How To Make Electricity From Waste Onion Juice

Onion juice can do more than just make us sob; it can also be used for electricity. Gills Onions, a California wholesale producer of sliced, diced, slivered and puréed onions, introduced a system today to turn its 300,000 pounds of daily agricultural waste into valuable energy.

The Advanced Energy Recovery System (AERS) is an anaerobic digester that turns shredded and pressed onion waste (aka onion juice) into biogas, which is then conditioned and turned into methane--the main component of natural gas. The gas goes into Fuel Cell Energy's 600 kilowatt fuel cell to be turned into power. Leftover onion waste--mostly pulp--is used as cattle feed.

In the past, all of Gills' onion waste was sent to decompose in fields. The method effectively returned the waste to the soil, but it also attracted insects. So Gills decided to invest $9.6 million in the first-of-its-kind AERS system. A pricey investment, to be sure, but Gills already received $2.7 million in incentives from Southern California Gas Company. The onion producer will also cut its power bills by $700,000 yearly and save $400,000 from not using manpower on spreading onions over fields. And then there are the environmental benefits; Gills will produce 35% to 40% of its electricity with the AERS system, cutting CO2 emissions by 30,000 tons each year.

Next up for Gills: exploring ways to recycle water left over after onion juice is recycled. SoCal Gas is picking up on Gills' AERS system, too, by looking at how methane produced at homes and dairies could be fed into the main gas pipeline. The technology is still primitive, but companies willing to invest upfront could ultimately reduce electricity costs and contribute to CO2 reductions.