The core of the process is Acrion Technologies’ CO₂ Wash—also being used in a prototype LFG project with Mack Trucks. (Earlier post.) FirmGreen is a licensee of the Acrion process.

Landfill gas is a natural product of the biological decomposition of organic waste. The resulting gas has a variety of chemical components, but at most sites the two principal components are methane (CH₄) and CO₂, with much smaller amounts of hydrogen sulfides (H₂S), inerts and volatile organic compounds (VOCs).

A big problem with LFG projects is the presence of trace components. Typical LFG contains heavy hydrocarbons (both aliphatic and aromatics such as benzene) as well as numerous chlorinated hydrocarbons. These trace compounds are in some cases toxic or hazardous and also cause rapid failure or engine and turbine components. There are now federal statutes which cover landfill emissions.

Acrion’s process removes contaminants from LFG using liquid carbon dioxide obtained directly from the LFG, and produces a stream of contaminant-free methane and CO₂.

Contaminants are concentrated in a separate small stream of CO₂ for incineration in the landfill flare.

The contaminant-free methane and CO₂ stream can be used as medium BTU fuel gas, as a hydrogen source for the fuel cell or as feedstock for methanol synthesis. Further processing can separate CO₂ from methane to produce pipeline methane or transportation fuel (compressed or liquefied), and liquid CO₂.

(Brookhaven National Laboratory has signed a contract with Acrion to develop a process to produce marketable LNG and liquid CO₂ from landfill gas.)

FGE has big plans for the GEC with the Acrion process. The planned LFG processing facilities will:

• Generate up to 820 kW of electricity using Ingersoll Rand Micro-turbine technology.

• Produce Compressed Natural Gas (CNG) for SWACO’s landfill vehicles and local school buses.

• Produce up to 6 million gallons of methanol per year for sale to Mitsubishi Gas Chemical.

• Produce up to 75 tons per day of 99.9% pure liquid CO₂.

• Use LFG-derived methanol to produce up to 10,000,000 gallons of B100 biodiesel in conjunction with a sister biodiesel plant to be built.

• Produce Hydrogen gas using Pressure Swing Absorption technology for experimental fuel cell technology development with Ohio State University.

Resources:

• Analytical Results from Acrion CO₂ Wash Demonstration