Every single day, enormous amounts of energy is converted by means of power plants, solar panels, wind turbines, and more, to generate enough electricity for our technologically dependent world. But there’s a new, unexpected player coming to the field. That player is FOOD WASTE.
How could food waste be used to generate energy? Every single day, businesses that are centered around foodstuffs end up throwing out a large majority of the food that they produce. In fact, over 40% of the food produced each year in the U.S. will end up being labeled as trash and is historically thrown to the side. With the fairly new processes of aerobic and anaerobic digestion, this food waste can become more useful than ever.
Kroger Supermarkets is one of the first companies to utilize the process of anaerobic digestion to convert their food waste into energy. Their newly-built Kroger Recovery System located in Compton California was created to harvest energy from day-old bread and too-ripe bananas to generate enough electricity to power more than 2,000 homes in California over a year’s time. Now, of course the machine does not solely rely on stale bread and rotten bananas, instead, the anaerobic digester will process over 55,000 tons of organic waste per year (or 300,000 pounds a day), collected from their stores generating the 13 million kilowatt-hours that will power Kroger’s Compton distribution center for a year.
Upon arrival, the food will be churned in a large grinder until it is completely pulverized. Then, this substance will be introduced to a pulping machine, where hot wastewater is added, creating a thick, mucky substance. After this, the sludge is pushed into a large tank and then into an oxygen-free silo. Here, in this 2-million-gallon anaerobic environment, the sludge will be eaten away by bacteria, converting it into methane gas, known as biogas. This biogas is then filtered out of the silo to three turbine engines, located at the facility. The three turbines will then convert the biogas into usable energy, which is enough to offset the company’s energy demand by more than 20%.
The anaerobic process produces no pungent odors, as some may fear, and no methane is leaked out of the system and into the atmosphere. This system will also reduce area truck trips due to the fact that they no longer have to haul the 150 tons per day six times a day by diesel trucks traveling 500,000 miles a year to distant composting facilities.
Why anaerobic digestion? Kroger believes that this solution best addresses their business strategy – realizing the value of food waste. Instead of sending all of the unwanted food on trucks to be dumped into landfills or to distant compost facilities, this solution is an easy and effective method for creating clean energy. Building this facility to recycle their food waste also has the potential to save the company $110 million.
Amid high waste disposal costs and uncertain energy prices, anaerobic digesters have gained favor. The success of this one highly-publicized facility shows promise that more facilities like this will be in our future.