and power generation under the clean development mechanism (CDM). The analysis is conducted at a prototype closed landfill with 4 million tons of organic waste and a CH₄ generation potential of 19.8 to102.6 m³/ton of waste estimated on the basis of field measurements. Five power generation technologies were compared including reciprocating internal combustion engines, gas turbines, organic Rankine cycle engines, Stirling cycle engines, molten carbonate fuel cells and solid oxide fuel cells at a capacity of 0.5 or 1 MW. None of the tested technologies exhibited favorable economic viability at the measured LFG emission rates. Using larger emission rates, certain schemes could pay back within a period of 7 years depending on the size of the generator and the cost of the power generation technology. Therefore, CDM initiatives are not always viable particularly in developing countries with waste streams characterized with high organic fraction. They need to be based on careful examination of waste characteristics and landfill history which are closely correlated with the magnitude and trend of LFG emissions.