Smarter Leftovers

Food accounts for about one-fifth of what goes into municipal landfills, and companies are looking for new ways to repurpose what we don’t eat. Some farmers use leftovers to feed their animals, and companies in California and Ireland are turning edible trash into pet food. Better systems to collect and distribute excess food from grocery stores and restaurants could help feed the hungry. Such food recycling is difficult and labor-intensive because it has to be done very quickly, but as droughts challenge agricultural production around the world, it could become more common.

Garbage Power

Food can also be turned into fuel through anaerobic digestion, a natural process during which microbes break down organic matter in the absence of oxygen. Farmers have used this process for years to make biogas out of manure; now new machines can speed things up. Anaerobic-digestion facilities are expensive to build, but they can be profitable if companies have a steady supply of food waste, as they would in the growing number of cities and states that have banned restaurants and grocery stores from sending large amounts of leftovers to landfills. Someday, businesses could build their own digesters, says Thomas DiStefano, a civil and environmental engineer at Bucknell University. Michigan State University has two such digesters that turn food waste from dining halls into electricity for the campus.

Burning garbage is another way to turn trash into fuel (usually by making steam, which turns turbines). The first trash incinerator in the U.S. was built in 1885, and until the 1980s, we burned much of the waste we couldn’t (or didn’t) recycle. But scientists discovered that dioxin emissions from incineration plants caused cancer and birth defects. The technology has since improved, and today’s plants are so clean that in Europe, builders are putting them in the middle of cities so they can power nearby households. In Copenhagen, a ski slope will be built atop one.

Plasma gasification, an experimental technique, could eventually replace incineration as an even cleaner and more efficient way to get rid of trash, says Juliette Spertus, an architect who has studied waste management. The process involves heating waste under pressure to produce syngas, a substance that can be used to make liquid fuels and other chemicals. Another process, called pyrolysis, also uses heat to turn trash into fuel. Both techniques are currently expensive and can process only small amounts of waste at a time, but they could become viable as space in landfills becomes increasingly scarce.

Ending Trash for Good

If rocket technologies improve, Staley says, we might one day blast trash into space and use the sun’s heat to burn it. But given that our planet has limited resources, burning them after one use probably isn’t the answer. Some environmentalists want to prevent companies from making nonrecyclable materials in the first place, and a few have suggested alternatives. A European research group called Zerowin, for example, designed a laptop made of recycled materials whose components can be reused. (Most computers end up in landfills, potentially leaking chemicals into the ground.) Joachim, of Terreform one, says the planned obsolescence of products should be outlawed. So-called extended-producer-responsibility laws could require manufacturers to fund and manage the recycling of their goods so that the private sector, rather than the public, is responsible for products at the end of their life, giving companies an incentive to make their products last longer. The beginning of the cycle, not the end, might be when we can most effectively eliminate trash.



A Brief Chronicle of Garbage