Landscape Characteristics of Welsh Wind Power Station Sites

Capacity Definitions and Effectiveness of Wind Turbines

Wind power could be a useful contributor to our energy needs, but it is unreliable and inefficient and its benefits are outweighed by the adverse impact of large numbers of turbines upon our countryside.

CPRW readily accepts that wind turbines can generate electricity without producing polluting gases and that, on the face of it, wind power seems to be one of the more promising replacements for fossil fuels. Unfortunately, winds of the optimum speed are periodic and unpredictable - and so is the power generated. This uncertainty has allowed interested parties to exaggerate the electrical output of wind turbines by the misleading use of the following definitions:

• Installed Capacity (IC) - the total output technically possible, assuming continuous power generation. Thus, the IC of 20 turbines rated at 600 kilowatts (kW) is 12 megawatts (MW): (1 MW= 1000kW).

• Capacity Factor (CF) - actual or predicted output as a % of IC. Specific calculations by the government and the wind industry assume a 30% Capacity Factor, still significantly above the average achieved.
  
  
• Declared Net Capacity (DNC)-the government's theoretical expression of "the maximum power available due to the intermittent nature of wind energy". This concept is used in strategic planning and policy documents and employs an artificial Capacity Factor of 43% of IC in order to make comparisons with other energy sources.

Despite this, Welsh wind power station's have operated at below 25% Capacity Factors for the last two years, and the UK average has only been lifted slightly above this lever by the considerably higher performance of the installations in Northern Ireland.