The power output of wind farms can be increased at least ten-fold simply by optimizing the placement of turbines on a given plot of land, U.S. researchers say.

Researchers at the California Institute of Technology have been conducting a field study at an experimental 2-acre wind farm in northern Los Angeles County.

Despite improvements in the design of wind turbines, wind farms are rather inefficient, researcher John Dabiri said.

Modern farms generally employ horizontal-axis wind turbines, the standard propeller-like giants that have to be spaced far apart, and not just far enough that their giant blades don't touch.

With this type of design, the wake generated by one turbine can interfere aerodynamically with neighboring turbines, with the result that "much of the wind energy that enters a wind farm is never tapped," Dabiri said.

At their experimental facility, Caltech researchers are using vertical-axis wind turbines that have vertical rotors and look like eggbeaters sticking out of the ground.

Such wind turbines are ideal, Dabiri said, because they can be positioned very close to one another.

Tests showed that an arrangement in which all of the turbines in an array were spaced four turbine diameters apart -- about 16 feet -- completely eliminated the aerodynamic interference between neighboring turbines.

By comparison, propeller-style wind turbines would require spacing them about 20 diameters apart, a distance of more than a mile between the largest wind turbines now in use.

The vertical turbines at the Caltech experimental farm generate 21 to 47 watts of power per square meter of land area, whereas a comparably sized horizontal turbine farm generates just 2 to 3 watts per square meter, the researchers said.

earlier related report
Poland should drop nuclear
Warsaw (AFP) July 13, 2011 - Poland should turn to offshore wind farms for safer, cheaper energy and more jobs instead of pushing ahead with plans to build its first nuclear power facility by 2020, a study said on Wednesday.

"Either we'll choose the dangerous atom and pay higher energy bills or we'll invest in offshore wind farms on the Baltic, thanks to which we'll pay less for electricity and create more jobs," Maciej Muscat, head of Greenpeace Poland said in a statement as the findings of a fresh study, "Sea Wind vs. the Atom" were made public.

It concluded that rather than pushing ahead with plans to build a three gigawatt nuclear facility, 2004 ex-communist EU member Poland should invest in 5.7 gigawatts-worth of offshore wind farms off its Baltic Sea coast.

A move to wind energy would generate more than 9,000 jobs, compared to 7,000 in the nuclear sector and competitively-priced electrical power at 104 euros (146 dollars) per megawatt hour in stead of 110 euros per megawatt hour for nuclear power, the study said.

Authored by Grzegorz Wisniewski, head of Poland's Institute for Renewable Energy (IEO) and commissioned by Greenpeace Poland and Germany's Heinrich Boell NGO, the study also alleged that the Tusk government had significantly understated the costs of nuclear energy -- at about 67 euros per megawatt hour.

Using models developed at the Massachusetts Institute of Technology (MIT) "analysis in our report shows the government's Program for Polish Nuclear Energy has understated the price of nuclear energy by half" of its actual cost, Muskat said.

"It's unacceptable that they're trying to foist the atom on Poles based on false data," he added.

Poland's Prime Minister Donald Tusk has said that Germany's decision to phase out nuclear power by 2022 will not change Warsaw's mind about forging ahead with nuclear power.

Warsaw plans to invest about 25 billion euros (35 billion dollars) in nuclear power.

With a population of 38 million, 2004-EU entrant Poland currently has no nuclear power facilities and relies on greenhouse gas producing coal for 94 percent of its electricity.

This poses a challenge to Warsaw's commitment under the EU climate package to reduce greenhouse gas emission by 20 percent by 2020.

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