The windfarm has not provoked strong opposition
Electricity generation at the UK's first major offshore windfarm begins on Friday off the north Wales coast at Prestatyn.
When fully operational, the North Hoyle windfarm will be capable of producing enough power for 50,000 homes.
Thirty wind turbines standing more than 40m high have been built four to five miles off the coast.
There has been surprisingly little opposition to the project compared with the experience of windfarms in other parts.
Electricity from two turbines will enter the National Grid, with the rest being commissioned over the next few months.
Project operators National Wind Power have invested £70m in the project, and the switch-on represents an important day for them.
The government is aiming for more schemes like this one to take the strain of generating electricity for the UK.
It has a target of producing 10% of the UK's energy from renewable sources by 2010.
Now eco-minded residents can pay their electricity bills direct to a company which has set up a joint venture with environmental campaign group Greenpeace.
The assembly economic development minister, Andrew Davies, said: This is a very exciting time for the renewable energy sector in Wales.
"The start of electricity generation at North Hoyle marks the beginning of a serious, mainstream approach to renewable power development offshore and provides a significant contribution to our renewable energy targets
"We have considerable natural resources in Wales, both on land and at sea.
"I very much hope that we can develop indigenous, home-grown industries to serve this growing sector and maximise the benefits for the Welsh economy and environment.
Speaking earlier this year, Stephen Tindale from Greenpeace commented: "This pioneering windfarm will lead the way towards...bigger developments in UK waters that we so urgently need to help tackle global warming"
"The first turbine installed at North Hoyle represents a crucial milestone on the road to clean energy in the UK."
National Windpower also has planning consent to build a second offshore windfarm at Rhyl Flats near Abergele.
A spokeswoman said they are still discussing how best to take the project forward.