Options When Shutting Down an LFG Electricity Project
LMOP is providing information on options that landfill owners and other owners of landfill gas (LFG) electricity projects may have when their power purchase agreement (PPA) is nearing expiration. In this context, a PPA is a contract between a renewable energy generator and purchaser that defines all the business terms of the agreement between the parties. This page provides options for entities seeking to minimize landfill methane emissions as they embark upon the process of shutting down an LFG electricity project.
When a landfill can no longer sustain an LFG energy project due to declining gas quantity or quality, there are several options to minimize LFG emissions even when the LFG energy project is no longer operational.
The options in order of most to least effective in minimizing methane emissions are:
- Continue to operate active LFG collection system and flare.
- Convert active LFG collection system to passive system with vent flares.
- Apply biofilters to selected wells or biocovers in selected hotspots.
- Free vent through flare or selected LFG wellheads.
The options presented here can be combined in some cases. For example, a landfill with an active gas collection system may opt to cap or close only selected inactive wells or install solar vent flares on wells in older areas of the landfill, while still maintaining an active vacuum on more active areas. Options associated with shutting down active gas collection systems should be implemented in a targeted and phased approach to avoid build-up of excess pressure or release of fugitive methane emissions.
Note that this resource is not intended to provide a detailed analysis; each option should be carefully evaluated with a professional based on site-specific landfill conditions and analysis of gas collection system data, as well as any regulatory requirements or permit conditions.
Back to Toolkit for Expiring LFG Electricity PPAs page.
Review the basic criteria below for each option and select "Learn more" for those of interest to read about the potential benefits, pros and cons, economic considerations and other information.
Continue to operate active LFG collection system and flare
This option may be worth considering if:
- Landfill still has sufficient methane content to be able to support combustion and maintain flame stability at the flare.
- Landfill has concerns about gas odor and/or migration.
Learn more about continued system operation
Convert active LFG collection system to passive system with vent flares
This option may be worth considering if:
- Landfill has gas methane content above 30 percent for efficient flare combustion, adequate gas pressure to move gas to the flare and gas flow between approximately 2 and 140 cubic feet per minute.
- Odor is a concern or landfill wants to minimize hazards related to flammable or toxic gas migration (e.g., nearby residences, structures, brownfield redevelopments).
- LFG is not prone to escaping laterally through surrounding soil.
Learn more about converting to a passive system
Apply biofilters to selected wells or biocovers in selected hotspots
Biofilters may be an option worth considering if:
- Landfill (or area of a landfill) has declining gas flow or has passive vents and declining gas quality.
- Gas wells are not producing significant methane and are not under vacuum to an active collection system.
Biocovers are an option worth considering:
- For all landfills including uncontrolled and older landfills with a passive or active gas collection system.
Learn more about biofilters and biocovers
Free vent through flare or selected LFG wellheads
This option may be worth considering if:
- Rural landfill without nearby neighbors to be affected by odor.
- Landfill with declining gas flow and methane content.
- Landfill does not have permit or other requirements to actively collect and combust gas.