Gunfleet Sands test site for 6MW wind farm turbines
New more powerful wind turbines are being tested on a site off the Essex coast.
The two six megawatt (MW) turbines sit next to the existing 3.6MW turbines at Gunfleet Sands, off Harwich.
Made by Siemens and installed by Dong Energy, the new turbines are specially designed for off-shore use.
The Department of Energy and Climate Change says they're more cost effective and efficient than the turbines currently used.
Each of the turbines is twice the height of Elizabeth Tower, home to Big Ben in the Palace of Westminster.
Greg Barker, Minister for Energy and Climate Change Minister, said the Government's energy plans had "an important role for offshore wind".
"By building these turbines offshore you can go much larger and they become much more efficient," he said.
Benj Sykes, Dong Energy Wind Power's UK country manager, said the new turbines were an "important milestone" for the firm.
Henrik Stiesdal, chief technology officer at Siemens Wind Power said: "Gunfleet Sands III is a very important project for us to bring the 6 megawatt direct drive turbine out to the offshore environment.
"The two prototypes have been pre-tested here under hardest conditions and we have made tremendous progress with the experiences gained by that.
"Now we will test the turbines under long-term conditions of normal energy production."
Gunfleet Sands is a 172MW wind farm.