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Originally published in Interiors & Sources

10/01/2013

Food Waste to Power Grocery Store

Biogas released from food scraps will supply 20% of energy demands each year.

 
  • /Portals/1/images/Magazines/2013/1013/B_1013_Sustainability2.jpg

    This system uses anaerobic digestion to produce methane from expired foods, rerouting 55,000 tons of organic material from the landfill each year.
    Credit: KROGER

  • /Portals/1/images/Magazines/2013/1013/B_1013_Sustainability3.jpg

    This system uses anaerobic digestion to produce methane from expired foods, rerouting 55,000 tons of organic material from the landfill each year.
    Credit: KROGER

Sour milk, rancid meat, stale bread, rotten fruit – whereas most groceries are forced to send expired food to the landfill, Kroger is turning this organic waste into energy.

The grocery chain recently installed an anaerobic conversion system that will help power a 650,000-square-foot distribution center in Compton, CA. The renewable energy will offset more than 20% of the building’s energy demand annually, and 55,000 tons of organic waste that cannot be sold or donated are diverted from the landfill.

The technology can handle over 300,000 pounds of waste on a daily basis. The process is carried out in an enclosed, oxygen-free environment.

Food scraps – including plastic, glass, and cardboard from packaging – are sent through a grinder. A pulping machine then filters the resulting slurry for inorganic material and the mulch is routed to a multi-story staging tank.

From there, bacteria break down the refuse, thereby releasing methane gas. The collected gas powers several microturbines and boilers, which provide heat and steam for an adjacent creamery.

Excess liquids are purified and released into the sewer while leftover mulch is redistributed on farms as a fertilizer.

By diverting the equivalent of 150 tons of food waste per day, area truck trips are reduced by more than 500,000 miles each year.

 

 

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