The electric grids operate to meet demand without interruption and at a steady frequency. A grid is incapable of storing electricity. So, all the suppliers of the electricity should be dispatchable. Dispatchable means the grid operator can have their suppliers increase or decrease their supply to meet demand. Wind and solar are NOT dispatchable. Wind speed is not under the control of anyone but nature. So, if wind dies, so will the supply of electricity. Sometimes, when the wind is blowing slowly or not at all, they make no power at all. Of course, when the sun doesn’t shine, (as is obvious, at night), solar cannot supply any electricity. Clouds can affect solar output of electricity too. The grid operator’s nightmare is when wind and/or solar abruptly cease generating any electricity due to abrupt changes in wind speed or loss of sunlight.
If you think that this does not happen, let us look at the performance data. The Department of Energy’s energy information agency (eia) has posted a number of pages to the performance of a number of sources of energy. They look at the rated capacity of the specific source and actual capacity. They call the latter the Capacity Factor. The chart below shows annual performance of selected sources from the year 2012 to the year of 2021—a ten-year performance period.
|ENERGY||2012||2021||AMERICA PUBLIC POWER 2022 ELECT GEN CAPACITY|
|RC MW/ CF%||RC MW/ CP%||MW|
|Combined cycle||217,938/ 52||277,646 / 54.4||548,420|
|WIND||49,458/ 31.8||123,938/ 34.6%||133,594|
|SOLAR PHOTO||1,527/ 20.4||51,047/ 24.6%||66,610|
|NUCLEAR||101,166/ 96.1||95,748/ 92.7%||103,240|
Data provided by eia, of the Department of Energy
The first columns are from eia data. The last (American Public etc.) is my inclusion to compare installed rated capacity.
Rated Capacity (RC)is that of the name plate—the manufacturers top performance.
Capacity Factor (CF) is electricity that the machines have actually produced in the named year with respect to the name plate capacity.
Total of all the wind turbines capacity in 2012 was 49,458 mega watts of rated capacity and the actual production from this group of wind turbines of 31.8% that equaled 31.8%X49,458 = 15,728MW. The 2021 performance from 123,938 accumulated turbine groups is the rated capacity of 34.6% that equaled 42,886MW.
The principle finding about wind turbines is that it they can only produce electricity about 1/3 of the time. Ten years of data show only a 2.8% improvement in the capacity factor. Not much progress.
Solar is even-worse producing electricity regularly than that of the wind turbines.
These two together in 2021 were only able to produce about 60 % of their combined rated capacity. However, there is no production from solar at night. And these percentages are not produced in a steady fashion, they range of 100 % to 0%.
What allows them to work is having back up capacity supplied mainly from natural gas turbines and nuclear reactors. When the wind slows down or stops blowing, the combined cycle natural gas turbines must be rev-ed up quickly to make up the loss of electrical supply to the grid.
The combined cycle natural gas turbine would be functioning at a CF of 85% if there were no wind or solar to cope with. Why aren’t these combined cycle units running at 85%? Most States have made laws that require wind and solar electricity, if available, must be used.
To the uninitiated, it looks like wind and solar energy are good buys. But they do not know that you must build backup capacity from coal, natural gas, or nuclear energy operated electrical generators. These back up costs are never discussed by the alarmist.
From a Manhattan Contrarian’s** posting comes a proposed law that should be enforced:
“The grid operator should seek only offers of power that are firm and reliable for some reasonable period, say 24 hours at a time. If you want to sell wind power to the grid operator, it’s then on you to also provide the mix of backup sources (could be fossil fuel power plants, could be batteries, could be whatever else you come up with) to make your offer reliable for the requisite period.
With that market structure, the wind, and solar operators themselves would be required to recognize and calculate the costs of the intermittency of their assets. The structure would also give those operators the incentive to reduce the costs of intermittency (that is, of backup and/or storage) to the extent they can.”
Incidentally in the chart I have noted the performance of nuclear. Nuclear is the real solution for powering the grid. Unfortunately, the low price of wind and solar, is making these nukes unprofitable. If the full cost of the wind and solar were required by the proposition stated above, then a real cost comparison could be made. The nuclear plants produce no CO2. The EU has been forced to put the nuclear in their laws that favor wind and solar.
Finally, if the natural gas turbines rated capacity does not compare with the American Public Power numbers it is that there are over 100,000 MW capacity in turbines that are there to maintain grid stability. They function as very quickly operated units to back up swings in the grid. Their CF is about 8%. To get rid of most of them would only come with removal of wind and solar.
If you read the American Public Power listing of capacity it shows wind just below the capacity of Natural Gas based power. Because they do not note the fact that only 1/3 that listing produces power, many readers will be led to believe that wind is a much bigger factor that it really is.
** sorry, cannot find where I picked this up, but I will keep looking and give it its link.
Finally, the natural gas turbines rated capacity does not compare with the American Public Power numbers it is that there are over 100,000 MW capacity in turbines that are there to maintain grid stability. They function as very quickly operated units to back up swings in the grid. Their CF is about 8%. To get rid of most of them would only come with removal of wind nsolar.