New York City Mayor Eric Adams announced last week that all of Queens’ 2.2 million residents will be able to put organic waste, including food and yard products, into a brown bin as part of the city’s new, expanded composting program. The city calls it the nation’s largest in the press release, and claims that it will enable the Department of Sanitation to turn food and yard waste into “clean, renewable energy.”
But for anyone who knows anything about composting, the promise of turning the compost into energy doesn’t sound right. It’s a bit like announcing a new child education program that will generate clean, renewable energy.
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“The proposal outlined here from NYC is greenwashing, plain and simple,” said Seth Gladstone, spokesperson for the nonprofit advocacy group Food & Water Watch.
Composting has nothing to do with creating energy. It is the process of turning organic waste into reusable soil. Rather than letting the food rot in a landfill emitting methane, a potent greenhouse gas, composting results in a different decomposition process that does not release methane. Composting, by preventing the creation and release of methane, offers tremendous environmental benefits. According to the Environmental Protection Agency, composting provides several other environmental benefits, including enhancing water retention and sequestering some carbon. (Closer to home, composting can create rich soil ideal for a kitchen or community garden.)
One thing composting does not do is produce energy, clean or otherwise. In order to produce energy, the waste has to be industrially processed and turned into what the energy industry has dubbed “biogas,” “renewable natural gas,” or RNG. (People more skeptical of the environmental benefits of biogas often prefer terms like synthetic gas.) Despite the branding, “biogas” is, in the words of researchers from the environmental nonprofit Sightline Institute, “chemically identical to fossil natural gas”—which is, after all, itself biogas, being composed of the remnants of dead plants and animals.
The supposed environmental benefits of synthetic gas stems from the fact that it can be made from the methane emitted from organic waste. As such, it is often presented as environmentally friendly because it doesn’t involve fossil fuels. But that label is very much disputed, especially when the organic waste used to produce synthetic gas could be composted. Making synthetic gas involves a process that essentially replaces the burning of fossil fuels with the burning of food waste with similar environmental consequences.
For the Queens program, “some material will go to compost, the rest will be digested for renewable energy,” Department of Sanitation spokesperson Vincent Gragnani told Motherboard, referring to the production of synthetic gas. “The relative share of each will depend on the amount of yard waste vs. food waste we collect,” but “much of the yard waste (especially larger, woody items)” will go to composting, while food waste—the kind currently collected and composted at community gardens around the city—will go to a facility that creates synthetic gas.
Admittedly, this is all a bit confusing to talk about because even people who disagree on the merits of synthetic gas use the same words in different ways. Everyone agrees the goal is “clean” and ”renewable energy,” but the disagreement is on whether synthetic gas counts.
Still, experts largely agree synthetic gas is no climate solution, and that calling it “clean” is a misnomer, especially when a viable alternative to avoiding those methane emissions through composting exists.
“Biogas is definitely not clean,” said Mark Jacobson, professor of civil and environmental engineering at Stanford University. “When it is burned for energy in people’s homes, it produces air pollutants. Plus, the transport and conversion of the waste to biogas takes energy, and much of that energy is not renewable.”
Gladstone said one big problem with synthetic gas facilities is they often leak the very methane they’re supposed to be preventing from entering the atmosphere, as is the Newtown Creek facility in New York where organics from the Queens program will be sent. The methane is also “flared,” or burned into carbon dioxide, another potent greenhouse gas, and then emitted into the atmosphere.
“Certainly, it is true that simply depositing food waste into landfill also can produce methane. It’s not ideal,” Gladstone said. “But, creating one problem to solve another is not a valid solution, either.”
“Legitimate composting operations even at large scale do not emit methane and that is a real solution to food waste and the downsides of food waste,” Gladstone said. “But biogas is not. Biogas requires digesters that produces methane that leaks into the atmosphere.”
Gladstone added that even the name of this program is clearly not accurate. “Composting and biogas are two completely different things that do not overlap in any way. One is a holistic, earth-friendly, climate-friendly way of transitioning food waste to healthy soil which does not produce methane…Biogas is essentially problematic for many of the same reasons as what we think of traditional fossil fuel operations as problematic.”
