Validating LFG Generation Model With Recovery Rates From Mexican Landfills

Abstract

Landfill gas (LFG) recovery predictions obtained using Mexico Landfill Gas Model 2.0 were compared to LFG recovery rates from the two biggest landfills in Mexico (Mexico City Landfill called “Bordo Poniente” and Monterrey City Landfill “SIMEPRODE”.). The corresponding landfill characteristics (e.g. leachate levels and handling; use of covers and/or liners, compaction procedures, etc.) where analyzed and considered for the modeling in both cases, resulting in recovery efficiency rates and correction factors for each site. For Mexico City landfill, a pumping test was performed for a period of 25 days during a bidding process, started by Mexico City Government. 11 extraction wells were installed for the test along with a blower-flare system, with a capacity of 1,000 m3/hr. During the test period, individual well measurements were taken every 4 hours obtaining information such as: gas composition (CH4, CO2 and O2), vacuum pressure and gas temperature. Also a main measurement was taken every 4 hours at the blower-flare system in which obtained the total LFG flow in addition to the above information. Modeling results for Mexico City landfill show a good accuracy (below the actual recovery rate obtained during the test). For Monterrey City landfill, the recovery rates were obtained from the historical data from the LFG to energy (LFGTE) project running since 2003 by BENLESA. Only the information between 2009 and 2012 were considered due to the last expansion of the plant to 16 generators, 1.06 MW each. Modeling results for Monterrey City landfill, overestimated the actual LFG recovery for the last 4 years including 2012. The causes for the difference between modeled and actual recovery rates for both landfills were analyzed and recommendations to improve the modeling results and the recovery rates were made.