Steady flow equation

Bill Hyde criticises the statement that ‘even at low wind speeds turbines are producing electricity’

Bill Hyde in his letter in the October issue of PE criticises the statement I quote that ‘even at low wind speeds turbines are producing electricity’. 

I think that independently of my source one could deduce that from application of the First Law for an open system (the ‘steady flow equation’) to a wind turbine. Is it therefore fair of Bill Hyde to impute with ‘ignorance’ the authority which I quote? He seems to be pointing a warning finger at me in his penultimate paragraph. Assertion of his own knowledge and experience in the final paragraph is not convincing justification for this.

Dr John Jones, School of Engineering, University of Aberdeen

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