WindMax: Monthly digest of wind turbine operating data -- October 2016

GERMANY/DENMARK: Windpower Intelligence, the data and research division of Windpower Monthly, has teamed up with the Imperial College Business School of London to analyse and publish the output and capacity factors of operating wind turbines in Germany and Denmark.

Offshore keeps up the numbers

The gap between the output of wind turbines in Denmark and Germany was particularly pronounced during October.

Data collated over the month from more than 11,000 wind turbines with a combined installed capacity of over 16GW revealed that while Denmark’s turbines achieved an impressive average capacity factor of 34%, those in Germany were ticking over at just 13%.

While the German figure was marginally better than the average for August (12%) and September (11%) it now marks eight consecutive months where output has fallen below the 20% level.

By contrast, Denmark’s average of 34% during October was well above August’s 27% and September’s 19%. This discrepancy can be partly explained by wind speeds.

According to figures published by consultancy AWS Truepower in its Wind Trends Bulletin, wind speeds in and around Denmark were around 5% higher than the October average, while across Germany they were 15% down.

Another factor is the greater proportion of offshore turbines in Danish waters that contribute to this analysis. Even the best-performing onshore models achieved capacity factors of 10-15% — with one or two notable exceptions — but offshore turbines performed much more impressively.

For this month’s analysis we have separated the figures for Siemens’ onshore and offshore turbines to provide a clearer picture of how production output varies.

There are a handful of Siemens’ new 6MW and 7MW offshore models reporting data, but most are older 2.3MW models or the industry’s best-selling 3.6MW workhorses. Combined, they push the company’s offshore capacity factor to a mean of nearly 40% for the month, whereas that for onshore is below 30%.

Vestas turbines generally performed well during October, though this can largely be explained by the number operating in its home market, Denmark, and taking advantage of the higher wind speeds.

Siemens 3.6MW tops the charts

A remarkable capacity factor of 60% was recorded by the Siemens 3.6MW offshore turbine. Other offshore models, including MHI Vestas’ V164-8MW and Senvion’s 5MW and new 6.2MW turbine, averaged around 40%. Low numbers of these models are contributing to this analysis, and some are prototypes installed onshore.

Evidence, though, of what a modern onshore turbine, mounted on a tall tower can achieve, even when wind speeds are disappointingly low, is provided by the single 3.3MW Nordex turbine. This Germany-based turbine achieved an average capacity factor of over 30% during October.

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