These companies want to fight food waste thanks to microbes

“We have to deal with this waste somehow.”

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Meltem Urgun Demirtas

For companies interested in anaerobic digestion, however, methane production is the goal. Because these facilities are sealed, the mixture of methane and carbon dioxide produced by microbes, called biogas, can be captured and purified into biomethane, which can be used as a replacement for natural gas.

Some producers use this biomethane (also called renewable natural gas) or unpurified biogas on site, burning it to power their facilities. Others sell it to utilities, so it gets injected into existing natural gas pipelines and used to generate electricity at power plants, or used in homes for heating or cooking.

Overall, anaerobic digestion could provide a climate benefit, but the exact reduction in emissions will depend a lot on the details, says Troy Hawkins, a researcher at Argonne National Laboratory who studies the environmental effects of energy systems.

Divert works with over 5,000 retail stores across the United States to collect food waste and treat it using anaerobic digestion. The company currently operates 10 digestion sites in the United States and uses tracking systems to help understand why certain foods end up going to waste, Begin adds.

Deployment of anaerobic digesters is not cheap: a full-scale installation can cost tens or hundreds of millions of dollars. Designing new plants can also be time consuming, as most are tailored to particular processing tasks. An on-site facility for an ice cream factory may look different than one that can accept everything from grocery scraps like expired frozen pizzas and old apples to used cooking oils from restaurants, McKiernan says.

According to a 2014 report from US federal agencies, more than 11,000 additional sites in the United States are ripe for the deployment of anaerobic digesters, from wastewater treatment facilities to food waste sites. If all of these facilities were built, they could produce enough energy to power 3 million homes. The American Biogas Council, an industry trade group, puts the number of sites at 15,000, which would require about $45 billion for total construction.

It won’t be cheap and it won’t be fast, but anaerobic digesters could be a major destination for food waste in the future, helping to turn one person’s table scraps into energy for another.