The $1.5 billion CopperString 2.0 proposal to build a privately owned electricity transmission line from Townsville to Mount Isa has received a major boost with a global infrastructure funder backing the project.

The 1100-kilometre high-voltage line  – which is being touted as the largest geographical expansion of the National Electricity Market in 20 years – is still relying on a major contribution from the $5 billion Northern Australia Infrastructure Facility to get across the line.