When it comes to disposing of kitchen food waste, nothing beats good, old-fashioned composting. But if you haven’t made the leap yet, there may be another way to prevent your food scraps from ending up in landfills—where it pollutes the environment with methane gas, a more powerful greenhouse gas than carbon dioxide. In fact, you may already be using it. It’s your garbage disposal, or "food waste disposer," as the industry is calling them these days.
If, and this is a big if, the plant where your wastewater is treated converts waste into biogas, then your banana peels and potato skins will be used to create renewable energy and fertilizer products. If not, the solids are typically hauled away to a landfill or burned.
Here’s how it works: Your garbage disposal churns food scraps into a liquid slurry that moves through the sewer system to the treatment plant. There, it's broken down by bacteria through a process called anaerobic digestion, which produces biogas and biosolids. The biogas is captured to power the plant itself and sometimes even sold to the grid or used to fuel other things, like electric cars. The biosolids can be converted into fertilizer.
This technology isn’t new; Assyrians used it to heat their baths in the 10th century B.C., and 43 percent of the wastewater treatment plants in the United States are currently using anaerobic digestion in some way, according to biogasdata.org. Only 104 of those plants, however, use it to generate energy, which means the potential to grow this source of renewable energy is significant.
Here’s what the Water Environment Research Foundation had to say about the potential of biogas in a 2012 report:
“…renewable energy from biogas has the potential to supply an additional 200 – 400 MW of power that can be used on site at wastewater treatment facilities (WWTFs) or distributed back into the electric grid. Since about 4 percent of the electricity used in the United States moves and treats water and wastewater according to the Electric Power Research Institute (EPRI) (2002), the ability for WWTFs to generate power to offset their own demands or provide additional power to the grid is critical to reducing energy consumption.”
The report goes on to lay out the barriers to energy production, which include not enough return on investment, lack of capital, lack of interest from communities and utilities, difficulties with regulations and permits.
InSinkErator, a company that makes kitchen garbage disposals, has taken notice of the movement to reduce and deal with the overwhelming amount of food waste we produce in the U.S. and recently started marketing the green qualities of its products. Last year the company partnered with the city of Philadelphia to launch Clean Kitchen, Green Community, an initiative that installed disposals in 200 homes, provided incentive for other residents to buy them and provided education on how and why to use them.
While it seems that we have a ways to go until all our wastewater and pulverized food scraps are used to their full potential, the technology is there to make it happen. Take a few minutes to find out how your local wastewater treatment plant operates (here’s a partial list of plants using anaerobic digestion). If it’s making renewable energy, you can feel better about sending your scraps down the drain. If not, ask them why they aren’t. Sustainable America has a goal of cutting food waste in half by 2035, and this is one solution that will help make it happen.
This month, we're challenging the GOOD community to host a dinner party and cook a meal that contains fewer ingredients than the number of people on the guest list. Throughout March, we'll share ideas and resources for being more conscious about our food and food systems. Join the conversation at good.is/food and on Twitter at #chewonit.
Photo via (cc) Flickr user Watt Dabney