European wind – a balanced energy system requires pan-European planning

A concentration of wind farms in the North Sea region is leading to increasing fluctuations in electricity generation.
Published: Wed 26 Jul 2017

With renewables targets to meet it is understandable that countries in Europe have pursued their own goals largely in isolation from other countries. But a consequence of that strategy has been a failure to consider the large-scale wind conditions across the whole continent and as a result, an increase in weather dependent fluctuations in the region’s electricity generation.

This is according to a new study from researchers at ETH Zurich and Imperial College London in the journal Nature Climate Change, who point to the concentration of wind farms in the North Sea region where the weather conditions tend to be similar.

“There is hardly a weather situation in which there is no wind across the entire continent and thus all of Europe would lack wind power potential,” comments Christian Grams, lead author of the study from the Institute for Atmospheric and Climate Science at ETH Zurich.

However, the distribution of the current wind farms is such that the electricity generation is uneven.

“This means that if a stable high-pressure system causes a lull for a few days or even weeks over the North Sea, as happened in the winter of 2016/17, Europe-wide wind electricity generation drops dramatically.”

Weather regimes in Europe

The researchers based their study on combining Europe-wide data on large-scale weather conditions from the past 30 years with wind and solar electricity production data. 

This data was then used to model how wind power is related to seven prevailing ‘weather regimes’ in Europe and how it will change with the further expansion of wind energy capacity.

These weather regimes explain why European wind electricity generation suffers from fluctuations lasting several days with mean generation during different regimes currently ranging from 22GW to 44GW.

Some regimes are characterised by cyclones rolling in from the Atlantic bringing high winds to western Europe, but are accompanied by concurrent calm conditions in the east. Other regimes see calmer weather from the Atlantic but at the same time, wind speeds consistently increase in southern Europe and northern Scandinavia.

The researchers suggest that further concentration of wind power in the North Sea region could lead to even more extreme fluctuations amounting to as much as 100GW between high production in favourable wind conditions and low production during a lull.

However, if European countries were to cooperate and set up future wind farms based on understanding of the continent-scale weather regimes, the fluctuations in future wind energy could be stabilised at the current level of around 20GW. Potential sites include the Balkans, Greece, the western Mediterranean and northern Scandinavia.

These locations would all have enough wind if, for example, high pressure led to a lull in the North Sea. Likewise, if a stable high-pressure area slowed wind production in the Mediterranean, the wind farms around the North Sea would produce enough electricity.

“This is why wind capacity in countries such as Greece or Bulgaria could act as a valuable counterbalance to Europe's current wind farms,” adds co-author Iain Staffell from Imperial College London. “However, this would require a paradigm shift in the planning strategies of countries with wind power potential.”

According to the researchers the energy storage capacity required to balance the large multi-day fluctuations will not be available in the foreseeable future, while using solar energy to compensate for gaps over several days would only work on a regional level at best. In order to compensate for fluctuations across Europe, solar energy capacity would have to be increased tenfold.

Wind in Europe

In an interview with Engerati, Giles Dickson, CEO of the industry association WindEurope, said that wind is now on average over 10% of Europe’s electricity consumption – and consistently 25% or more in Denmark, Ireland and Portugal.

According to Dickson, wind needs investments from both the TSOs and DSOs in interconnectors, particularly the intra-national lines such as north-south in Germany to transmit the wind from the farms in the north to the demand centres in the south, and in the smart grid.

For its part, the wind industry needs to provide more flexibility but less variability in its output, Dickson says.  

Steps in this direction include the use of new generation turbines that are more efficient at low wind speeds and the provision of faster ramp-up and ramp-down times and balancing and ancillary services.

“Data and digitalisation is crucial to solving challenges in the wind industry,” says Dickson.

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