PROS AND CONS OF WIND POWER
NOT SO FREE ENERGY FROM THE AIR
Like most other technologies, there are pros and cons of wind power. But the promise of wind power is compelling. Wind power offers all of the power humanity will ever need, with no air or water pollution, and from resources that will last as long as the sun shines.
But there are some hurdles.
Although wind power is an eloquently simple technology, its application gets complicated, and, like just about everything else, it comes at a price. There are six main aspects of the pros and cons of wind power.
Pros and Cons of Wind Power Environmental Friendliness -
Pros and Cons of Wind Power Reliability -
Pros and Cons of Wind Power Cost -
Pros and Cons of Wind Power Availability -
Pros and Cons of Wind Power Aesthetics -
Pros and Cons of Wind Power Sustainability -
[Note: Most of the opinions expressed in this discussion of the pros and cons of wind power come from the following web resources:
Wind power opponents:
Industrial Wind Energy Opposition
National Wind Watch
Stop Ill Wind
Wind power advocates:
American Wind Energy Association
World Wind Energy
An excellent resource with more information about the pros and cons of wind power can be found at this
Wikipedia, Pros and Cons of Wind Power
Each site contains a number of links to more wind power information.]
PROS AND CONS OF WIND POWER - ENVIRONMENTAL FRIENDLINESS
One of the biggest environmental problems with wind power is the land area required for placement of wind generators. Advocates claim that the actual land used by a wind turbine ends at its base. They also state that some of the best wind resources are just off the coasts and that those generators would occupy no land area.
Anti-wind groups say that the space occupied by wind generators is far larger than just the base of the generator. The actual footprint includes a safety zone around each generator and is at least 5 acres.
Wind generators also need ‘clean’ wind to operate efficiently, so trees within a 30 or so acre area around wind turbines are often cleared. And each generator needs access roads for ongoing maintenance and power transmission lines.
According to many anti-wind groups, when all is said and done, wind generation will occupy land areas of over
50 Acres Per Megawatt
of power output.
If anti-wind groups are correct, then 60,000 acres would be required to produce the same power output as a large, 1.2 gigawatt, conventional power plant which occupies less than 200 acres of land.
That means that wind turbines would use about 300 times the amount of land as conventional power plants. Estimates vary a great deal, and depend partly on who is doing the estimating.
Note: Considering everything including access roads, safety areas that are actually used (many aren’t fenced off), the fact that most conventional power plants include large grassy areas not occupied by structure, and not including power generated by off shore wind generators, a real world number looks more like 15,000 to 20,000 acres of wind generator area to install the same power generated by a conventional power plant occupying about 150 acres of constructed area; or about 100 times the amount of land. And you will find plenty of argument about that number from both sides of the pros and cons of wind power.
The real question regarding landmass required for wind power generation is whether or not we have enough land to place enough wind generators to supply our needs.
As discussed on the
energy pages, the United States contains about 2.26 billion acres.
If we use the high figure of about 60,000 acres to replace one large conventional power plant, and if we estimate that we have about 1,000 power plants to replace, then we see that it could, in theory, require as much as 60 million acres of land to harness enough wind power in the U.S. to replace most of our existing power generation with wind power. That would leave at least 2.2 billion acres for other uses, probably more.
There are a number of factors that affect the actual land area used for wind power and most of these will be discussed below. Some things will increase land area usage, and others, especially the massive offshore wind generation capability we have at our doorstep, will greatly decrease it. The main point is that we do have adequate land resources to harness wind energy.
But anti-wind groups say that land use is only one of a number of environmental problems with wind generation.
Bird kills associated with wind generators have created another area of pros and cons of wind power. Wind power advocates say that birds are also killed by flying into windowpanes and other stationary structures; and birds as well as many other animals are killed by pollution from existing power plants. Advocates also say that they are working on solutions to the bird kill problem.
Anti-wind power groups insist that the ratio of bird kills by wind generators is far greater than those killed by autos or windowpanes. But hard evidence of that is difficult to find.
A larger environmental problem centers on one of the main reasons wind power has been pursued so enthusiastically. Beyond ‘free’ energy, wind power has promised to deliver clean energy. But some believe that reality has not kept up with the dream.
At first glance, wind power seems like a straightforward proposition. Every megawatt generated by wind should reduce fossil fuel power plant demand by a megawatt. More wind generators should mean less fossil fuel burned.
But, because of the realities of providing reliable electrical power to the grid, we do not get anything approaching a one-megawatt reduction in demand for every megawatt of wind power installed.
The reality is only a small fraction of what was previously thought.
We’ll discuss this problem below.
PROS AND CONS OF WIN POWER RELIABILITY
Maintaining reliability of the
is more than a matter of convenience; it is required to maintain civilization as we know it.
Our electrical supply is the miracle of the industrial age on which all other endeavors depend.
The modern electrical power grid is designed and managed to operate 99.9% of the time with less than a 2% variance in voltage, regardless of the load swings placed on the system.
When we wake in the morning we turn on our lights, radio, and coffee pot and get ready for the day. Before we get to our places of work, they turn on lights and increase heating or cooling loads to bring temperatures to comfortable levels. Air compressors, assembly line drives, computers, and other industrial machines by the millions fire up almost in unison, all fed by electricity taken from the grid.
On a typical day, a major city will increase load demand on its power plants by more than a million kilowatts, it will happen within a couple of hours, and it has to happen with perfection.
To accomplish this engineering feat, every generator (and there are many) involved with the grid must operate in harmony with the others.
Large steam driven power plants provide base load, or the large, steady portion of the electrical load that is most predictable.
Smaller generators, often gas turbines, can be started with the flick of a switch to pick up load increases.
The two essential components of all generators on the power grid are dispatchability and reliability. Wind power, as it is applied today, offers neither.
Dispatchability means that generators can be started when operators need them, any time day or night, regardless of weather conditions. Wind power isn’t completely dispatchable; it can’t be started unless the wind is blowing.
Reliability means that a generator will, virtually every time it’s fired up, produce constant, controllable power exactly as required by the power plant operator.
Wind power also fails the reliability test because, even when the wind is blowing, it rarely blows at a constant speed. Wind tends to blow in gusts with an ebb and flow that makes wind generated power difficult to control.
So, according to anti-wind groups, even when wind generators are running, power companies not only find themselves unable to reduce load to any appreciable degree, but they often find that wind generators sometimes cause more load swings than would otherwise occur. And generators that could have been shut down must continue running to accommodate the load swings.
Wind power advocates state that all electrical power grids have loads that vary from second to second. They have those variances without wind power. On average, wind turbines haven’t increased grid variances by much, if any.
Wind power advocates also say that concerns over reliability are overstated. While it is true that wind turbines can’t be started at the flick of a switch unless the wind is blowing, they often prove to be a surprisingly reliable and steady energy source.
The electrical grid system works not because every piece of equipment is one hundred percent reliable, but because there are hundreds of components with a large amount of reserve output capability (back-up) that work together to form one, very large, reliable system.
Still, there are pros and cons of wind power reliability. These reliability issues translate into cost concerns and become more pronounced as the number of wind turbines on a grid increase.
PROS AND CONS OF WIND POWER COST
Wind power advocates tell us that new wind turbines are highly competitive and cost less than nuclear power, which claims to be the cheapest electrical energy resource known.
But anti-wind power groups state that the cost per megawatt of installed capacity doesn’t begin to tell the whole story. Wind power, because of the problems discussed above and more, will continue to have a cost disadvantage.
At first glance it would seem that a simple wind generator would be cheap to build. But reality has shown that simple isn’t necessarily cheap.
Money saved because wind turbines don’t need steam or other engines to drive them is spent on huge, surprisingly high tech, propellers and gearboxes.
Wind turbines don’t need boilers or reactors, but they do need expensive, and again surprisingly high tech, towers and electronic control systems.
And wind turbines don’t need expensive fuel to operate but they often occupy relatively large landmasses that are paid for with rent payments from every kilowatt generated.
Then there are the reliability and dispatchability problems discussed above.
On average, wind generators operate with a
of about 30%. Because the wind doesn’t blow all the time and it doesn’t blow at a constant rate when it does blow, a one-megawatt wind generator can be expected to actually generate only about 300 kilowatts of power per hour averaged over the course of a year.
So, if we want one-megawatt of reliable and dispatchable power from a wind generated power supply we will probably need over three-megawatts of power producing wind turbines installed. We will also need a means of
Grid Energy Storage
like batteries or hydrogen to save excess energy generated on windy days to use when there is no wind.
The amount of storage medium needed depends mainly on a combination of the Capacity Factor and the percentage of power supplied by wind generation.
As it is applied today, wind generation provides less than 1% of grid demand and requires no energy storage. All of the power generated by the wind is consumed.
How much energy can we realistically expect to generate from wind? It turns out to be about 20% of demand on a given electrical grid.
As wind generated energy levels on a typical grid exceed about 20% of grid demand, the economics of wind power change rapidly and the cost to add additional wind generating capacity increases as the percentage of wind power on the grid increases.
As more wind turbines are added above the 20% level, the load swings from varying winds become more significant. To reduce these load swings more turbines per megawatt of wind power produced and more storage medium are needed.
Reliability and dispatchability issues could add up to a large scale system that cost over 400% more per megawatt than the cost of a one-megawatt wind generator.
And anti-wind groups are quick to point out that there are yet more problems with wind power.
PROS AND CONS OF WIND POWER AVAILABILITY
Wind is widely distributed but it is also area specific. There are a large number of areas with economically usable wind sites. But the best wind sites are often located in sparsely populated areas, far away from the population centers they need to serve.
The problem with these remote locations is that wind generators placed there will require miles of extra transmission lines and will suffer reduced efficiencies from transmission losses. These problems can be overcome but they add yet more cost to wind power.
PROS AND CONS OF WIND POWER AESTHETICS
Some look at wind generators and see things of beauty. But others see scarred landscapes with noisy wind machines that continue polluting the scenery at night with aviation strobe lights endlessly flickering and flickering and flickering.
While one wind machine might not be a problem; many believe that the million plus wind generators that would be needed to replace existing power generators would create a nightmare landscape from one end of the country to the other.
But wind power advocates correctly state that a huge amount of our energy needs can be supplied from offshore and mountaintop wind generators that will be out of sight of almost everyone.
The pros and cons of wind power aesthetics is a hot point of contention in a number of communities. Don't be surprised if this one issue creates more lawsuits than all of the others combined.
PROS AND CONS OF WIND POWER SUSTAINABILITY
Of course, none of the other pros and cons of wind power matter if we don’t have enough wind to supply adequate energy to civilization.
A number of studies have been done and while estimates vary from one study to another, all of the studies agree on one thing; we have far more wind power available than we will likely ever need.
Stanford University Wind Power Study
gives us the following numbers.
Total annual global Btu consumption: 7,000-10,000 Mtoe
Total global economically feasible wind generation capacity: 54,000 Mtoe
Btu: British thermal unit; the amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
Mtoe: Million metric tons of oil equivalent; or about 7 million barrels of oil (42 U.S. gallons per barrel); or 11.63 TWh; or 40 Trillion Btus.
TWh: Terrawatt hours – One million Megawatt hours, or one billion kilowatt hours, or about 3.44 Trillion Btus.
All of that data adds up to economically feasible wind generation capacity of over 40 times current electrical demand, and about 7 times total current Btu demand from all energy resources including electrical generation.
The Stanford study is probably the most detailed wind resources study to date. If you click the link you will find maps that show the locations of wind resources over the entire world.
AEWA Wind Resources Data
shows annual global wind resources that translate to about 142,500 Mtoe annually. That amounts to 15 times global annual energy demand.
The main reason for the difference between the AEWA figure and the Stanford figure above is that the AEWA figure reflects total theoretical capacity, whereas the Stanford number represents only wind speeds and volumes that can be economically utilized using existing wind generating technology.
By the way, the AWEA site also contains a discussion of the pros and cons of wind power and attempts to answer a number of concerns.
U.S. Department of Energy Wind Resource Maps
show details of wind resources throughout the United States.
Another good resource is the
U.S. National Renewable Energy Laboratory Wind Resource Atlas of the United States
Though there are a number of pros and cons of wind power, it looks very promising.
But is wind THE power source of the future?
Before deciding, you may want to read about the rest of our available resources.
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