Next Wednesday the protesters will set off from Hobart and spend two weeks winding their way up the east coast to Bowen, where coal dug from the Sunshine State is shipped across the globe.

The former Greens leader compared the anti-Adani movement to a nationwide action he led against the Franklin Dam in Tasmania in the 1980s - a battle eventually won by conservationists.

"This is the biggest environmental, heritage, indigenous and lifestyle issue I have seen come along in decades in Australia," he said.

"It's galvanising people everywhere."

Convoy numbers are expected to swell as it snakes its way up the east coast of Australia, holding protest rallies in major centres along the way.

The convoy is expected to arrive at the Carmichael mine site in the Galilee Basin on April 28.

Mr Brown said the convoy had two main aims.

"The first is to save the Great Barrier Reef from destruction due to the burning of the massive coal deposit Gautam Adani wants to exploit.

"The second is to bring hundreds of visitors on a tour which will leave small businesses better off all along the way."

Mr Brown said the federal Environment Minister Melissa Price gave go-ahead on the Adani mine "without integrity, sincerity or responsibility to Earth's future".

Australian Associated Press