The Eden Project's managers want it to become energy self-sufficient
The Eden Project in Cornwall has flown a large helium balloon over 400ft (121m) into the air to demonstrate how tall a proposed wind turbine would be.
The ecological tourist attraction wants to install the turbine in order to become energy self-sufficient.
But it has met fierce local opposition from residents who said the turbine was too big and vowed to oppose the plan.
In October the Eden Project put the project on hold for a month to allow locals to study the details.
The two megawatt turbine would cost £3m to build and would be twice the height of Nelson's Column.
Dave Rowe, from Eden, said the attraction had a responsibility to promote renewable energy.
But Andrew Dean, from the nearby village of Trethgurthy, said: "I was pro the turbine before I saw the balloon.
"Wind turbines usually look graceful, but the height of this is horrendous.
"It will overpower the whole landscape."