The Jetty Boil Off Gas Recovery (JBOG) project will recover the gas that otherwise "flares" during LNG loading at six LNG berths in the port, project operator Qatargas said in a statement.
The project will save 1.6 million tonnes of CO2, Qatargas said.
Operated by Qatargas on behalf of Qatar Petroleum and RasGas Company, JBOG will collect 29 billion standard cubic feet of gas annually, which is enough to produce 750MW of power, Qatargas said.
Qatargas chairman Saad Sherida Al-Kaabi said: "The JBOG Project demonstrates the commitment of the State of Qatar to balance industrial development with care for the environment and reinforces our pioneering and leadership role in the energy industry."
"We don't have an expectation of an economic return from the project, but we will benefit from the recovered gas," Saad Sherida al-Kaabi, Qatar Petroleum chief executive said at an inauguration ceremony for the project, MenaFM reported.
Doha-based Peter Blackmore of Pinsent Masons, the law firm behind Out-Law.com, said: "The project aligns with Qatar's national development strategy 2011-2016, which sets ambitious environmental targets including for gas flaring levels to be halved from 2008 levels."
JBOG uses the largest low pressure compressors in the world, supplied by General Electric (GE), Qatargas said.
Work on the project began in October 2014, and gas has since been recovered from over 500 ships.