Food is a big part of why Thanksgiving is my family’s favorite holiday. Over the years, we have tried to eat sensibly and sustainably, and to waste less food. But on the Monday after Thanksgiving, I suspect we are not alone as we contemplate the wilted salad, the wan sweet potatoes, and the last of the now not-so-attractive leftover turkey. Indeed, one recent study by NRDC estimated that Americans throw away 40% of their food.
In the last few years, declining capacities at conventional solid waste disposal facilities, combined with the realization that there are more beneficial things to do with food waste and other organics than to throw them in a landfill or burn them have led to partial food or organic waste bans in California, Connecticut, Massachusetts, Vermont, as well as in cities such as Seattle, San Francisco, and New York.
Of course, these ambitious waste segregation programs require that there be an alternative location to reuse or process these materials. Historically, organics have been transformed into compost or animal feed. Unfortunately, the volume of the waste stream is far in excess of what existing, generally small composting facilities can handle. Larger facilities that might be able to increase capacity are generally located far from urban and suburban centers that generate the waste. Many regulators have recognized the need to create an infrastructure to handle this material but a more comprehensive national program is needed if we are really going to stop throwing our food into landfills.
One of the most promising technologies to manage the large amount of organic waste generated near city centers is anaerobic digestion (“AD”). AD systems use anaerobic bacteria to break down organic matter into methane and carbon dioxide. The resulting methane can generate energy in place of traditional fossil fuels. A large-scale system might generate as much as 8-10 MW of electricity (enough to power 8-10,000 homes), while diverting thousands of tons of organics from landfills. And as a bonus, the residual materials can be used as compost or soil amendments. AD systems are well established at wastewater treatment plants and are emerging at certain large agricultural operations.
But there have not been many large scale AD systems designed to handle the anticipated flood of organics that will soon be separated from the general waste stream. Part of the problem may be one of raw material supply – a single large AD system may need hundreds of thousands of tons of segregated organic materials annually. The waste bans may help develop a reliable supply. Siting of these facilities presents other challenges. Some states, most notably Massachusetts have amended regulations to make it easier (though certainly not “easy”) to permit these facilities, at least on a state level. Hopefully other regulators will follow suit, allowing market forces to coalesce and expand what is now a nascent industry. Otherwise the organic material diverted from the solid waste stream by well-intentioned laws and rules will pile up in unpleasant ways.