The Qantas Group has chosen the General Electric (GE) GEnx engine to power its Boeing 787 fleet of up to 115 aircraft at the end of an eight-month evaluation process.

The initial order for 45 aircraft ship sets was valued at A$2 billion (US$1.58 billion) in capital and maintenance costs over the life of the engines.

"The GEnx was chosen because of its superior performance and environmental impact for the type of operation the group aircraft will perform," said chief financial officer of Qantas, Peter Gregg, in a company statement.

"The GEnx is 20 per cent more fuel efficient, produces around 20 per cent less carbon dioxide and 40 per cent less nitrous oxide than the engines on our B767 aircraft, and operates with a 50 per cent smaller noise footprint."