Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.
Today, we’re revisiting food waste. As we’ve said in some of our other episodes, the best way to tackle food waste is to prevent it in the first place. But, when it does come time to toss your kitchen scraps, where should they go?
We had Fatima Husain and Ashley Junger from our Possibly Team look into this.
Fatima Husain: Hi, Megan!
Ashley Junger: Hello!
Megan Hall: So, Fatima, to start us off – where do our food scraps go when we toss them?
Fatima Husain: After scraping your plate or the cutting board, your food can end up in one of three places: your trash bin, the sink disposal, or in compost.
Ashley Junger: And each of these destinations are associated with different environmental impacts, like releasing greenhouse gases such as methane.
Megan Hall: We’ve spoken a bit about methane before on Possibly – can you remind us how it’s associated with food waste?
Fatima Husain: Of course, To do that, let’s think about landfills – the place where food ends up if you put it in the trash. After about a few weeks at the dump, that food gets buried and is no longer exposed to open air.
Ashley Junger: And when that happens, microbes break down that buried food into methane, a greenhouse gas which, in the short term, warms the planet 80 times more than carbon dioxide does.
Megan Hall: Got it. So, food waste in landfills eventually ends up as greenhouse gases in the atmosphere?
Fatima Husain: Yes, though at some landfills, some of that gas is collected and used for energy. In Rhode Island, for example, landfill gas from the Central Landfill is captured and converted to electricity.
Ashley Junger: In 2023, there were nearly 500 landfills with landfill gas energy projects in the United States, with about 100 more planned or underway.
Fatima Husain: But even a landfill with methane capture can’t catch all of it. A recent report from the EPA estimated that over sixty percent of methane produced by landfill food waste isn’t captured and still makes it to the atmosphere.
Megan Hall: Got it. So the trash isn’t a great option. What about sink disposal?
Ashley Junger: When your scraps go into your sink disposal, they’re shredded up and travel through sewer pipes to your local water treatment plant.
Fatima Husain: On the way to the plant, microbes can start breaking those shredded scraps down into methane.
Ashley Junger: And then at the treatment facility, food wastes become part of sewage sludge. Depending on where you live, that sludge can end up in your local landfill, burned, turned into fertilizer, or processed for methane capture.
Fatima Husain: But just like with landfill gas energy projects, not all wastewater facilities have systems in place to capture methane. In fact, most don’t.
Ashley Junger: A recent study out of Princeton showed that wastewater treatment plants in the US emit nearly two times more methane than scientists previously thought. It’s about the same amount of methane that landfills produce.
Megan Hall: Wow – so what about composting?
Fatima Husain: Compared to the methane emissions associated with landfilling or your kitchen sink, compost is by far the best place for your food waste to end up.
Ashley Junger: During the composting process, microbes interact with food in the presence of air, which contains oxygen. When oxygen’s around, microbes break down food into carbon dioxide, not methane.
Fatima Husain: More and more cities including New York, Seattle and San Francisco have implemented municipal composting.
Ashley Junger: And even more have pick-up composting available by third parties.
Fatima Husain: Of course, if you have a backyard, or even a bin under your sink, you can compost your own food waste, turn it into nutritious soil, and keep heat-trapping methane out of our air.
Megan Hall: Great! Thanks, Fatima and Ashley!
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Possibly is a co-production of Brown University’s Institute for Environment and Society, Brown’s Climate Solutions Initiative, and the Public’s Radio.