High Winds Wind Farm at Harlock Hill
The wind farm has two turbines, underground cabling to the sub-station, the sub-station itself, stoned tracks from the main entrance, crane hard standings and an underground cable, leaving site to feed into the National Grid at Ulverston.
The Enercon E70 turbines are German built by Enercon and are (each) rated at 2.3MW. The E70 is a popular machine and is especially useful at sites with high wind speeds. The rotor is three bladed and each fibreglass blade rotates clockwise. The length of the blade is 35.5m, the hub height is 64.0m making the height from ground to tip 99.5m. The rotor turns in the speed range 6.0-21.5 rpm and the rated power is produced at wind speeds of 15m/s (the equivalent of 33mph) and above.
ENERCON storm control – ENERCON wind turbines run with a special storm control feature. Storm control enables reduced wind turbine operation in the event of extremely high wind speeds, and prevents typical shutdowns which cause considerable yield losses.
The blade profile is like that of an aircraft wing and the pitch-the angle of attack to the wind- is variable according to the wind speed. The tips of the blades are turned up (like a modern aircraft wing) and reduce the air turbulence at the tip resulting in less noise.
There is a control system to achieve maximum output under all weather conditions. The turbine has yaw control, that is, internal machinery moves the rotor to face the wind direction according to an anemometer on the nacelle.
There is no gear-box: the rotating rotor shaft passes through the centre of an annular generator. This means that there is no noise produced compared with the arrangement with an intermediate gearbox, that there are few rotating components leading to reduced mechanical stress, operating and maintenance costs.
Generator and other Components
The nacelle complex is constructed from two cylindrical tapering steels towers, bolted to reinforced concrete foundations. The foundations are relatively wide and not very deep-think toy soldier bases.
The output voltage and frequency vary with the speed of the rotor. Additional equipment ensures that the output power is regulated according to the grid specification required. Within the turbine, a transformer increases the voltage from 400V to 11KV, which electricity flows to the on-site sub-station, where it is metered. Using the former underground Baywind cable, electricity passes to the Ulverston sub-station where it enters the Grid.
The turbine components were shipped to Barrow docks and the escorted to site using an improved route for abnormal loads. The route was widened and smoothed around bottle neck corners and, where necessary, the verges were widened and hardened. On site, new stoned tracks were laid for access to the turbine positions together with a crane hard standing area (where the coaches will park on the Open Day) and a separate rotor assembly platform. Rather than lift the rotor hub and then fit the blades one by one, the rotor was assembled on the ground and lifted in one piece by a very large crane.
In reality, the two turbines do not generate 4.6MW all the time. Over time, the actual output divided by the rated output expressed as a percentage is known as the capacity factor. High Winds expects the capacity factor to be around 30%. Only when the farm has been operating for a year will we know what the capacity factor is: and then it varies slightly from year to year…
The real output is sometimes expressed as the average electricity consumption per household. Using the most recent DECC figure (for 2014, 4115kWh), the assumed capacity factor of 31% the number of households served by the wind farm are 3,040.
The two turbines were energised on 18 May 2016.
The turbines will be maintained by Enercon through a long term Operation & Maintenance contract. This will include twice annual service and general breakdown cover.
Energy4All will monitor the wind turbines on a daily basis and report any issues to Enercon along with producing a monthly production report for the High Winds Board.
Power Purchase Agreement
High Winds has entered into a contract with Smartest Energy to sell the electricity and claim the Renewable Obligation Certificates (ROCs).