Caterpillar 3520 Landfill Gas Engine
NTSWA has been utilizing landfill gas to operate a CAT engine for over 12 years. On the surface, a simple enough concept, but this project continues to evolve producing results from the destruction of landfill gases such as the real time sale of electricity, waste heat recovery, the production of edible crops through controlled environmental agriculture and the future off setting of carbon credits.
The system begins with a series of 4” and 6” HDPE wells placed on a minimum of 200 feet radius throughout the landfill. These wells are equipped with dewatering pumps. Removing the water from the wells makes gas migration easier. The wells are connected to a perimeter gas conveyance system that is controlled by a series of blowers. Putting negative pressure on the well field pulls the gas to the CAT 3520 engine. The engine then consumes the methane which creates up to 1600 kWh of electricity. The majority of this electricity is sold to the grid. This process also creates a tremendous amount of heat from its cooling water jacket. This supplies heat to the on-site leachate treatment facility, 14,400 square foot hydroponic greenhouse and 9,600 square foot truck garage. The heat from the exhaust is also captured and utilized to run NTSWA’s Thermal Heat Recovery Project. In 2012, the CAT 3520 engine had a run efficiency of 96.4%. It was only shut down for necessary maintenance.