Landfill gas, canola and biodiesel: working towards a sustainable system

Snohomish County in western Washington State began converting its vehicle fleet to a blend of biodiesel in 2005. As prices for biodiesel rose due to increased demand for this cleaner-burning fuel, Snohomish County looked to its farmers to “grow” this fuel locally. Suitable oil seed crops for biodiesel feedstock include canola, mustard and camelina. The residue, or meal, has high value as an animal feed. County farmers began with 52 acres of canola and mustard crops in 2006, increasing to 300 acres and 700 tons in 2009.

The team consisted of Snohomish County Public Works, engineering firms (URS Corporation and Parametrix), Washington State University Extension, Wolfkill Feed and Fertilizer (local fertilizer company) and various equipment suppliers, It was necessary to develop local infrastructure for the canola project because canola is not a traditional crop in Snohomish County. To reduce the project’s cost and environmental footprint, the County tapped the methane content in landfill gas from the closed Cathcart Landfill south of the City of Snohomish and about 35 miles north of Seattle as the energy source for the seed dryer, in lieu of propane or natural gas. The canola processing facility is located at the landfill site, adjacent to the existing landfill gas blowers and flares. Project benefits include:

• Revitalization of the local agricultural community, increasing the County’s economic diversity, a key goal of County government
• Addition of an excellent rotational, low tillage crop that can also convert pasture into row crops
• County ownership of a commercial facility suitable for drying other grains and crushing other seeds for oil production
• A central location of the dryer and crusher that reduces transportation to processing and to the refinery that converts the canola oil into biodiesel
• A beneficial use of a declining landfill gas stream that still contributes to reaching sustainability in vehicle fuel

This article discusses the challenges of the design and equipment procurement process, permitting, construction and startup, operational results and lessons learned.

Project Goals
The goals of this project are to:

• Support the use of biodiesel in Snohomish County’s vehicle fleet
• Support local agriculture
• Beneficially use landfill gas, an energy source previously wasted through flaring
• Create community resiliency by reducing dependence on petroleum-based fuels and shortening supply lines

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