26.07.2011
Campaign against wind in USStudy finds benefits of wind negligible
A study conducted by Bentek Energy of Colorado finds that the claims that wind power offsets carbon emissions are "significantly overstated and... so small as to be insignificant or too expensive to be practical."
So why does the study confirm AWEA's figures for CO2 offsets?In a study released this week by Bentek Energy, a claim reportedy made by the American Wind Energy Association (AWEA) comes under attack in particular, and the study's findings are making headlines in the business world, such as at Forbes. The study is not readily available online, but the firm made a copy available to Renewables International and put us in contact with the author. Those wishing to purchase a copy can contact info@bentekenergy.com; the company was not able to state a price.
The summary at Forbes hones in on an alleged AWEA estimate that, as Forbes puts it, "every megawatt-hour of electricity produced by wind turbines cut carbon dioxide emissions by 0.8 tons" – an unusual formulation, since most organizations would talk about how many tons of carbon are offset on the average. Indeed, a search online for statements made by AWEA for the number of times that "every megawatt-hour" of wind power leads us back to this study, not to any claims by AWEA.
Instead, we find more balanced assessments, such as this one...
http://www.renewablesinternational.net/campaign-against-wind-in-us/150/505/31471/***********************************************************************************************
From the journal published by the International Electric and Electrical Engineers on the topic of the OP. This is written by a group of the worlds leading experts on wind energy grid integration.
It completely rebuts the impression that those disseminating the study in the OP are trying to create.
Wind Power Myths Debunked november/december 2009 EEE Power and Energy Magazine Master Serie
You can download for free this (normally $26 article) here:
http://www.ieee-pes.org/images/pdf/open-access-milligan.pdf
Doesn’t Wind Power Need Backup Generation? Isn’t More Fossil Fuel Burned with Wind Than Without, Due to Backup Requirements?
In a power system, it is necessary to maintain a continuous balance between production and consumption. System oper- ators deploy controllable generation to follow the change in total demand, not the variation from a single generator or customer load. When wind is added to the system, the vari- ability in the net load becomes the operating target for the system operator. It is not necessary and, indeed, it would be quite costly for grid operators to follow the variation in generation from a single generating plant or customer load. “Backup” generating plants dedicated to wind plants—or to any other generation plant or load for that matter—are not required, and would actually be a poor and unnecessarily costly use of power-generation resources.
Regarding whether the addition of wind generation results in more combustion of fossil fuels, a wind-generated kilowatthour displaces a kilowatthour that would have been generated by another source—usually one that burns a fos- sil fuel. The wind-generated kilowatthour therefore avoids the fuel consumption and emissions associated with that fossil-fuel kilowatthour. The incremental reserves (spinning or nonspinning) required by wind’s variability and uncer- tainty, however, themselves consume fuel and release emis- sions, so the net savings are somewhat reduced. But what quantity of reserves is required? Numerous studies conducted to date—many of which have been summarized in previ- ous wind-specific special issues of IEEE Power & Energy Magazine—have found that the reserves required by wind are only a small fraction of the aggregate wind generation and vary with the level of wind output. Generally, some of these reserves are spinning and some are nonspinning. The regulating and load-following plants could be forced to oper- ate at a reduced level of efficiency, resulting in increased fuel consumption and increased emissions per unit of output.
A conservative example serves to illustrate the fuel- consumption and emissions impacts stemming from wind’s regulation requirements. Compare three situations: 1) a block of energy is provided by fossil-fueled plants; 2) the same block of energy is provided by wind plants that require no incremental reserves; and 3) the same block of energy is provided by wind plants that do have incremental reserve requirements. It is assumed that the average fleet fossil-fuel efficiency is unchanged between situations one and two. This might not be precisely correct, but a sophisticated operational simulation is required to address this issue quantitatively. In fact, this has been done in several studies, which bear out the general conclusions reached in this simple example.
In situation one, an amount of fuel is burned to produce the block of energy. In situation two, all of that fuel is saved and all of the associated emissions are avoided. In situation three, it is assumed that 3% of the fossil generation is needed to provide reserves, all of these reserves are spinning, and that this generation incurs a 25% efficiency penalty. The corresponding fuel consumption necessary to provide the needed reserves is then 4% of the fuel required to generate the entire block of energy. Hence, the actual fuel and emis- sions savings percentage in situation three relative to situ- ation one is 96% rather than 100%. The great majority of initially estimated fuel savings does in fact occur, however, and the notion that wind’s variations would actually increase system fuel consumption does not withstand scrutiny.
Let's look at the final two paragraphs more closely
Compare three situations:
1) a block of energy is provided by fossil-fueled plants;
2) the same block of energy is provided by wind plants that require no incremental reserves; and
3) the same block of energy is provided by wind plants that do have incremental reserve requirements.
It is assumed that the average fleet fossil-fuel efficiency is unchanged between situations one and two.
This might not be precisely correct, but a sophisticated operational simulation is required to address this issue quantitatively. In fact, this has been done in several studies, which bear out the general conclusions reached in this simple example.
In situation one, an amount of fuel is burned to produce the block of energy.
In situation two, all of that fuel is saved and all of the associated emissions are avoided.
In situation three, it is assumed that 3% of the fossil generation is needed to provide reserves, all of these reserves are spinning, and that this generation incurs a 25% efficiency penalty.
The corresponding fuel consumption necessary to provide the needed reserves is then 4% of the fuel required to generate the entire block of energy. Hence, the actual fuel and emissions savings percentage in situation three relative to situation one is 96% rather than 100%. The great majority of initially estimated fuel savings does in fact occur, however, and the notion that wind’s variations would actually increase system fuel consumption does not withstand scrutiny.
Now please review the first article in this post that reviews the Bentek study specifically. It should make more sense.