The author of these pages has no financial connection to either side of the wind power 'debate' and is entirely independent.
Most of the links on this page lead to further explanation and supporting evidence.
The main subject of this page is Dr Sexton's outrageous claim – the basis of his submission to the parliamentary committee – that it would take as long as 3580 years for the Ceres wind farm in South Australia to recover the carbon dioxide emissions released during construction. When one looks into the facts one finds that Dr Sexton's figure on the amount of CO2 released from the concrete of turbine footings is too high by a factor of twenty while his calculation of the amount of CO2 abated by the turbines is too low by a factor of 3000 giving a total error factor of 60,000. To top off his submission Dr Sexton unethically and illegally used one of my photos.
Dr Sexton's submission was given at a public meeting, parts were repeated by member of the SA Legislative Council, David Ridgway, and parts were published in the Yorke Peninsula Country Times.
"The facts presented in our Parliamentary Select Committee Inquiry were obtained from independent research, using highly objective professional parties and data sources and we do not intend to engage in a pointless debate with you".It would have been greatly to be preferred if he had retracted rather than my having to expose him, but as I am not willing to allow any prominent person to publicly libel renewable energy with impunity I have written this page.
I will start with a very small error that Dr Sexton made, but one that indicates carelessness. On page seven of his presentation Dr Sexton says "We understand that the size of the hole to be excavated for each wind turbine would be equivalent to at least a 25 metre Olympic Swimming pool, and require between 2000 and 3000 cubic metres of concrete for each turbine." (An Olympic swimming pool is 50m long; there are no 25m Olympic swimming pools; see Wikipedia).
More importantly, Peter Sgardelis of the Ceres project told me the footings would be "a maximum of 475 cubic metres", and this is if the foundations are what is called 'gravity' type; if there is suitable bedrock to which they can be bolted they can be about half this size.
So Dr Sexton has overestimated the amount of concrete needed for each turbine by a factor of at least four and perhaps as much as twelve. (In figures that an economist might more easily understand, 400% to 1200%.)
On his page eight Dr Sexton seems to be confusing tonnes with cubic metres and cement with concrete. About 900kg of CO2 are released during the manufacture of each tonne of cement (see CO2 and wind turbine concrete). Concrete is roughly 11% cement, the bulk of it is sand and gravel, and its specific gravity is about 2.5 times that of water (ie. 2.5 tonnes/cubic metre). So 2000 cubic metres of concrete weighs about 5000 tonnes and would contain about 550 tonnes of cement (and this would release about 500 tonnes of CO2 during manufacture). In fact, if each footing is 400 cubic metres, it will contain about 1000 tonnes of concrete, 110 tonnes of cement, and this would involve the release of about 100 tonnes of CO2 – not Sexton's 2000 tonnes!
So Dr Sexton has overestimated the amount of CO2 released for each turbine by a factor of 20. (Economist's figure: 2000%.)
On his page ten Dr Sexton claims that 300MW of backup generation capacity will be required for the 600MW Ceres wind farm and seems to imply that this will have to run all the time. Of course backup is needed for all power stations, but no special additional backup has been added for the wind power currently in South Australia, so there is little or no evidence that any more will be needed for the Ceres wind farm.
To calculate the amount of electricity generated in a year by a typical Australian wind farm one multiplies the installed capacity by the capacity factor then by the number of hours in a day and the number of days in a year. So, in this case, 600MW × 0.35 × 24 × 365 = 1,839,600MWh/year; that is, a wind farm of 600MW installed power, like Ceres, can be expected to generate around two million megawatt hours of electricity each year.
So Dr Sexton has underestimated the amount of power generated by the wind farm by a factor of 3000 or more! (Economist's figure: 300,000%.)
In total, because Dr Sexton's error multiply, he has overestimated the time the wind farm will take to pay back the CO2 released during construction by a factor of something around 20 × 3000 = 60,000!
None of what has been discussed above deals with different interpretations of evidence, or differences in choice of calculation methods. Dr Sexton's mistakes seem to be the result of poor research and logic, including not understanding the distinction between cement and concrete; not finding out the volume of concrete required; and not understanding the difference between power and energy.
It seems that Dr Sexton copied the image from a Facebook page that I wrote, Ceres Wind Farm, The Debate.
Anyone who has followed the 'debate' on wind power will not be surprised to learn that Dr Sexton's botched calculations were eagerly copied by anti-wind people such as politician David Ridgway and the anonymous author of Stop These Things.