TV botanist David Bellamy has led around 300 protesters in a walk to the summit of a south Wales mountain in a campaign against wind turbine plans.
David Bellamy is an opponent of many wind farm projects
The group, Save Our Common Mountain Environment (Socme), organised the two-mile march on Mynydd-y-Gwair, between the Amman Valley and Pontardawe.
Mr Bellamy says he is unconvinced by the environmental case for wind power.
Organisers claim the Welsh assembly government considers the area suitable for "industrial-size" wind turbines.
Many local farmers joined the protest because they have grazing rights on the land.
A Socme statement said: "Mid Wales is being destroyed by misguided politicians and developers who use the excuse that wind turbines are needed in the name of global warming".
A spokesperson for the Welsh Assembly Government said that no proposal to build wind turbines at the Mynydd-y-Gwair site had been received.
The assembly wants to see 10% of electricity generated in Wales to come from renewable sources.
It is not the first time that Mr Bellamy has joined protests against windfarms - he has supported campaigns in Lancashire, County Durham, Cumbria and Kent.
He claims turbines are inefficient and expensive sources of energy.
"If we use wind, the cost of power is going to go up and up and up, as it has in Germany, as it has in Denmark, as it has in America," he said.
He also said that windfarms "ruined landscapes".
"They are not green, they chop up birds, they chop up bats," he said.
However, Alison Hill from the British Wind Energy Association, said attempts to limit the problems of the turbines were ongoing.
Government ministers are keen to build more wind turbines
"Wind turbines are tall rotating structures and can therefore pose a threat to birds - that is why we work with RSPB at the earliest stage of development.
"We don't arbitrarily come along and stick turbines up on hills where people don't want them.
"There is a planning process and part of that process is consultation with local communities."
She said wind energy was a vital element to backing up the UK's electricity system.
"We are losing conventional generation technologies, either through emission regulations from Europe, or through, for example, rising gas prices.
"What will we use to replace them? Wind can be part of the solution."
Windfarms have become a controversial issue across Wales in recent years.
In July, a large off-shore windfarm at Scarweather Sands off Porthcawl south Wales was approved by the Welsh assembly following a public inquiry.