Landfill gas helps power Siouxland Ethanol plant

Web exclusive posted Sept. 11, 2008 at 1:08 p.m. CST

Jackson, Neb.-based Siouxland Ethanol LLC has used landfill gas piped over from the L.P. Gill landfill located a mile away since December, and at press time, U.S. Energy Services is assisting the landfill in selling six months worth of carbon credits.

The landfill gas is blended with natural gas in the thermal oxidizer to power the 50 MMgy ethanol plant production.

Not long after Siouxland Ethanol announced the intention to build an ethanol plant near the landfill, Leonard Gill, owner and operator of the landfill, approached the organizers with the idea to utilize landfill gas. "Without the sale of methane and carbon credits, a collection system was simply too expensive for a medium-scale operation such as ours," Gill said. Work to develop a project that would meet financial, technical and regulatory requirements began. Siouxland Ethanol started production in May 2007, and six months later began using the landfill gas.

U.S. Energy Services coordinated the qualification of the project as a "carbon offset provider" and is involved in managing Siouxland Ethanol's energy use. U.S. Energy Services monitors the ethanol plant's landfill gas usage, and dispatches just enough of higher priced pipeline gas to meet pipeline balancing rules. While this activity can be complex and challenging, according to Eric Todd, U.S. Energy Services account executive, "Our operational management capabilities allow us to efficiently track and balance natural gas requirements and provide maximum value to both L.P. Gill and Siouxland Ethanol by maximizing the landfill gas and minimizing the pipeline natural gas."

There were several potential hurdles that had to be addressed before the project could be implemented. L.P. Gill used their longtime environmental consultant, Steffen Engineering and Testing Inc., to determine that a reliable and economic collection and pipeline system could be installed.

For the ethanol plant, the critical issue was whether landfill gas could be used without causing operational problems. Ethanol process engineering firm ICM Inc. redesigned the plant's thermal oxidizer to allow lower British thermal units (Btu) landfill gas to be mixed with higher Btu pipeline gas that can be used simultaneously and in varying quantities. Fagen Inc. completed the construction and landfill gas started flowing to the ethanol plant in December 2007.

The plant thermal oxidizer/boiler is now operating with a mix of landfill gas and pipeline natural gas. As the flow of landfill gas changes, the flow of pipeline gas is automatically adjusted to meet the boiler needs. "By monitoring the landfill gas flow and Btu in real time, our boiler control system optimizes the landfill gas usage and compensates for the varying flow rates automatically," said Chuck Hofland, general manager for Siouxland Ethanol.