Grass to Gas: Landfills Want Yard Waste

A landfill gas-to-energy plant in Conestoga, Pennsylvania.

When it comes to corporations fighting climate change, landfill owners don’t necessarily leap to mind. But in Michigan, the landfill industry is working to repeal a 19-year-old ban on the disposal of grass clippings and tree trimmings in dumps — on the grounds that the yard waste, mixed with typical garbage when buried, makes a perfect brew for what it terms renewable methane production.

Michigan enacted the 1990 yard waste ban to preserve dwindling landfill capacity.  The measure is estimated to have reduced incoming landfill volume by about 20% when it took effect in 1995.  A small but robust compost industry has sprung up to handle the thousands of tons of diverted yard waste and convert it to landscaping material.

Some landfills flare the gas currently, while some already sell it to electric utilities.

The proposal has picked up some support from regional and local governments, but other communities and environmental advocates are sharply critical, saying estimates of the amount of methane that would be captured by landfills are vastly overblown. (An industry consultant says the measure would produce enough energy to heat 200,000 homes.)

The critics say the policy change could lead to increased greenhouse gas emissions. Instead of generating carbon dioxide as the yard waste breaks down in the open air, when mixed with waste in landfills the leaves and grass clippings will generate large amounts of methane, 23 times more potent as a greenhouse gas, and the legislation would require only 70% of the total landfill methane to be captured. Landfills would derive more revenue from increased waste volumes and the sale of energy.

“Yard waste is not trash,” says James Clift of the Michigan Environmental Council.  “When properly handled, yard waste is good for the environment.  That has not changed.  Grass clippings if not collected and allowed to return to the lawn lead to a healthier lawn that needs less watering.  Secondly, all yard waste when combined and composted creates a soil enhancement that can benefit gardens and green spaces around the home. ”

The Michigan Chamber of Commerce has joined the waste industry in supporting repeal of the yard waste landfill ban. “We have to be able to add more to the landfills to get more out,” says the Chamber’s Doug Roberts.

Photo credit:  Lancaster County Solid Waste Management Authority, Pennsylvania.

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