Wind Energy Intermittency

Generation of wind electricity is very intermittent due to weather fluctuations. It is obvious to everyone that wind speed is very variable, but what is less obvious is the fact that these variations are coherent over whole countries such that the total country-wide wind power output can fall to very low values.

Wind turbines have cut-in speed around 12 km/h and below this wind speed, wind turbine electricity output is zero. Examples of wind speed distributions in NW Europe Wind capacity map for NW Europe. Example of coherent low electricity generation all over NW Europe in Feb 2019.

A large fraction of wind energy production in Europe is located offshore in the North Sea or onshore in the low lying regions around it. Wind speed is very correlated on both coasts of the North Sea and so wind production is correlated in adjacent countries.

The amplitude of wind fluctuations is typically between 5 and 60% of installed capacity.

The lows in wind power generation are generally compensated by increased fossil fuel generation. Some countries use imports and exports to compensation for wind lows and highs.

Weather Patterns are large scale and cover large regions of Europe yielding wind speeds and wind power production is coherent over extensive areas. Plots are given to illustrate this with actual wind generation data.