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Kompogas-SLO digester pushes toward sustainable future on Central Coast

Posted at 9:13 AM, Mar 10, 2021
and last updated 2021-03-10 15:29:23-05

Sustainability and green energy are on the forefront at one San Luis Obispo business. Kompogas, an anaerobic digestion facility, has been converting organic waste into renewable energy and giving away organic compost to local farmers and everyday gardeners.

Creating power for about 600 homes per year from more than 72,000,000 pounds of your waste, Kompogas SLO is a zero-waste facility from start to finish.

“Waste is our energy. We do not discharge anything,” said Thomas Gratz, sales manager for Hitachi Zosen USA, the parent company of Kompogas. Gratz gave KSBY’s Neil Hebert a full tour of the facility that pumps out green energy to the Central Coast.

“The whole process is about reducing our carbon footprint, preserving our environment for future generations, by diverting organics out of landfills. Organics in landfills create methane gas, which is a 20x worse greenhouse gas than CO2 would be,” said Gratz.

Here’s how the process works: You put your organic waste like grass clippings, leaves, and kitchen scraps into your green bins and wait for garbage day. That waste is taken to the facility and dropped off. Contaminants like plastics and metals, among other materials, are then weeded out. The organic waste is shredded into smaller pieces, a magnet grabs any leftover metals, and then the waste is transported via conveyer belt to the anaerobic digester.

The anaerobic digester is a sealed, oxygen-free tank, used to create green energy in the form of biogas and compost over the course of 14 days.

“It’s a heated process at 131 degrees Fahrenheit, a 14-day process (to) take out all the volatile organics and convert into renewable energy in the form of biogas,” said Gratz. “(It’s) very similar to what’s going on in your stomach; that digester literally digests the organic waste and produces gas and energy out of it.”

600,000 gallons of organic material are inside the digester that never shuts off.

“Our oldest facility ran for 27 years without anyone going inside the vessel,” said Gratz.

20% of the product turns into gas that’s sold to PG&E and put on the power grid, and the rest is liquid or solid compost that’s either given to farmers or sold for commercial agriculture.

“This is actually the compost from the final treatment and screening step,” said Gratz with a hand full of compost. “This is what’s being supplied to farmers in the area as all organic and all-natural soil amendment. We don’t want to discharge and waste that and send it to a treatment facility; we actually give it away to farmers to displace fossil fuel fertilizers.”

Gratz says the entire process is like a life cycle.

“We have the plants that are using the compost, they become food. That food becomes discharged if we don’t eat it, and the digester will eat it and makes more compost and more energy to grow more food, so it’s a complete circle,” said Gratz.

But before you go and toss all your garbage into the green bins, there are a few things that shouldn’t be included.

“Treated lumber, clay pots, plastic wraps and things of that nature,” said Gratz on what to keep out of the bins. “What is okay is soiled food paper like a wrapper of something that’s not coated with plastic.”

Kompogas is holding an open house on April 10 from 10 a.m. to 2 p.m. for anyone who wants compost for their garden or field. Show up with bins or an empty truck bed, and Kompogas will load them up. Kompogas is located at 4300 Old Santa Fe Road in San Luis Obispo.