Jul 21 2012

Bigger the Better

Published by under Student blog entries

Summary and Response  to National Geographic’s  “Sizing Up Wind Energy”

http://news.nationalgeographic.com/news/energy/2012/07/120720-bigger-wind-turbines-greener-study-says/

Wind technology has developed so much that some turbine diameters can surpass the length of a football field.

As population grows and global energy demand increases, climate change and levels of greenhouse gasses are increasing and fossil fuel resources are declining.  There is a clear strong movement in the direction of renewable energy.  Wind energy is one of the leading technologies. In the 1980’s a wind turbine could generate around 50 kW of energy, and today many have a capacity of 3,000 kW.  Unfortunately though wind energy has slowed its progress—from 1980-2003 energy generation doubled every four years, but in the past ten years it has only increased marginally according to Stiesdal, chief technology officer for wind energy at Siemens (a large international turbine manufacturer).

To increase wind turbine capacity, developers are attempting to increase turbine size.  Because larger turbines are higher off the ground, they reach air that is higher in the wind column moving at greater speeds.  These larger turbines have a higher capacity, and they don’t cost that much more to manufacture.  Fort Felker, director of the wind technology center at the U.S. Department of Energy’s National Renewable Energy Laboratory in Golden, Colorado points out that if we use big, high-efficiency turbines a new wind farm of 500 could be as productive as a current small-turbine farm of 1,000.  Additionally, “the cost has been reduced by a factor of ten or so, from unaffordable levels to where it is right now, able to compete with conventional power sources.”

However, we sometimes fail to address the resources that go into making these turbines.  Most of the power take-off systems for the wind turbines require rare earth magnets that can only be attained through deep (and expensive) mining.  Then we must consider transporting these huge parts and installing them.  Though the changes may seem marginal, each size increase raises the price and energy used.  Also after a certain point, “the weight goes up cubed, but the energy capture only goes up squared.”  These considerations make wind energy seem a little less renewable.

What we need to do is optimize the turbine size and energy capacity and minimize transportation and production costs. Recently though Felker said, “The cost has been reduced by a factor of ten or so, from unaffordable levels to where it is right now, able to compete with conventional power sources.” In the future, the industry aims to make turbines with fewer and lighter parts and ones that have better controls and efficiencies.

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