Saturday, May 25, 2013

The Cost of Wind Part III

To understand more of why wind generated electricity is so costly, I would like to explain a little about wind and electrical demand. Some electrical demand is constant. That means that electricity is expected in the middle of the night as well as in the middle of the day. Take, for example, a refrigerator, some cooling is required in the middle of the night as well as during the daytime. Some businesses operate both day and night and use electricity all around the clock. For example, my neighborhood grocery may stay open all night. As evening progresses, people who have been awake watching television or working on their blog post decide that the time has come to go to bed. They turn off electrical devices or allow automatic processes to turn of devices and then head to the bedroom where they will sleep all night. They are still using some electricity such as a night lamp, an electrical powered alarm clock, and various electrical powered devices that continue to demand electricity.  Even when turned off,  a desk top computer will continue to draw electrical current.

Electrical demand at late night is still far less than it is during the daytime. In order to assure that electricity is available during night hours as well as during day hours, electrical companies seek out reliable generating sources that can be drawn on continuously for days at a time. These sources are called base load power sources. In the United States, much of the base load electricity is supplied by nuclear reactors because reactors are reliable and they produce electricity at low cost.

During the daytime, electrical demand rises. People wake up, turn on their coffee makers, turn on their stoves and other electrical devices and then drive off to work where they consume electricity as well. Daytime electricity rises from the low nighttime demand. This forms a sort of intermediate daytime plateau of electrical demand. Part of that plateau last five days a week while a lesser part extends over the entire seven day week. Finally, at some point of the day, electrical demand may begin to rise above the intermediate load. Sometimes it fluctuates and sometimes the demand rises constant for several hours or more. One example of extreme demand rise is summer demand of electricity for air conditioning. In the Southern part of the United States, summer days are hot and many become uncomfortable. Sometimes, summer days become so hot that they begin to jeopardize the lives of some people.

As the summer temperature rises, people begin to turn on their air conditioning, at the same time, in the Southern United States, including Texas, wind energy begins to drop so that wind is not simply a poor source of peak energy, but actually tends to decline just when peak energy is in demand. Summer air conditioning demand creates the highest peak electrical demand in the southern states including Texas. That demand may not decline at sundown, for example, in Texas the temperature may still reach well over one hundred after dark. This is extremely uncomfortable and may be dangerous for people with heart conditions, other health related conditions, and for the elderly. Since wind is so poorly matched to peak electricity, it is unlikely that summer peak electrical demand could be met by wind.

Renewable advocates argue that the summer inadequacy of wind could be compensated for by increasing solar electrical generating capacity, but to do so would form a further replication of a wind powered generating system, because the solar powered system is intended to do the same thing as a wind powered generating system.  In addition, solar powered generation peaks in electrical output about noon, but electrical demand increases in a typical Texas environment in late afternoon as electrical power from solar generators drop. Finally, electrical output from solar generators drops to zero well before night. Demand may still be high on hot summer days. Thus, hooking up solar and wind may not provide satisfactory electrical reliability. Further electrical generating systems may be required to fill in the gaps between the solar/wind system and consumer demand.

Wind generally generates more electricity at night than in the daytime, but consumer electrical demand is higher during the daytime than at night. It is clear then that a wind generated system is poorly matched to consumer demand for electricity. As I have demonstrated, matching wind generating electricity to consumer demand requires systems of electrical storage that are neither cheap or without problems. Even if wind could be brought to a reliability that is comparable to nuclear power, the cost of wind generated electricity would be prohibitive.

1 comment:

Steve Aplin said...

I just toured one of the four water treatment plants in Toronto. These plants all use electricity to move water through the system. At night, the electric-powered pumps push water to uphill reservoirs which gravity-feed the system for the big peak demand spikes in the morning and afternoon. Imagine if the grid were wind powered. Ever experience turning the water faucet and nothing happens? That sinking feeling would become quite commonplace in a wind-powered grid.


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