Jeff St. John 07 17 09, 10:05 AM

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First of Its Kind Onion Juice-Methane-Fuel Cell Project Underway

Gills Onions has come up with a clever way to dispose of its daily 300,000-pound load of onion waste – turn it into methane, and use the gas to power fuel cells that can cover the plant's baseload electrical needs.

That's the gist of the $9.5 million project unveiled Friday at the Oxnard, Calif.-based onion processing plant.

The savings of $400,000 a year from deferred waste hauling, plus about $700,000 a year in deferred electricity costs – not to mention a $2.7 million self-generation incentive check from Southern California Gas Co. – should pay back the investment in less than five years, said Steve Gill, co-owner of the business.

The first step comes in taking the onion tops and skins normally thrown away at the plant and squeezing the juice from them, he said. That juice is fed into an anaerobic digester made by Biothane, a wastewater treatment company with offices in Moscow, the Netherlands, Indonesia and Camden, N.J., he said.

Anaerobic digesters are used by a number of agricultural plants to generate gas from waste like livestock manure. Companies like Microgy are installing them at dairy farms and other livestock operations (see Green Light post).

At Gills Onions, the resulting methane has a lot of sulfur in it – part of what makes onions smell – and that's stripped out before being fed into two 300-kilowatt fuel cells made by FuelCell Energy (NSDQ: FCEL), he said.

Using fuel cells instead of burning the methane lowers the greenhouse-gas emissions of the project. Added to the emissions avoided by not trucking away the waste that yields a 30,000 ton-per year reduction in the plant's carbon emissions, he said.

Southern California Gas – part of Sempra Energy, which also owns San Diego Gas & Electric Co. – is working on more waste-to-energy projects, including one with a "major waste hauler" and another involving treating wastewater and yielding "pipeline-quality" natural gas, said Hal Snyder, vice president of customer solutions at the utility.