Landfill Gas System Considerations at High-btu Landfills

There are generally three broad categories of landfill-gas-to-energy (LFGTE) projects: electric power generation, medium-BTU industrial fuel; and high-BTU pipeline gas. During initial feasibility studies, landfill owners and developers should weigh the advantages of each with regard to the technology, local markets, landfill conditions, and site proximity to potential users. There has been an increase over the past ten years in the number of high-BTU projects developed in the U.S. This paper will provide a discussion of the reasons project owners are selecting high-BTU projects. The author has been involved as both an owner’s representative and consultant in a high-BTU project for over seven years. The paper will draw upon this experience to examine some of the challenges and opportunities in operating the project with respect to maintaining both environmental compliance and quality inlet gas. Some of these challenges are applicable to other technologies as well. This paper will discuss the advantages and disadvantages of high-BTU projects, and contractual considerations related to potential wellfield issues and compliance problems. BACKGROUND According to the Landfill Methane Outreach Program (LMOP), the EPA’s program to promote landfill gas (LFG) as a renewable fuel, there were 37 active high-BTU landfill gas treatment projects in the United States as of July 2011. This represents approximately six percent of the 558 operating LFGTE projects nationwide. This number has increased in recent years due primarily to the availability of new technology that allows smaller projects to be cost-effectively implemented, increasingly stringent air emissions restrictions, and demand for renewable natural gas in certain local markets. Landfill owners and developers have several technologies to choose from, and must consider many issues in the planning and operation of their next project. The advantages and disadvantages of high-BTU should be considered in this process. As the minimum threshold flow rates for high-BTU projects continue to decrease, the U.S. is seeing more of these projects constructed. With the availability of renewable energy credits (RECs), the right location, and high efficiencies, high-BTU landfill gas projects may be attractive for a site, even when natural gas market prices are depressed. High-BTU projects, perhaps even more so than other technologies, should be addressed with a holistic approach. The possibility that perimeter collectors or separate collection systems may be required to maintain environmental compliance needs to be considered. Pipeline specifications are not consistent throughout the nation, and can change between states, utilities and regional locations, adding the risk of additional costs. Stringent compliance monitoring, consistent with the Federal New Source Performance Standards (NSPS) and state-specific regulations, should be an integral part of any project. Failure to address these considerations can pose operational problems and incur unplanned costs for either or both parties. POTENTIAL HIGH-BTU ADVANTAGES High-BTU systems, like the other technologies available, have certain advantages and disadvantages that need to be considered during preliminary feasibility studies. There are three high-BTU processes within this category: membrane filtration, pressure-swing adsorption, and amine scrubbing, which should be considered on their own merits. The original high-BTU systems were only cost-effective for larger landfills. However, over the past decade, technology has reduced the minimum operating thresholds for profitable high-BTU projects. Today’s systems tend to require lower system operating pressures, and are much more modular. This has reduced some of the significant capital costs such