As municipal solid waste decomposes, it emits landfill gas (LFG) — a concoction of approximately 50 percent methane, 50 percent carbon dioxide (CO2) and traces of non-methane organic compounds. Both methane and CO2 are greenhouse gases, and methane is 21 times more harmful than CO2.
The U.S. Environmental Protection Agency’s Clean Air Act, carbon credits, federal incentives and a growing need for renewable energy are motivating utilities and landfill owners to recover LFG and convert it into electricity, boiler-grade fuel or pipeline-quality natural gas. For landfills with more than 2.5 million tons of solid waste, LFG recovery can be an additional source of revenue.
With recent combustion engine and turbine efficiency improvements, LFG conversion
into electricity produces more watts of electricity through lower heat rates. Through a vacuum system — a blower draws the gas from the landfill and delivers it to a plant — the gas is treated, then travels through a combustion engine, gas turbine or microturbine and generator before being placed on the local electric grid.
As the price of natural gas rises, conversion of LFG to pipeline-quality natural gas or compressed natural gas has become a more economically viable option for landfills near the end user or a natural gas pipeline. Since methane is the primary component of natural gas, this conversion is a natural extension of LFG recovery. Direct use of LFG for medium-British thermal unit (Btu) applications where LFG is fired as a heat source can be the most economical application. In high-Btu applications, LFG is treated further to remove impurities for pipeline-quality natural gas.
For more information, contact Keith Connor, 816-349-6690.