Assessment of operations and design strategy controls to improve landfill gas utilization opportunities

摘要

Although landfill gas (LFG) has many potential beneficial uses, the initial capital costs required for constructing collection systems and utilization–cogeneration systems are high. Collection and combustion–utilization system must continue to function for many years to reap the benefits of investment. To improve the economics of recovery projects, opportunities to accelerate the generation of LFG and operation and design strategies to improve capture potential and recovery efficiency from landfills are examined. In this paper, mathematical models and input values are used from literature to reflect how fundamental principles that influence LFG generation can be manipulated to improve LFG collection utilization. Model coefficient values are changed to represent changes in landfill design and (or) operational strategies to improve the LFG generation rate. A first-order decay model is used to estimate gas generation for six scenarios. Modelling results (methane flow rates) indicate that moisture elevation, leachate recirculation, and addition of heat, increases the potential gas generation rates, with the highest impact relating to leachate recirculation with heat. Net present values (NPVs) are calculated for each of the six scenarios, based on capital and operation and maintenance (O&M) costs to estimate the economic feasibility of each scenario. The NPVs for each scenario are compared to the revenue generation potential through the sale of electricity and carbon credits (emission reduction credits) through LFG combustion. Based on the NPV estimates, leachate recirculation with heat addition has the highest economic feasibility.