Greenpeace Australia Pacific chief executive officer David Ritter has used Twitter to throw his weight behind the Puma2Go campaign.
Mr Ritter was in the region on the weekend to present a talk at the Margaret River Readers and Writers Festival.
He has written three books including The Coal Truth, Contesting Native Title and The Native Title Market.
On the weekend Mr Ritter visited Dunsborough and tweeted he heard about plans to put a new petrol station in the heart of town.
“That would be insane-fossil fuels have no future. #puma2go.”
The City of Busselton and community action group Puma2Go have campaigned to try and stop a third petrol station from being built within 150 metres of each other in Dunsborough’s town centre.
Last week, the city advised it had run out of legal avenues to stop the development from going ahead.
The developers Puma Energy were able to bypass town planning laws by calling the development a convenience store rather than a petrol station.
In May, the Supreme Court dismissed a Southern Joint Development Assessment Panel appeal against a State Administrative Tribunal approval for the proposed development of fuel sales and a convenience store outlet.
Puma2Go representative Greg Milner said it was certainly heartening to have the backing of Greenpeace.
“But the developers and Puma have a tin ear,” he said.
“They're totally unresponsive to community concerns and the opposition of the City of Busselton, so we're not holding our collective breath.
“The only thing that matters to them is the money.”
Mr Milner said they would encourage and lobby all Dunsborough residents and visitors to boycott Puma.
“Any prospective franchisee should be nervous about the community turning its back on them, and going broke,” he said.
“After all, Dunsborough has plenty of options, we've already got two other petrol stations in town.”