Green Energy: Landfill Gas Capture and Utilization
Green Energy is working with Dubai
Municipality to
implement the first landfill gas flaring project in the United Arab Emirates. At the Al Qusais
landfill, the largest landfill in Dubai, Green Energy replaced the existing passive venting system
with a landfill gas capture plant. The plant collects gas from wells in the landfill and flares it
to remove methane, and the captured gas generates power for the system. The plant captures and
flares up to 6000 normal cubic meters (Nm3) of landfill gas per hour with a methane
content of
approximately 55 to 58 percent.
The Gas Collection System
The gas collection system installed at the Al Qusais landfill consists of both horizontal and vertical wells. The gas collection system utilizes gas trenches with a defined gradient from the center of the landfill towards the sides. Vertical gas wells connect to gas trenches. Green Energy implemented the collection system underground to allow movement of waste-dumping machinery on the surface of the landfill.
Diagram showing the Gas Collection System at the Al Qusais landfill.
The Compact Degassing Plant
The pipes used in the gas collection system connect groups of gas wells to manifolds. The manifolds are connected to a main pipe and then to the main header pipe, which delivers the gas from the collection system to the flare. The system operates at pressure slightly lower than atmospheric as blowers draw the gas from the wells through the collection system and delivers it to the flare, which “degasses” or safely removes the methane generated from the landfill.
Diagram showing the Gas Collection System at the Al Qusais landfill.
Power Generation
Currently, the gas capture system installed at the landfill can generate 1 megawatt (MW) of power. The energy generated powers the on-site blowers and the flares for the gas capture system. Green Energy plans to expand their project to be able to generate 13.5 MW of power.
Emissions Reductions
Green Energy’s measuring, reporting, and verifying protocol is Clean Development Mechanism (CDM) compliant and the amount of gas collected is monitored by compensated flow meters on a minute by minute basis. Green Energy collates the data on a monthly basis and aggregates the data to derive the annual figure. Green Energy estimates that the annual emission reductions from their landfill gas capture project are about 300,000 tonnes of carbon dioxide equivalent (TCo2e).