Louisville Public Media ran a story on August 31 titled “Fossil fuels failed Kentucky utility customers during winter blackouts.” [Fossil fuels failed Kentucky utility customers during winter blackouts] The story centered on the failure of LG&E/KU to prevent rolling blackouts for its customers during Winter Storm Elliott.  However, the story missed a few very important facts.

To begin with, extreme weather has taught us that utilities need to be better prepared to prevent blackouts.  Blackouts can be deadly, and they are estimated to cost the U.S. economy $150 billion annually.  And there is no infallible source of electricity, especially during extreme circumstances.  

There have been a number of highly credible reports and lots of discussion about the increasing risk of blackouts in more than half the U.S., including Kentucky.  According to experts, these risks are due in large part to the premature retirement of coal-fired power plants, which are dispatchable, and the addition of wind and solar power, which are not dispatchable because they depend on weather conditions.  Reliability means keeping the lights on during relatively normal and predictable circumstances.  The U.S. has national standards for reliability, and utilities can be penalized if they fail to meet these standards.[1]  However, these standards need to be updated as the nation’s electricity mix changes.  In addition, not enough is being done to make sure the grid is resilient to more serious challenges, such as extreme and unpredictable weather.  The Federal Energy Regulatory Commission, which oversees the nation’s grid, has failed so far to establish adequate standards for resilience despite the impacts of extreme weather.    

The story suggests that coal-fired power plants are not dependable and, therefore, the way to avoid blackouts is to replace fossil-fuel power plants with wind and solar facilities.  However, this is simply wrong because it would make the grid less, not more, reliable.  The nation’s two largest grid operators – PJM (12 states plus part of Kentucky) and MISO (14 states plus another part of Kentucky) − assign “capacity values” to different electricity sources.  These values are calculated to show how relatively dependable each source is when electricity demand peaks, like it did during Elliott.  The higher the capacity value (which is expressed as a percentage), the more dependable the electricity source is.  The table below shows the capacity values these two grid operators use for reliability planning purposes.  The ranges mean that capacity values vary at different times of the year.  For example, PJM has proposed to assign capacity values of 86% for coal and 76% for natural gas during the winter when extreme weather and competition with other uses makes gas less dependable than coal for electricity generation.

PJM and MISO Capacity Values

Electricity SourceCapacity Value[2]
Coal86% − 92%
Natural gas76% – 97%
Wind9% − 40%
Solar2% − 45%

These capacity values show that traditional resources, including coal, are considerably more dependable than wind and solar.  Renewables will become more dependable over time as battery storage technology improves, but traditional sources will be needed for the foreseeable future to make sure the lights, heat and air conditioning stay on in Kentucky and other states.

The performance of different electricity sources during Elliott also demonstrates the value and dependability of coal.  In PJM, coal provided almost half of the additional electricity that was needed when Elliott peaked.  On the other hand, wind and solar were able to provide only 10% and 1%, respectively.  In MISO, coal provided more than one-third of the additional electricity.  Wind was able to provide approximately one-fourth, but solar was unable to generate any additional electricity.

Percentage of Additional Electricity Generated During Elliott

 CoalNatural gasWindSolar
PJM47% less than 2%10%1%

Moreover, coal provides many other reliability attributes such as fuel security, voltage control, frequency support and ramping.  Wind and solar do not provide these reliability attributes that are essential for the grid to operate reliably.

For more information, please visit: https://www.dependablepowerky.com/

[1]  The North American Electric Reliability Corporation (NERC) establishes reliability standards for planning and operating the North American bulk power system. NERC enforces approximately 100 reliability standards.

[2] Both MISO and PJM have proposed changes to their capacity values.  The values in the table include MISO’s current capacity values and PJM’s proposed capacity values. 

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