Turbines and turbulence

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Some legitimate questions have been raised over the green credentials of wind turbines. Politics must not block research where it is needed.

Will wind turbines wreck the environment? Last month, the South China Morning Post published a news story that contained a thinly veiled attack on China's wind industry. The article cited herdsmen in a village in Inner Mongolia who say rain stopped falling after the establishment of a nearby wind farm, and meteorologists who backed up the observation with a few years' data that show low precipitation. The article also quoted an engineer in the government's renewable-energy department who hastily dismissed concern over the effect of wind farms, refused to acknowledge the need for research, and asserted the overarching necessity for China to develop wind energy. The article concludes that “wind power is not completely green”. There have been similar attacks on wind energy in Texas and elsewhere.

It is good to see that the newspaper, Hong Kong's most prominent English-language daily, retains a critical stance towards the Chinese government under the 'one country, two systems' policy, and is willing to put Chinese officials on the spot. But in this case, the dismissive official quoted probably has a point. There is no solid scientific evidence that wind turbines can trigger major changes in rainfall. And given Nature's conversations with atmospheric modellers outside China, people are not likely to find any. One expert said the idea that a wind farm could have such a dramatic and demonstrable effect was “silly”.

“Data showed a significant effect of wind farms on near-surface temperatures.”

Wind farms, however, may affect regional or global environmental systems — although to suggest this can draw rapid scorn from wind-power proponents. In 2004, the environmental engineer and atmospheric modeller Somnath Baidya Roy, then at Princeton University in New Jersey, published work showing turbulence created by turbines would, among other effects, lead to vertical mixing of energy and heat in atmospheric layers that would affect local temperatures, and possibly change evaporation patterns (S. B. Roy et al. J. Geophys. Res. 109, D19101; 2004). Some took his study as an attack on the wind industry, and he was besieged with nasty e-mails. They questioned his sanity, threatened to get him fired from his post at Princeton, and accused him of being a pawn of the coal or oil industries. (He has never had nor sought any industrial ties.) The president of one US-based wind-farm firm told Roy to consider “how much heat is your head turning out, while you consider such thoughts?” and to ponder many other factors “while checking your navel for lint”. (We know this because Roy considered the comments humorous enough to post on his webpage.)

At around the same time, other scientists used models to suggest that wind turbines could have effects on climate change and suggested that estimates of these effects should be balanced against their green benefits. Although these researchers are seen by some in the industry as overly critical, they concluded with no stronger recommendation than a call for more research.

In October, Roy, now at the University of Illinois at Urbana-Champaign, published data to back up his theoretical work (S. B. Roy and J. J. Traiteur Proc. Natl Acad. Sci. USA 107, 17899–17904; 2010). A 25-year data set showed a significant effect of wind farms on near-surface temperatures. Roy suggested in the paper that those constructing wind farms should consider low-turbulence turbines or use the results to help find the most suitable sites. It hardly constituted an attack on wind energy. In fact, he says, the main impact — a raising of surface temperatures at night and lowering during the day — could benefit agriculture by decreasing frost damage and extending the growing season. Many farmers already do this with air circulators.

Roy's study was on wind farms with some 20 turbines. Local effects will be more marked in much larger farms. Roy hopes to start a field campaign that can monitor energy fluxes, evaporation, humidity and temperature on a variety of farms as they scale up.

China, developing huge wind farms and planning more, should take a prominent role in such studies. As its facilities expand, it can make solid scientific assessments, which could contribute to a more rational and beneficial use of wind. Although the Chinese official may have been right to dismiss the suggested effect on rainfall, his government should not ignore the need for wider research on the impact of its wind revolution.


  1. Report this comment #17034

    Otto Albrecht said:

    Is this a surprise?
    Who thought that it is possible to remove power without side-effect when the same power, obviously, changes the environment in the places where it is consumed? The commonly known (and acknowleged) effect are elevated temperatures in cities. The power density at the production site might be less, but the total power removed is more, because of losses during transmission.
    Is there anybody who does not recognize that the green hydro-power is not very good for the valleys that might be flooded, the rivers that run dry, the fish that can not migrate?
    The problem is what is less damaging – a steam driven power plant (nuclear, coal or gas) releases two times more power (roughly) at the production site than what arrives at the consumption site – this looks more damaging.
    Our power consumption reaches, locally more than 1% of the naturally released energy (if my old crude calculations and my memory are right). This looks significant, wherever the power comes from...

  2. Report this comment #17037

    Anurag Chaurasia said:

    Wind turbines may have some side effects but eventhough they are better ecofriendly compared to other conventional energy sources.Comperative in depth research is a need of hour.
    Anurag chaurasia,ICAR,India,anurag_vns1@yahoo.co.in,+919452196686(M)

  3. Report this comment #17053

    Margaret Dochoda said:

    Interesting. See image at http://www.windaction.org/pictures/25251 showing clouds forming in the wake of wind turbines of the Horns Rev wind farm off the coast of Denmark.

    The Great Lakes see less ice in recent years, and more lake-effect snow is predicted as a result. One wonders what effect hundreds of offshore turbines will have on local climate in Great Lakes region.

  4. Report this comment #17100

    Long Yanqiu said:

    It is similar to Global Waming. As for earth science or atmospheric science, datas always seem to be inadequate. 25 years is too short compared with the earth's age. How could you ensure it's the turbines that lead to the change in temprature? Further studies should be taken to exclude the natural thrend of climate change. And it may be impossible for our generation, since time is needed to get enough evidence.

  5. Report this comment #18077

    A Jagadeesh said:

    Some of the apprehensions raised in the article on Wind Energy are unfounded.
    The growing fear of global warming and greenhouse gas emissions has led many to seek out alternative forms of energy. One of the most commonly proposed alternate fuel sources is wind power. Wind power is harnessed through the use of wind turbines. Wind turbines provide many benefits that other fuel sources do not.

    Wind is free and it can be captured easily.

    Once the wind turbine is built the energy it makes does not cause green house gases or other pollutants.

    Although wind turbines can be very tall each takes up only a small spot of land. This means that the land below can still be used. This is especially the case in rural areas as farming can still continue.

    Remote areas that are not connected to the electricity power grid can use wind turbines to produce their own supply.

    . Wind turbines are available in a range of sizes which means a vast range of people and businesses can use them. Single house holds to small towns and villages can make good use of range of wind turbines available today

    Wind energy is one of the lowest-priced renewable energy sources.

    A wind farm is a group of wind turbines in the same location used for production of electric power. A large wind farm may consist of several hundred individual wind turbines, and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other purposes. A wind farm may also be located offshore.
    Many of the largest operational onshore wind farms are located in the USA. As of November 2010, the Roscoe Wind Farm is the largest onshore wind farm in the world at 781.5 MW, followed by the Horse Hollow Wind Energy Center (735.5 MW). As of November 2010, the Thanet Offshore Wind Project in United Kingdom is the largest offshore wind farm in the world at 300 MW, followed by Horns Rev II (209 MW) in Denmark.
    The Total capacity of Wind Installations Worldwide upto June 2010,MW:
    USA 36,300 China 33,800 Germany 26,400 Spain 19,500 India 12,100 Italy 5,300 France 5,000 United Kingdom 4,600 Portugal 3,800 and Denmark 3,700 Rest of the World 24,500 and Total 175,000 MW.

    Latest offshore wind statistics released by the European Wind Energy Association (EWEA) confirm that the UK is the European and world leader in the sector, with 1,341MW installed. The UK is followed by Denmark (854MW), the Netherlands (249MW), Belgium (195MW) and Sweden (164MW). Germany, Ireland, Finland and Norway have a further 145MW between them.

    Wind Energy has great future

    Countries like USA,China,South Korea,Taiwan etc., are going in a big way to install offshore wind farms.

    Argentina has windy regions with annual wind velocities around 11 meters per second and estimated wind energy in the country is around 500,000 MW.

    Dr.A.Jagadeesh Nellore(AP),India

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