Food & Climate
An expert found that the cost of avoiding CO2 emissions per ton when composting food waste is several times greater than the cost of remediating the carbon damage.
landfills aren’t built to help food break down cleanly. When food waste ends up buried under other trash, it quickly uses up the oxygen in its immediate surroundings.
At first, some decomposition happens with oxygen, which releases carbon dioxide – still a greenhouse gas, that’s 80 to 85 times more powerful than carbon dioxide over a 20-year period.
But once the oxygen’s gone, the process switches. Now you’ve got anaerobic decomposition, which happens without oxygen. This is where methane starts building up.
And unlike compost piles, which stay exposed to air and rely on oxygen, landfills are packed tight. That makes them perfect methane factories.
Composting does the exact opposite. It keeps oxygen in the mix throughout the process. That means no methane. Plus, it turns food scraps into something useful: a natural fertilizer that can go back into farms and gardens, according to a report seen by “Food & Climate” platform.
Composting isn’t cheap – yet
Some cities, especially in recent years, have started composting programs to cut down on landfill methane.
One recent study examined how composting plays out in real life, based on actual data. The study concentrated on places such as Austin, Texas, where there are programs set up to allow people to compost at home.
On average, the program reduced organic waste output by roughly 2.3 pounds per household per week. That’s a good start, but it’s only about 30% of what a typical American household discards a week.
There’s also the question of participation. Unlike cities such as San Francisco, many places don’t enforce composting. That means it’s optional – and a lot of people skip it.
Jackson Somers is an assistant professor of agricultural and resource economics in the College of Agriculture, Health and Natural Resources (CAHNR), said: “As individuals, we produce a lot of food waste, and it’s something we should be cognizant of. From there, you should compost if you want to compost,” said Somers.
“I think, inherently, we don’t want to be wasteful. But for some people it’s just a high burden of effort.”
Even with some success, the economics are tricky. According to Somers’ analysis, it currently costs about $478 to avoid emitting one ton of CO2 through composting programs.
By comparison, the “social cost of carbon” – a number economists use to estimate the damage caused by each ton of carbon emissions – is set at $51.
That means composting, at least in small-scale residential programs with low participation, isn’t cheap when measured in dollars.
“With current programs, given the infrastructure we have – these programs are really expensive for the savings we see,” Somers said. But that doesn’t make composting a lost cause.
No universal fix for food waste
The cost of building new landfills is rising fast. Once current landfills are full, finding and building new ones will be a big financial burden for many cities. So building composting infrastructure now might save money down the road.
Also, the social cost of carbon isn’t fixed. As scientists understand more about climate change, the estimated damage from each ton of carbon goes up. That means composting could become more cost-effective over time – even if the upfront price is high.
“As we learn more about our impact, composting programs may become cheaper from an environmental sense,” Somers said.
The study focused on households, but Somers pointed out that restaurants, grocery stores, and other businesses throw away massive amounts of organic waste. That’s where composting could really move the needle.
“That’s where I think you can see real savings. I think that’s something we should consider more than we do,” said Somers.
Composting might also bring unexpected benefits. Large cities with lots of exposed food waste deal with more mess and public health concerns. Composting can help reduce that and keep neighborhoods cleaner.
“Keeping rats and other pests out of neighborhoods certainly goes into the calculus too,” Somers said.
“How many people get sick from rats? How much do we dislike seeing rats running around on the streets? It’s important to factor in other impacts, not just environmental.”
Different communities need different solutions. Demographics, geography, and even local habits all shape what works best.