Self-powered onion factory wins ACEC award

The Gills Onions’ advanced energy recovery system project was led by Omaha, Nebraska-based HDR Engineering’s water business group in Irvine in Southern California.

Gills Onions, the largest fresh-cut onion processor in the US, faced a growing problem with disposal of waste from their onion processing plant. The HDR/Gills Onions team turned this problem into an advantage by developing a $9.5m (£6.4m) facility that converts 200,000lb of daily onion waste (peels, stems and tops) into biogas that can be used as fuel.

In the facility, juice is extracted from the waste and treated in an anaerobic digestion reactor to produce methane-rich biogas. The biogas is then treated to remove moisture and sulphur and used to power two 300KW fuel cells that supply 60 per cent of the onion processor’s annual power needs.

The combination of the energy produced, cost savings generated and grant funding will result in a full payback in less than six years, according to Gills.