DCTI - Windenergy V.2

85© DCTI 2009 | Volume 2 - Wind Energy CHAPTERV Repowering: Repowering refers to the replacement of outdated turbines with newer and more efficient ones. This process is most common amongst onshore turbines, as they were installed during the 1980s. Peak Load: Peak load is a term used to describe the amount of power needed to supply consumers at a time when demand is the greatest. When energy demand reaches a spike, peak load stations are ope- rated, in order to produce sufficient amounts of electricity at rapid speed. Examples of peak load stations are pumped storage hydro power plants and gas turbine power stations. Electricity Production Costs: The total costs that an energy producer must spend in order to generate electricity. Overspeed Control: Each wind turbine has some sort of overspeed control, which causes the turbine to automatically shut itself down in a situation with high wind speeds, protecting the turbine from damage. Upstream/Downstream: The terms upstream and downstream suggest the direction of the flow of goods. In this context, upstream activities refer to those activities in the value chain which are most distant from the end customer, such as the manufacturing of raw materials, for example. On the contrary, downstream activities refer to those activities in the value chain which are closer to the end consumer, such as the supply of service, for example.