ARC Southern is a project developer that is looking for economically viable options where we develop the land fill gas system and convert it to electricity and transmit it to the local grid. The intent of this write up is to give an overview of what LFG electricity generation is all about. Arc Southen is constantly looking for projects, which provide LFG gas rights and finding ways to help local communities develop “green energy” projects, such that it generates revenue for the city, and improves the local economy.

What is land fill gas?
Landfill gas, which consists mainly of methane and carbon dioxide, is produced when organic wastes in landfill sites decay. Landfills over a certain size are required to flare, or burn, the gas in order to reduce the hazard of gas build-up. Although landfill gas is primarily a pollutant that needs control, the methane it contains makes it valuable as fuel to power an electric generator. Landfill gas was first used as a fuel in the U.S. during the late 1970s. Since then, the technology required for its collection and use has developed steadily. This method of producing renewable energy is now regarded as one of the most mature and successful in the field of green power.

Can you provide more details on electricity generation using land fill gas?
The majority (more than 70 percent) of the LFG energy projects that generate electricity do so by combusting the LFG in internal combustion engines. The three most commonly used technologies — internal combustion engines, gas turbines, and microturbines — can accommodate a wide range of project sizes. Gas turbines are more likely to be used for large projects, usually for 5 MW or larger. Internal combustion engines are well-suited for 800 kW to 3 MW projects, but multiple units can be used together for projects larger than 3 MW. Microturbines, as their name suggests, are much smaller than turbines, with a single unit having between 30 and 250 kW in capacity, and thus are generally used for projects smaller than 1 MW. Small internal combustion engines are also available for projects in this size range. An LFG energy project may use multiple units to accommodate a landfill’s specific gas flow over time. For example, a project might have three internal combustion engines, two gas turbines, or an array of 10 microturbines, depending on gas flow and energy needs.

Is there a combined heat and power (CHP) application? Is CHP applicable to landfill gas projects?
LFG energy CHP applications, also known as cogeneration projects, provide greater overall energy efficiency and are growing in number. In addition to producing electricity, these projects recover and beneficially use the heat from the unit combusting the LFG. LFG energy CHP projects can use internal combustion engine, gas turbine, or microturbine technologies.

Less common LFG electricity generation technologies include a few boiler/steam turbine applications, in which LFG is combusted in a large boiler to generate steam used by the turbine to create electricity. A few combined cycle applications have also been implemented. These combine a gas turbine that combusts the LFG with a steam turbine that uses steam generated from the gas turbine’s exhaust to create electricity. Boiler/steam turbine and combined cycle applications tend to be larger in scale than the majority of LFG electricity projects that use internal combustion engines.