So-called biodegradable products are likely doing more harm than good in landfills, according to research released today from N.C. State University.
Why? Because as they break down, they are releasing a powerful greenhouse gas.
“Biodegradable materials, such as disposable cups and utensils, are broken down in landfills by microorganisms that then produce methane,” says Dr. Morton Barlaz, co-author of a paper describing the research and professor and head of N.C. State’s Department of Civil, Construction, and Environmental Engineering. “Methane can be a valuable energy source when captured, but is a potent greenhouse gas when released into the atmosphere.”
Only about 35 percent of municipal solid waste goes to landfills that capture methane for energy use, according to U.S. Environmental Protection Agency estimates. Another 34 percent of landfills capture methane and burn it off-site, while 31 percent allow the gas to escape, the EPA estimates.
The accelerated rate at which these man-made biodegradable materials break down may exacerbate the problem. The Federal Trade Commission guidelines requires products carrying the "biodegradable" label to decompose within a relatively short period of time after disposal. But the rapid degradation may be harmful to the environment, since federal regulations do nor require landfills that collect methane to install gas collection systems for at least two years after the waste is buried. If materials decompose and release methane quickly, much of the gas is likely emitted before the technology is installed, which means less fuel for potential use and more greenhouse gas emissions.
The study concludes that a slower rate of biodegradation is actually more environmentally friendly since the majority of the methane production will occur after the gas collection systems are installed.