With anaerobic digestion, companies can reduce not only their waste, but also their carbon footprint while producing energy.
By Matt Alderton
If they’re allowed to grow on food that you intend to eat — think undercooked chicken, for example, or moldy bread — microorganisms can make you sick. If they’re allowed to grow on food that you intend to throw away, however, microorganisms can make your business more sustainable.
That’s thanks to a process known as anaerobic digestion.
As with composting, anaerobic digestion involves separating food scraps and letting nature turn them into something that’s useful instead of wasteful. In the case of composting, that’s compost, a nutrient-dense substance that looks like garden soil and can be used as a natural fertilizer for growing plants and crops. In the case of anaerobic digestion, however, nature’s byproduct is biogas, which consists mostly of methane — the primary component of natural gas.
“Biogas isn’t as pure as fossil natural gas, which comes from swamps that were buried under rock for millions of years, but it looks exactly the same and can be produced in a month instead of tens of millions of years,” said certified permaculture designer and teacher Ryan Cooper, Director of Circular Economy Solutions at Rubicon, a software company whose mission is to end waste. “Once you’ve produced biogas, you can burn it in a generator to create electricity, clean it and put it into a pipeline with natural gas or compress it and use as vehicle fuel.”
Because biogas is a clean and renewable resource, companies that produce their own biogas from food waste and use it for power, heat or transportation are reducing their dependence on fossil fuels and emitting fewer greenhouse gases. The result — a smaller carbon footprint — can score them major points with governments, customers and business partners who value environmentalism and sustainability.
“More and more municipalities, regulators, investors and consumers are demanding these types of business practices from companies,” continued Cooper, who says facilities managers who are interested in anaerobic digestion can do it onsite in a company-owned anaerobic digester — a closed system whose main component is a large, oxygen-free tank in which microorganisms can feed on food waste — or offsite, in which case a third-party supplier picks up your food scraps for processing at its own facility.
Because onsite anaerobic digestion requires investing in equipment and skilled personnel who can operate it, along with back-end infrastructure that’s needed to utilize the biogas that’s produced, most companies that engage in anaerobic digestion choose the latter. U.S. grocer Kroger, however, is among the companies that have chosen the former. In 2018, it installed a $9.5 million anaerobic digester at K.B. Specialty Foods, a manufacturing plant that the company owns and operates in Greensburg, Indiana.
“We invested in the digester because it improves our sustainability performance, supports better air quality and provides a cost savings to the company,” Erin Sharp, Kroger’s Group Vice President of Manufacturing, said in a statement. “Once the digester is operating at its optimal level, we project it will have the capability to produce nearly 30% of the plant’s electricity.”
U.S. Environmental Protection Agency: The EPA explains what anaerobic digestion is and how it works.
American Biogas Council: The American Biogas Council promotes the biogas industry and shares resources to help with biogas production and utilization.
Farm and Energy Initiative: The Farm and Energy Initiative explains the environmental and economic benefits of anaerobic digestion.