Global Wind Energy Index
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Understanding Your Asset's Performance


It is not unusual for wind farms, to yield significantly below or above what was expected when looking at a shorter time frame, which although can be more years. It is most likely because the available energy from the wind climate, deviated from the predicted long term annual average value.

The primary purpose of the EMD Wind Index service, is to provide wind turbine owner and operators with more or less advanced processed data to evaluate the performance of their wind turbines by correcting actual production for available wind energy at the specific project.

EMD Global Wind Energy Index service, provides as well free of charge simple Wind Energy Index as refined versions with very low uncertainty, historical data, API access etc. at subscription basis.

When dividing the actual production with the wind energy index for a specific period and correcting for period length, you get the expected long-term production. By comparing to the pre-determined and expected long term average you have a quite precise performance measure for your asset. The underlaying data fueling these data is processed ERA5t Global data.


We offer three levels of services: Regional Index, Location Index, and Turbine Index

  • Turbine Index has an uncertainty as low as 3-4% and we typically observe a 99% correlation between the Turbine Wind Index and the actual potential production from wind turbines.
  • Location Index service has around 6-8% uncertainty when comparing wind turbines potential production to the wind index numbers.
  • Regional Index has above 10% uncertainty, but it is offered free of charge.

For more information, read the Technical Note.


All Prices are excluding Danish VAT. which is not charged when

  • a) informing your EU VAT number or
  • b) if your company is domiciled outside the EU.

Turbine Index

EMD's new Turbine index provides a new and unique wind energy index service with low uncertainty. Using the historic performance of the individual turbine's operational data to train our advanced AI we can generate a high quality turbine index. This AI is capable of considering wake effects, summer/winter biases, hill effects and neighboring wind farms.

The Turbine Index is so tightly connected to the expected performance of the individual turbines, that not only can the Turbine index be used to normalise the past months production, with the lowest possible uncertainty, but it also details the individual turbines past operational behavior. This can be used as a reference to detect degradation over time, or sudden drops in performance.

Subscription to the Turbine index, enables you to download hourly windspeed and modelled production for each turbine through an API connection. You will therefore get a simple modelled digital twin imported into your existing monitoring system where you are in control of how to use the data.

Location Index

The Location index, is comparable to a traditional windfarm wind energy index. Here the wind speed is scaled by a distance weighting of the four nearest ERA54t nodes to the chosen coordinates of your windfarm.

Furthermore, the windspeed can be scaled to the expected site specific mean wind speed at hub height, and will use the turbine specific power curve to convert wind speed to power.

This will create a wind index which is more aligned with the production dynamic of your specific project.

Subscription is required for the Location Index Service, which enables you to get notifications every month when a new wind index is ready. It also gives access to an API connection where you can download the wind index data directly to your inhouse monitoring system automatically. The index starts January 2000 and is updated every month into the future.

Regional Index

For a 0.25 x 0.25 degree rectangular grid (approx.. 30 x 30 km resolution), the wind speed at 100 meters above ground level is converted to power using a generic large wind Turbine, with rated power at 12m/s.

This creates an hourly time series of production, from the year 2000 up to today and its updated with a 7 day delay every month. This hourly production is then aggregated to monthly productions, and every single month it's indexed relative to the pre-determined long-term representative period covering 15 full years, starting January 2004 and ending December 2018. This 15-year average in thus the reference Index 100% period, which all individual months are index to as a % in order to obtain the Monthly Wind Energy Index value.

The free Regional Wind Index is using a generic power curve, and no scaling of wind speed. This index will therefore have some uncertainty of its representativeness, compared to a specific turbine type with a different power to wind speed response. This can be mitigated using the Location index.