Starting next week, food-waste recycling will be mandatory in San Francisco. No more banana peels and uneaten Brussels sprouts entombed in plastic in a landfill — they’ll now be headed to a more useful place.
Under the city’s new Universal Recycling and Composting Ordinance that takes effect Oct. 21, all residents must carefully sort their trash into recyclables (cans, bottles and paper), trash, and compostables, meaning food waste, plant trimmings, soiled paper and other items that can be converted to compost.
In keeping with the city’s ultra-green image, the San Francisco Board of Supervisors voted 9-2 earlier this year to pass the ordinance in an attempt to do away with landfills and incinerators entirely — and, in the process, to cut emissions of greenhouse gases. Landfills produce methane, a global warming gas that is 23 times more potent than carbon dioxide.
Food waste composting isn’t new. Many of San Francisco’s residents and restaurants already send some 400 tons of food scraps to Recology’s Jepson-Prairie composting facility in Vacaville.
The ordinance now makes it mandatory. And the penalties — $100 per violation for residents, $500 for businesses — are significant enough to encourage even the recalcitrant, or merely lazy, to get in step with Mayor Gavin Newsom’s goal of zero waste by 2020.
The city already diverts almost three-quarters of waste away from its landfill. According to Robert Reed, a spokesman for San Francisco collectors Sunset Scavenger Co. and Golden Gate Disposal & Recycling Co. (both subsidiaries of Recology), the food waste-to-compost is an idea whose time has come.
Want to see which communities added food scrap composting just in the last 30 days? he asks. Type "food scrap compost" into Google and click "news" at the top of the page.
The results are surprising, and Reed is right. Composting is a valuable tool that experienced gardeners use to enrich soil worn out by repeated plantings. Compost encourages microbial activity, improves soil structure and enables better water retention. In and around San Francisco, the priceless compost from Recology is used to enrich organic farms and vineyard soils, or offered for resale to garden centers and landscapers.
Compost isn’t just good for soils, though. It’s also good for the environment, because making compost removes materials from the waste stream that, in landfills, contribute to the formation of greenhouse gases.
Of course, the same thing happens in a good compost pile, but during composting, the anaerobic digestion is accelerated to three weeks as compared to 30 years, meaning fewer gases are released. As Paul Hepperly, research director at the non-profit organic farming Rodale Institute, notes:
"Conventional farming — tilling the land, using commercial fertilizers, etc. — puts 3,700 pounds of carbon dioxide in the atmosphere per acre per year. Applying compost, which helps grow ‘cover crops’ that draw carbon in part from the air, returns 12,000 pounds of carbon a year to the soil."
Bob Shaffer, of Soil Culture Consulting in Glen Ellen, concurs. Shaffer, who has 35 years of experience as an agronomist, horticulturist and viticulturist, and consults with dozens of Bay Area vineyards, explains:
Plants are the ultimate builder of soil humus, and create the ultimate form of stored carbon in reference to natural or farmed soil. It is the roots that have the greatest ability to form and store carbon in soil, because they:
• turn into humus more easily compared to other forms of organic matter
• grow out in "swarms" in soil and deposit carbon in a large area, over time
• deposit carbon in soil while they are alive by exudation and by soughing off cells
• deposit carbon in soil when they die
• deposit carbon deep in soil where there is no other practical means to place carbon
So how effective is applying food scrap compost to growing cover crops? Shaffer says:
"On a scale of 1-10, we would rank compost as an 8, or even 10, depending on the quality and placement of the compost."
Wine growers and organic food producers are less interested in the carbon capture mechanisms of compost/cover crops than the results — vines heavily laden with prime wine grapes and State Fair-sized vegetables full of nutrition without the use of fertilizers.
Cline Cellars is a prime example. Located on a 350-acre estate in the Carneros District, and best known for its superbly zesty Zinfandels, Cline Cellars has also been using the compost for a no-till viticulture that relies on cover crops for about a decade.
"By regularly adding compost to vineyard soils you dramatically improve water retention, fertility and tilth. In addition, you disperse in the soil a magnitude of beneficial micro organisms which help the vines fully develop and produce full flavored grapes and thus, premium quality wine," says owner Fred Cline.
Cline Cellars also runs an organic farming operation called Green String Farm on 140 acres outside Petaluma. The farm, only part of which is under active cultivation at any one time to support sustainable agriculture and crop rotation, also uses the compost to grow about 100 acres of cover crops to nourish the soil for future food production.
Still, there’s no denying compost produces greenhouse gases. So the East Bay Municipal Utility District (EBMUD) has created a program to generate electricity from the methane gas produced by food waste decomposition through anaerobic digestion. Methane, when burned, releases less carbon dioxide than any other hydrocarbon fuel (i.e., natural gas, oil and coal) and it produces garden-ready compost.
The program is believed to be the first of its kind in the country. EBMUD engineers have been testing and refining it since 2006, when the EPA gave the utility $50,000 to study the process. The district plans to begin selling energy to the grid sometime in 2009 and estimates it will get 4.5 megawatts from the food waste-to-electricity program alone.
There are, of course, some iconoclasts who say no amount of diversion of food waste, or any waste, will do much good as long as the waste stream is made up primarily of industrial waste, or what Mother Jones writer Kevin Drum calls GNT, for Gross National Trash.
On the other hand, there’s Eleanor Roosevelt’s philosophy, which suggests that it is better to light one candle than curse the darkness.
Here’s your candle, Kevin.
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(Photos: Compost bin/iStock; Vineyard/Cline Cellars)