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How effective are high-rise wind turbines?

2 January 2014 Last updated at 10:11 GMT

Several recent skyscrapers have had large-scale wind turbines designed into their structure.

The move is in part down to planning rules which can require major buildings to generate some of their own energy.

With another high-profile tower incorporating a wind turbine nearing completion in London, critics are asking if commercial-scale turbines are effective.

John Moylan reports.