Landfill Gas to Ethanol

by Gary C. Young (Bio-Thermal-Energy Inc./Ethanol Producer Magazine) Mixed with steam, run through a reformer and fermented, landfill gas proves an economic and environmentally beneficial feedstock for ethanol production. And each LFG project is a source of green energy that can last for more than two decades.

A patented technology to convert landfill gas to ethanol has been garnering attention, most notably from the City of Cedar Rapids, Iowa. Plans are in the works to contract an independent engineering firm to conduct a technical, economic feasibility study for the technology at one of the city’s landfill sites.

The process was developed and patented by Bio-Thermal-Energy Inc. of Cedar Rapids, specifically to improve economics and reduce environmental impacts of landfills. Studies suggest the new process generates a net annual revenue, without a subsidy, and reduces carbon emissions from the landfill by more than 50%.

The Process
In short, B-T-E’s process combines landfill gas and steam in a reformer. The syngas produced, composed of carbon monoxide and hydrogen, goes into a fermenter. The result is ethanol.

Landfill gas, typically 50% methane and 50% carbon dioxide with some impurities, is cleaned up before entering the catalytic reformer with steam for conversion to syngas. After syngas cleanup, the syngas is fermented to ethanol using an existing commercial process similar to corn ethanol fermentation. A carbon balance about the entire process from landfill gas to ethanol indicates that about 56.9% of the carbon is contained in the finished product—ethanol. That’s 56.9% of the carbon from the landfill gas not emitted to the atmosphere.

In addition, leachate from the landfill can create additional landfill gas for production of more ethanol. Leachate is the liquid that exists in landfills, formed when rainwater infiltrates and percolates through the degrading waste. Recycling the leachate reduces the need to truck it to a waste treatment plant for processing and final disposal of solids to a landfill.

The landfill gas-to-ethanol process also provides funds for maintaining the landfill as required by regulatory agencies even after closing of the landfill operations. Landfill gas is produced, typically, for more than 20 years after a landfill is closed. READ MORE