In an earlier post, I outlined some fears I had about wind power, and other forms of renewable energy based on extracting energy from the planets circulatory systems.
This map shows you a historical snapshot of the delicate tracery of wind flowing over the US, on 11th March 2012. Click on the image to see an animated historical or realtime wind map.
The interactive map to the left, shows beautifully the intricacies of real wind patterns. I’d encourage you to explore this real-time animation, where you can zoom into the detail of actual wind movements, or take a look at the entire land mass.
In a recent issue of New Scientist, there is a nice review of the issues we need to think about when considering renewable energy – refreshing to see a more holistic approach to energy consumption.
With regard to wind energy, the article highlights a number of findings I missed in my earlier post:
Wind Speeds are Changing
It seems that we may already be having significant effect on the wind. Wind speeds over the oceans are increasing, while surface winds over Europe, Asia and North America have slowed by up to 15 per cent on average since 1979. That’s pretty significant.
Between 25-60% of the slowdown is thought to be due to changes in land use, with more vegetation and possibly more buildings making the terrain rougher (Nature Geoscience, vol 3, p 756).
What is stunning here is the degree of this change – globally – in just a few years. The wind is not immune to the effects of what we build and what we grow. While this research is not linked to the small amount of energy extracted by wind farms, this could change, and this change would be in addition to the man-made factors described above.
How much power do we need – how much can we get?
At the end of 2011, worldwide wind power generation capacity was just 0.2 TW, but it is growing exponentially. So while the energy we extract now, may not be significant compared to the total energy in the system (see below), it is growing fast and will need to in order to meet our global energy demands (see below).
Wind power: worldwide installed capacity (not actual power generation). GWEC, Global Wind Report Annual Market Update
At the moment mankind uses a little over 16TW of power for all our energy needs. World wide energy demand has been growing exponentially and predictably for the last 350 years. As an example take the figures for US total energy plotted on the logarithmic scale below (the straight line clearly shows a consistent exponential growth of total energy demand):
Total U.S. Energy consumption in all forms since 1650. The vertical scale is logarithmic, so that an exponential curve resulting from a constant growth rate appears as a straight line. The red line corresponds to an annual growth rate of 2.9%. Data source: EIA.
This exponential growth is unlikely to change, until population growth stabilises. More detailed analysis of global energy trends since the 1980′s confirm this trend (see the interactive graph over here at CNN), or the graph below from the Economist.
Put these trends and facts together and you can see that not only do we presently have the ability to have dramatic effect on wind, speed and humidity distribution, but that in the near future our energy demands and technology will allow us to be able to extract a significant proportion of the available energy from a finite and delicate resource – with unpredictable results.
What do the models say?
There is considerable scientific controversy over how much energy would need to be withdrawn from the global system by Wind Power before it would have systemic effects. Based on actual measurements of wind speeds, there is 1700 TW of wind power at an altitude of 100 metres over land and sea. It has been estimated that between 72 and 170 TW of this total figure, could be extracted in a practical and cost-competitive manner.
- A 2004 study by David Keith of the University of Calgary in Alberta, Canada, suggested that the climatic effects of wind power might start to become apparent at a level of 2 TW.
- On the other hand Modelling by Jacobson’s team suggests that extracting 11.5 TW of this wind power would reduce the kinetic energy of wind at 100 metres by less than 1 per cent. The effects on temperature and precipitation are so small they cannot be distinguished from natural variability, he says.
Axel Kleidon and Lee Miller of the Max Planck Institute for Biogeochemistry in Jena, Germany, have argued (controversially), that extracting all the available wind power would produce big changes in temperature and precipitation. While they are not suggesting the world will warm overall, according to their model the local changes are comparable in magnitude to those associated with a doubling of CO2.
It gets even worse higher up
Wind speeds increase the higher you go. In the four jet streams that circle Earth more than 10 kilometres up, wind speeds of well over 100 kilometres per hour are typical.
Exploiting this energy will not be easy, not least because of the way the jet streams meander and change location, but several groups are developing ways to do it. Most involve tethered turbines or kites that turn generators on the ground.
According to some models, extracting really large quantities of energy from these jet streams (1000 TW or 50 times current demand), would have powerful effects, with mean surface temperatures falling by nearly 10 °C, and total rainfall decreased by about 35 per cent and sea ice cover doubled (Energies, vol 2, p 307).
Conclusion
What’s the moral of this story – for a story it is (the scientific facts are inconclusive)? Firstly, allow ourselves to be shocked by how little we know, and how little we spend in researching these things. The above research is a tiny fragment of overall research in this area (it is not fashionable on either side of the debate). It represents tiny groups of individuals with scant resources, trying to predict, model and quantify the impacts of policies that have been allowed to gain acceptance by large sections of the society, and impact national energy policies. Give these guys more money.
Secondly, it is to stop thinking in linear ways whether these be logical or emotional. Look at the systemic effects, and feedback loops. An intervention is not necessarily any better or worse for the environment if it is “natural” or “organic” – it is our linear thinking that is the danger, and our aesthetic judgments have not evolved to lead us to manage finite resources well.
This map shows you a historical snapshot of the delicate tracery of wind flowing over the US, on 11th March 2012. Click on the image to see an animated historical or realtime wind map.
Bruno Latour says that science is an instrument that gives the environment a political voice. We need to listen to the environment, to respect its voice. The wind, like any natural resource it is delicate, yet can have fantastically powerful effects. I have no idea whether wind farms present any real danger to global circulatory systems, but I do know that we have not looked at it carefully enough, and that a true environmental conscience would force us to ask more serious questions before jumping to solutions that please our sensibilities.
We need to listen to the wind.
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