Energy & Environment

Compost: the Next Step in City Recycling Programs

Over the past decade, curbside yard debris and leaf collection programs have led to a dramatic increase in the amount of organic matter that is...
by | September 30, 2009

Over the past decade, curbside yard debris and leaf collection programs have led to a dramatic increase in the amount of organic matter that is composted instead of sent to a landfill. Nationally, the rate is 20 percent, up from 2 percent in 1990, according to the U.S. Environmental Protection Agency.

Now, a select number of cities are moving ahead with curbside recycling programs targeting another kind of organic matter: food waste. Contrary to popular opinion, banana peels and apple cores don't biodegrade gracefully in a landfill. Instead, the languishing scraps form methane, a greenhouse gas 20 times more potent than carbon dioxide.

To address that problem, San Francisco recently passed a stringent measure requiring all single-family households, businesses and multi-tenant buildings to compost food scraps. The law goes into effect later this month and is part of the city's "zero waste" policy, which aims to stop the flow of all waste to landfills and incinerators by 2020. The city is handing out free composting bins, and garbage haulers will accept the discarded food waste as part of the weekly trash and recycling pickup. Fines for noncompliance range from $100 for households to $1,000 for large waste generators. There are positive incentives for complying with the law, too: People who compost should see a reduction in their garbage rates, since haulers charge according to the amount of refuse collected.

Seattle is taking a different approach to the same problem. The city has had a voluntary curbside composting program in place since 2005. But last spring, Seattle began requiring households to rent a composting bin--it costs between $5 and $7 per month, depending on the size--or commit to tending a backyard composting pile. The Seattle directive, which applies only to single-family homes, does not impose a penalty for non-compliance. Rather, it relies on the monthly charge to encourage buy-in from residents. "People say: 'We're paying for it, we might as well do it,' argues Brett Stav of Seattle Public Utilities, the agency which administers the program. Since the policy went into effect, the city has signed up an additional 30,000 compost customers, bringing the total number to 140,000.

The city of Boulder, Colorado, also has launched curbside food composting, as have several small towns in Minnesota, including Hutchinson and Wayzata. From a climate-change perspective, these programs are beneficial because they inhibit methane production. How? In a compost pile, oxygen-dependent bacteria break down the organic material, leaving water and carbon--not methane, which is created in an anaerobic landfill environment.

There are other ways of mitigating greenhouse gases generated by food waste--namely, capturing methane from landfills and using it to produce energy. The Altamont landfill in California, for example, captures enough methane to power 8,500 homes. But despite the green-energy benefits, methane capture ultimately treats the symptom, not the cause. As David McDonald, a resource conservation planner for Seattle Public Utilities, puts it: "Landfilling organics creates greenhouse gases. Composting organics creates a net removal."

In any case, climate change is not the only argument for composting food waste. San Francisco's new mandatory composing program builds on a voluntary one, which already collects 480 tons of food waste per day, much of it from restaurants. The scraps are sold to Bay Area farmers and vintners as crumbly black compost--then sold back again in the form of fruits and vegetables to local residents. "We close the loop locally," city spokesperson Mark Westlund says. "That's what we are most proud of."


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