Onshore wind turbines are a renewable energy source that harness the kinetic energy of moving air to generate electricity. The output depends on the strength of the wind, the size of the blades, their height above the ground, topography and the proximity of buildings.

Turbine blades are designed to rotate when they are hit by the wind. Typical turbines will start rotating at a wind speed of 3-5 meters per second, the equivalent of a gentle breeze. The rotation of the blades turns a shaft in the nacelle, the box-like structure at the top of the turbine, and this enables a generator inside the nacelle to convert the kinetic energy of the wind into electrical energy. The electrical energy is then passed through a transformer, increasing the voltage and enabling it to be transported on the National Grid or used nearby. All wind turbines use the same mechanics to generate renewable electricity. A micro turbine located onsite and installed for local generation will have the same operation mechanics as a large scale turbine farm located onshore or offshore.

After the desktop feasibility stage, monitoring the onsite wind potential is essential. This includes determining important factors such as the exact annual average wind speed and the turbulence intensity. This ensures the optimum turbine can be installed to ensure long term, reliable and successful operation.

The average wind speed at the site of installation is naturally a very important factor in the viability of a wind turbine. Sites where the average wind speed exceeds 6m/s (13.4mph) are likely to be most suitable. Turbines are classified according to the average wind speed they are designed to operate in. A wind speed classification of 3 for instance is designed to run at lower speeds. They have large rotors to capture as much energy as possible from lower wind speeds. A turbine with a wind speed classification of 1 is designed for higher wind speeds and typically will have shorter blades to handle the increased loads, they are usually more expensive.

Wind turbines can be controversial in some locations and engagement with the planning authorities and local communities at an early stage is recommended. Obtaining planning for wind turbine developments can be complex and OnGen’s team are well placed to help with this process.

Other factors that need to be considered in determining the suitability of a site for wind generation include the proximity to sensitive areas such as residential settlements, airports and environmentally sensitive locations. Detailed surveys are often required by the planning authorities to understand the impact on landscape designations, ornithology and the potential impact of noise. Visual impact can also be a common area of contention. Many of the impacts associated with wind turbines can be mitigated through careful design in co-ordination with stakeholder engagement and survey research to support the impact assessment report.