Enough energy will be produced by the turbines to supply every domestic property on the Lizard
The current turbines at Goonhilly on the Lizard are nearing the end of their 20-year life cycle.
Originally installed in 1993, they are now to be replaced.
Figures from the current site said that the old turbines generated electricity on 98% of days during their time there.
The new turbines are rated five times as powerful. All electricity will go into the local wires which serve the Lizard, Helston and the surrounding areas.
The old machines have been running since 1993
It is estimated that there have been a total of 240 million revolutions per turbine and more than 3 billion revolutions for the whole wind farm since it became operational.
As well as supplying electricity, Goonhilly wind farm is also used as a teaching resource by the University of Exeter in Penryn, Mullion School and Helston School.
The University of Exeter offers BSc and MEng Honours Degrees in Renewable Energy. This provides graduates for the renewable energy industry worldwide.
Read more about the changes that are due to take place here with our questions and answers page.
Why do they need replacing?
The old machines have been running since 1993. The six new turbines will use the latest turbine technology, replacing the current 14 outdated models and trebling the annual output from less than half the number of machines. The installation of the new more efficient turbines will deliver a carbon-free future for homes on the Lizard.
Why do they have to be twice the height of the old turbines?
The existing wind turbines, while well maintained, have been superseded by more efficient modern designs.
Although the top of the new blades will be a little over twice the height of the existing ones, they will capture three times more energy.
The site therefore will have less than half the number of turbines, but its output will treble.
The new turbines will be fewer, slower, bigger physically, and much bigger in terms of production. Only six units will be installed, instead of the existing 14.
They will turn much more slowly, so the blades will look almost leisurely, but they'll be working hard.
How high will the turbines reach?
From the base to the tip of the blade when it is rotating - the turbines will reach 107 metres.
When will electricity be produced by the new turbines?
Work on the repower began in March and is expected to be completed by the end of September, with the first electricity from the new turbines beginning to power local homes then. This will be the most powerful wind farm in Cornwall and the South West.
How much energy will the new turbines produce?
Using an example of a house with four energy saving 11W light bulbs, on for six hours a day, the current wind farm could light over 90,000 households.
A wind turbine against a sunset sky in Scotland
The projected repower with the new turbines will increase this to 300,000 households.
The current output from Goonhilly is approximately 9000 megawatt hours (MWh) with the repower taking it to almost 30,000 MWh.
One MWH is equivalent to one thousand kilowatt hours, or 'electrical units'.
It is estimated that the carbon free electricity from Goonhilly will save over 12,000 tonnes of carbon dioxide (CO2) per annum against a current estimate of nearly 4,000 tonnes of CO2.
(If converted into lorry loads, that means currently saving 20,000 lorry loads of CO2 per annum, and 70,000 lorries loads of saved CO2 following the repower.)
Where will this energy go? Will it be distributed within Cornwall?
The six new turbines should be able to provide the domestic energy needs of the whole of the Lizard Peninsula. This is carbon-free electricity for a whole peninsula.
The amount of electricity produced will be so great that it cannot be delivered to the surrounding area through the existing electrical connection.
Because of this, Cornwall Light & Power have paid Western Power Distribution (which owns all the local wires) to put in a new connection.
This supports the local system and cost almost £1m. It will serve Mullion and the Lizard for 20 years.
The Lizard peninsula is a beautiful place which enjoys clean air and little or no pollution. One of its natural resources is the clean air that passes across it.
What will happen to the old turbines? Can they be recycled?
The old turbines will be taken down and then sold on. People will come and buy them, refurbish them and use them to generate electricity in appropriate places.
How much would the old ones cost to buy?
It is expected that the old turbines will fetch in the region of £30,000 to buy.