Cham-Longe wind farm energy assessment

Wind farm repowering energy assessment leading to low uncertainty level

Boralex – France’s largest independent producer of onshore wind power

The Cham-Longe wind farm in the south of France has been built in December 2005 and will reach 15 years of operation in 2020, meaning the end of the advantageous feed-in tariff for a direct sale at the price of the EPEX SPOT market. Boralex intends to build a new wind farm with more powerful turbines leading to higher energy production and higher revenue for each megawatt hour produced thanks to the possibility to apply to the new French Contract-for-difference, more favorable than a sale on the EPEX SPOT market. Boralex sought a partner to provide an independent energy assessment for the future 35 MW wind farm which will replace the existing one. The low quality of the measurement mast data and the complexity of the terrain was a real challenge at this site.

DNV realised an energy production assessment based on different sources of data.

Step 1
On the one hand, meteorological mast and mesoscale data, were used to define the wind regime at the Cham-Longe site.

Step 2
On the other hand, operational SCADA data, together with long-term reference sources, were used to define the long-term energy production at the existing Cham-Longe Wind Farm.

Step 3
The wind regime derived in Step 1 was adjusted so that the energy production estimate resulting from this wind regime matches the energy production at the existing Cham-Longe Wind Farm derived in Step 2.

Step 4
The adjusted wind regime from Step 3 was used to estimate the energy production of the future repowered Cham-Longe Wind Farm.

Value to customer
The methodology employed allowed a validation of the wind regime and of the wind flow model. Therefore, the overall 10-years energy uncertainty is low, 8.1%, and below what would typically be achieved – 10% to 11% – for an equivalent analysis but based exclusively on high mast data quality.

This low uncertainty level led to good financing conditions and Boralex was one of the few winners from the second French onshore wind tender.

Following the success of this first repowering energy assessment for the DNV team in France, a second repowering energy assessment is planned for the last quarter of 2018.