Landfill Gas to High Btu Gas
A high Btu project involves the conversion of raw landfill gas into pipeline quality gas for introduction to a natural gas transmission or distribution line. In some cases, the gas is delivered directly to an end user. A high Btu plant processes the gas by removing the majority of the non-methane components including CO2, water, and other volatile and non-volatile organic compounds to attain "pipeline quality" gas. This complex process has numerous variables that need to be maximized in order to be cost effective and efficient. At the end of the gas processing chain the purified LFG is typically compressed and then sold into a natural gas pipeline or to a dedicated end user under long-term contracts at prices only slightly discounted from natural gas. The goal is to produce processed gas that meets or exceeds the requirements of the customer at all times in the most cost efficient manner possible while simultaneously adhering to all environmental restrictions of both the landfill and the gas processing plant.
There are essentially four proven commercial technologies available to process raw LFG to high Btu gas that are commonly known by the following names: Pressure Swing Adsorption ("PSA"), Membrane Filtration, Selexol, and Kryosol. Selexol and Kryosol are registered trade names for distinct proprietary processes. All four of these technologies have similar features, but are distinguished primarily by the means employed to separate carbon dioxide from methane in raw LFG. Each technology has advantages and limitations, the knowledge of which is critical to selecting which technology is best suited for a project. As in any process operation, experience, expertise and training are the keys to cost effective and efficient operation.
The natural gas industry is often reluctant to consider taking what it considers to be off-specification processed landfill gas into its transmission or distribution pipelines. This reluctance is rooted in concerns about the corrosive effect of off-specification gas on its pipelines and concerns that the utility's own customers will notice a drop in heating quality of their product.