Chapter 2
Introduction | Discussion of Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | Chapter 6 | Chapter 7 | Chapter 8 | Chapter 9 | Chapter 10 | Chapter 11 | Chapter 12 | Conclusion | Appendix
Chapter 2, ‘Wind energy’, begins with the political and institutional aspects of renewable energy, especially wind power, as considered mostly for the UK economy. Etherington describes the UK governmental targets, but concentrates on electricity supply. Correctly, he identifies the shortfall between the government’s targeted capacity for wind power and the actual present installed capacity. He then backtracks to an historic review of wind energy, which progresses somewhat illogically into his expressing his own severe doubts about the authenticity and independence of the UN International Panel on Climate Change (IPCC). ‘Reducing fossil fuel use and controlling carbon dioxide emission’ is a ‘perceived need’, ‘in part deliberately cultivated’ ‘in response to powerful lobbying by well-intentioned green campaigners and less altruistic pressure from multinational power companies’*. The chapter continues by considering wind shear as a function of height, and, in a somewhat muddled manner, turbulence in the wind. As is common with many accounts of wind, wind-speed statistics are given mostly without clear identification of the heights involved. The vital need to understand the probability distributions of wind speed is completely neglected, with the reader told of the ‘Long persistence of wind-free or low wind conditions [acrossEngland and Scotland]’; no frequency of occurrence and no mention of prediction of such circumstances are included.
Chapter 2 continues with a description of the Lanchester-Betz limit of energy capture and the non-linear relationship of energy capture to wind-speed. The averaging of wind power generation across a windfarm and region is acknowledged, but with an emphasis on the significant changes in a nation’s wind power generation over periods of days. The steadily increased size of state-of-the-art turbines is recognised, but there is no recognition that for a given total capacity the larger size means far fewer turbines in a vicinity. Etherington now considers the National Electricity Grid and the need to balance supply and demand. Although most of the technical basics are correct and well-explained, he fails to mention that demand is constantly changing, and that supply has to be altered to match the demand. This omission is serious, since the impression is given that variations as from wind power are distinct and previously unknown, whereas the variations due to changes in load have always been similar and predominantly more extreme. Thus a grid that copes with load/demand variation, copes easily with the arrival of wind power. A similar unforgivable error is not to mention that all forms of generation fail and hence need back-up strategies. Maintaining short-term operating reserve capacity with a range of mechanisms to balance supply and demand have always been the central tasks for grid operators (see Appendix). Losing connection unexpectedly to a 2 GW nuclear power plant or a submarine cable international connection is a severe test for grid operation; far more severe than the slow loss or gain from aggregated wind power. Moreover, outages of central generation and main transmission can be unpredicted and sudden (of the order of seconds), whereas total wind power is accurately predictable to hours ahead and strategically predictable days and weeks ahead. The failure of a single turbine or a single onshore windfarm connection is not noticed by grid operators. Etherington’s failures to mention such factors are unforgivable errors of omission that are used to bias the case against wind power.
Another significant error is that Etherington states that all generators, including individual wind turbines, have to reach exact synchronism with the 50 Hz grid before a mechanically switched connection is made. This is wrong. The error partly arises because he fails to appreciate induction generators and solid-state electronic interfaces; two essential technologies of wind power. Consequently he fails to mention and explain variable speed turbines, which benefit both visual impact and capture efficiency. A less important error is that he does not appreciate that generators are multipole and so gearboxes are not alone responsible for relating rotor frequency to grid frequency. I do not blame an ecologist for not knowing such details of electrical engineering, but I do blame him for making dogmatic conclusions from such errors, as he regularly does against wind power.