Helping America Navigate a New Energy Reality

Wind Energy Realities

By on 21 Nov 2011 in commentary

(Note: Commentaries do not necessarily represent the position of ASPO-USA.)

Reasons for interest in electric power generation from wind are multifold. First, wind is a renewable energy source. It is not likely to deplete over time, which is not the case for oil, coal, and natural gas.

Second, wind electric power generators use no water, which is in declining supply in many places in the world.

Third, there are no atmospheric pollutants emitted during the operation of wind electric power generators. Here’s where simple thinking fails, because wind electric turbines require near 100 percent fossil fuel backup in order to provide electric power on demand, which the public requires.

Wind blows at variable speeds and sometimes not at all. The physics of wind electric power generation tell us that the electric output varies as the third power of the wind speed, so a factor of two difference in wind speed means a factor of eight difference in electric power generation. Small or no wind means no electric power generation.

The nameplate capacity of a wind electric generator is the maximum that it can produce, which is much higher than its average electrical output, because average wind speed is always less than the maximum wind speed that a wind turbine is designed for. In the best geographical regions for wind, the difference between wind turbine nameplate power and its average electric output is in the 30-40% range; elsewhere the average can be much less.

There are numerous examples of electric power from wind not being available when needed. For instance, in a “heat storm” in California in July 2006, the electric power system was strained due to the unusually high demand for electric power for air conditioning. At the time, the wind was blowing at low levels in the areas where wind turbines were located, so available wind power was well below rated capacity. Because the local electric power grid had enough reserve power, the grid did not fail, and wide-area blackouts were avoided. However, had wind accounted for a larger fraction of the local electrical grid capacity, blackouts would have occurred.

Low electric power production from wind has been a problem in Texas, which has an aggressive wind power program. In recent forecasts, the regional electric power authority determined that during hot summer demand periods, less than 10% of the state’s wind power capacity could be counted on as reliable.

The Pacific Northwest is another region with an aggressive wind program. The region’s experience is that when electric power is needed most, wind is either not blowing or only weakly available. For example, during the cold days of January 5 – 28, 2009, wind electric power generation in the region was virtually non-existent. The Bonneville Power Authority stated that over a full 56-week period, nearly a quarter of the time total wind generation was less than 3% of total wind electric nameplate capacity.

Consumers require electric power on-demand – power must be available when we want it. If electric power is to be available on-demand, the fact that wind power is variable means that there must always be ready backup power available for when the wind fades or dies. In other words, other power sources must be standing by, ready to quickly make up for declines in wind power. These backup options must be able to respond very quickly to wind variations if power-on-demand is to be maintained. Four options for providing backup are prominently discussed:

1) Dedicated fossil fuel power plants

2) An existing grid with significant reserve capacity

3) Long transmission lines to interconnect wind turbines in far-flung regions

4) Hydroelectric storage

Using dedicated fossil fuel power plants can result in a wind/fossil fuel generation complex that is “dispatchable,” providing power-on-demand. In this option, the fossil plant must “run hot” so it is able to quickly ramp up to make up for rapidly declining wind power. In utility jargon, that hot-running operation is called “spinning reserve” and it means that a small amount of fossil fuel is consumed even when the wind turbines are operating at their maximum rated output. Overall costs in this case are the capital and operating costs for both the wind electric generators and one or more backup fossil fuel plants plus the fossil fuel cost required to maintain the spinning reserve. In this option, wind is in effect acting as a fuel-saver for the fossil plant, because when wind electric power is being generated, less fossil fuel is consumed. Total electrical power costs for the combination are clearly much higher than for the wind turbines alone.

In this situation, the reduction in the generation of carbon dioxide and other emissions is not 100%, because fossil fuels are consumed to maintain the needed spinning reserve. The electric generation cost of the so-called backup power plant is less than that of the wind turbines, and since near 100 percent backup is required, the wind turbines represent added cost, making the resultant electric power from the combination more expensive than it would have been without the wind turbines. This is a losing proposition economically.

Another backup option utilizes fossil fuel generators already on the electric grid as backup. Many existing grids have significant fossil fuel electric generation in spinning reserve, ready to make up for the loss of electric power when winds subside. The costs of this backup option are similar or lower than the first option, and wind power is acting as a fuel saver for existing fossil fueled plants. Since the backbone of this method of operation is fossil fuel electric power generators, wind again is simply acting as a fuel saver. If fossil fuels remain inexpensive, the cost of fuel saving is small, but the overall costs for the combined system are much higher, because of the added cost of the wind turbines. This is also a losing proposition economically.

The bottom line is that important purported advantages of wind electric power are not what are often assumed.

PS. Consideration of long transmission lines and hydroelectric storage options are dealt with in our book, “The Impending World Energy Mess.” Note that the fuel saver story for wind also applies to electric power from solar cells.

Dr. Robert L. Hirsch, Ph.D. is a former senior energy program adviser for Science Applications International Corporation and is a Senior Energy Advisor at MISI and a consultant in energy, technology, and management. Hirsch has served on numerous advisory committees related to energy development, and he is the principal author of the report Peaking of World Oil Production: Impacts, Mitigation, and Risk Management, which was written for the United States Department of Energy.

5 Comments

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  1. Robert Spoley says:

    All this “green” power generation is economically false and will always result in the use of inefficient backup power generation as an excuse to be “politically correct”. This is is basically what your article points out. There is a way around this that is cheap, “green”, safe and will minimize a lot of the inefficient power generation currently in use or for future use. The answer is thorium reactors. They are safe, emitt no gamma rays, just alpha particles that are cheap to shield from, are non – fissionable and therefore can’t go to meltdown, are “scaleable” so can built anywhere thus eliminating the need for hugh, expensive power grids. One of the best qualaties is the half life of daughter elements is in general very short, many of which are in high demand in the medical industry. The U.S. has hugh stores of thorium alresdy mined. Net result is no carbon emmissions, no backup generation required, no waste disposal problems, no import concerns, elimination of most solar and wind farms and a vast increase in domestic power security. By the way, The Chinese put their first thorium reactor “on – line” this summer. We, on the other hand, have Solyndra and its associates.

    Robert J. Spoley

  2. Bill says:

    Fracking has released so much natural gas that wind is probably toast for a couple of decades. And why build all that ugly junk when one nuke can run an entire city for decades.

  3. cameron conacher says:

    A variety of sources can provide power; however, some sources are better able to provide core power ‘all the time’ while other sources are better at providing ‘peak power’ some of the time. Generally it is a cost/availability/quantity of power question(s) as to which category each source belongs to. Wind is still expensive (a Chinese source of supply for strong magnets), intermittent availability, and limited quantity; so it would qualify as peak load type power source.

  4. BR says:

    Dr. Hirsch – I wonder why you didn’t mention concentrating solar (with storage such as molten salt) as an option that can provide baseload power production from a renewable source. It also has the benefit over wind and solar PV in that it tends to mostly use 19th century technology so it avoids exotic materials, etc. Concentrating solar can probably provide decent baseload power for about a quarter of the United States (more if the grid is upgraded) and a quarter of Europe. The main downside to my knowledge is that it produces less in the winter, but in the southwest there’s less power demand in the winter anyway since cooling is more of a demand than heating.

    (This is of course setting aside peak oil and the issue of substitutability for oil, which of course neither wind nor solar provide.)

  5. Darel Preble says:

    The intermittent nature of ground solar and wind, as you point out, makes them inappropriate for the grid, if cost and reliability are consideration. California’s latest energy plan,
    http://www.ccst.us/publications/2011/2011energy.php
    out to 2050 envisions CA going 66% nuclear. Given their seismology and politics, that seems unlikely, although they apparently recognize that ground solar and wind cannot meet their RPS mandate, without major cost and reliability repercussions.

    Moving the solar panels to GEO, however, (Space Solar Power (SSP)), would collect 9.6 times more energy than panels on the ground. Most critically SSP is baseload energy – not randomly intermittent. For comparison, if we try to convert ground solar into baseload energy by cycling it through the lowest cost bulk energy storage(CAES) the arithmetic reveals that GEO solar can deliver 71 times more baseload energy than ground solar, or much more if you consider weather variability. SSP also generates nearly zero CO2. Fundamentally this is why space solar will eventually be the dominant energy on earth. Japan realizes this and, like China, is hard at work designing and building it. E.g. http://www.yomiuri.co.jp/dy/business/T110122002679.htm

    Great Expectations,
    Darel Preble,
    Executive Director
    Space Solar Power Institute

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