Landfills

How It Works

Landfill gas is produced naturally as organic waste decomposes in landfills. It is composed of methane, carbon dioxide, and small amounts of non-methane organic compounds. As an important and growing application within the world's power generation mix, landfill-gas-to-energy systems collect, process, and treat this gas for use in generating electricity. Two common approaches to landfill gas collection include vertical well extraction and horizontal collectors or trenches.

Municipalities generally use blowers or vacuums to direct the gas from a collection site through a network of pipes to a central facility. At most developed municipal solid-waste landfills, the methane and carbon dioxide are destroyed in a gas collection and control system or utility flare. The sustainable alternative is to divert the landfill gas from the flare to be used in electricity-producing Cat generators.

The diverted fuel is dried and sometimes refined to remove impurities such as:

• Sulfur
• Halides
• Siloxanes (Silica)

After fuel treatment, the methane is introduced into a Cat gas generator as fuel. These generators are specifically designed for operation at landfills with:

• A crankcase ventilation pump to eject potentially acidic blow-by gases
• Specially designed aftercooler cores, cylinder heads, main bearings, and connecting rod bearings that are hardened against corrosive elements
• Differentiated cooling systems to operate at elevated jacket water temperatures to prevent condensation of contaminants

Cat switchgear with PLC-based controls is supplied to parallel the generators to the local electrical grid to export renewable power at a premium to the local electric utility.