Off-gridders love wind-power because it’s free, infinitely renewable and doesn’t damage the environment.
Er, wrong on all counts, says a new report by German scientists which challenges virtually all our assumptions about wind-power as a sustainable energy source, and questions wave-power for good measure.
According to the study carried out by the respected Max Planck Institute for Bio-geochemistry in Jena, Germany, wind and wave energies are not infinitely renewable after all. They can be ‘used up’ if there are too many turbines built.
Worse, says the study, the climate effects of using too much wind and wave energy could be comparable to doubling atmospheric concentrations of carbon dioxide. So the environmental costs could be enormous.
The conclusions may sound nonsensical but they are based on the concept of ‘free’ or usable energy, says academic Axel Kleidon who led the research. “Although the earth receives an enormous amount of energy from the sun, 99 per cent of it is reflected back into space. Only the remaining one per cent is usable by wind and wave power.”
He says the earth receives 100,000 terawatts of energy from the sun. Of this 99% is reflected back into space, leaving just 1,000 tw of ‘free’ energy. Of this, three quarters is unusable because it is over oceans, leaving 250 tw. At best you can be 50% efficient in energy conversion so this leaves maybe 120tw of ‘free’ energy.
He says that currently human beings use nearly 50tw of energy, nearly 20tw of it in fossil fuels and close on 30 in food production. This total is predicted to rise to 80tw by the end of the century –a level that is beginning to approach the limits of what is available.
The impact wont be immediate says Kleidon and still leaves room for wind as a transitional source of power. But in the long run it is unsustainable he says: “We have to understand that human beings play a substantial role in planetary energy usage and that role is getting bigger.”
” We need to understand that the human race is a real factor in the use of planetary energy. Human beings certainly use more of the free energy than all geological processes put together. More than all the earthquakes, volcanoes and tectonic plate movements put together.”
Although the winds will not die altogether, taking that much energy out of the atmosphere in the long run could result in substantial climate change. “The first signs will be an impact on local wind patterns affecting the efficiency of wind farms. The result of reduced energy in the atmosphere could also be changes in precipitation, turbulence and the amount of solar radiation reaching the Earth’s surface.”
Kleidon’s findings may sound outlandish and even alarmist, but they are being taken seriously by the scientific community. “While I might quibble with the details, there is a crucial message here for mankind. He is saying that there is a finite amount of free energy. It shows that there is no such thing as a free lunch. You don’t get something for nothing in the physical world. Kleidon’s calculations have implications for attempts to transform our energy supply,” says Peter Cox, Professor of Climate Studies at Exeter University
His view is supported by meteorologist Maarten Ambaum of the University of Reading, UK. “This is an intriguing point of view and potentially very important. Human consumption of energy is substantial when compared to free energy production in the Earth system. If we don’t think in terms of free energy, we may be a bit misled by the potential for using natural energy resources,” he told the UK’s New Scientist magazine
The implication of the study is that in the long run only solar power will be able to fulfil mankind’s energy needs without serious climatic damage, says Kleidon. He said that the Max Planck Institute is funded exclusively by the German government. “We receive no help from solar, nuclear, oil or conventional electricity companies. This study has no commercial agenda.”
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