When Life Gives You Onion Waste … Repurpose it!


There’s a lot of buzz about “sustainability,” but a recent panel discussion on January 23 (the latest event in the lecture series sponsored by Cal Poly’s CAFESCenter for Sustainability) proved that it’s here to stay – not just because it’s better for the planet, but because it can also offer businesses some significant savings to their bottom line. Indeed, one of the three tenets of sustainability is based on economic viability (the other two are the environment and social equity). If a practice is not profitable, ultimately it is not sustainable in the market place.

Jocelyn Gretz, the Sustainable Agriculture Program Manager for Rio Farms/Gill’s Onions, was one of the presenters at “Paths to Sustainability in Food and Agriculture.” She discussed several ways that these family-owned and – operated companies are introducing sustainable practices, but among the most striking had to do with truck tires and onion juice.

Gill’s Onions, established in 1983 and based in Oxnard, CA, is “one of the largest processors of fresh-cut onions in the country.” In an effort to improve fuel efficiency in its fleet of 15 freight liners, they replaced the standard, side-by-side dual wheels with heavy duty super single tires. This action paired with upgrades to their new diesel fuel injection engines, lighter weight aluminum trailers and other improvements in their fleet has decreased enough drag for the company to realize an annual 90,000 gallon savings on their diesel usage!

Another effort the company made towards sustainability involved some cutting edge technology. As anyone who has cut an onion knows, you have to cut off both ends and remove the outer skin before you get to the usable part. Now extrapolate that into an operation the size of Gill’s – that’s a whole lotta onion waste, 300,000 pounds a day, to be precise. However, by making a significant investment ($10.8 million) in their Waste to Energy project, Gill’s was quite literally able to turn trash to treasure.

Here’s a very, very, quick thumbnail sketch of how the Advanced Energy Recovery System (AERS) works … first, all the liquid is extracted from the onion waste, resulting in dry “onion cake” that can be used as cattle feed, and it turns out that it’s a fairly nutritious one at that. The leftover onion juice – or as Gretz called it, “OJ” – then goes into an anaerobic environment where bacteria digest it and creates enough biogas to supply 100% of the company’s baseline electricity needs. Who knew that when life gives you onion waste, you can make cattle feed and renewable electricity out of it?! For more information on Gill’s Sustainability efforts, visit http://www.gillsonions.com/sustainability, or contact Nikki Rodoni, Director of Sustainability, Gills Onions (NikkiRodoni@GillsOnions.com).

(Thanks to Jocelyn for her input to this post!)

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