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Coal Communications Kit - Grid Reliability
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Grid Reliability

Coal represented 39 percent of U.S. electricity generation in 2014, making it the largest of all energy sources (U.S. Energy Information Administration, 2015). As coal generation capacity continues to be challenged by growing environmental regulations, many experts question the future reliability of the U.S power grid.

Emission Rates

A reliable bulk power system is one that is able to meet generation needs despite various disturbances that would interrupt supply or availability of electricity generation. North American Electric Reliability Corporation (NERC) broadly divides reliability into two categories: adequacy and security. Adequacy reflects whether there is a sufficient capacity of resources to supply electricity demand. Security is defined as the ability to withstand “sudden, unexpected disruptions,” such as equipment failures or loss of system areas. Fuel diversity is pivotal to both adequacy and security. Backup resources must be in place to offset unforeseen events that would interrupt power generation from various units (North American Electric Reliability Corporation).

Reliability Challenges of Renewable and Other Sources

Generators, such as gas, solar, and wind, are served by real-time fuel delivery or intermittent weather, and must balance fuel sources with on-site storage capabilities to maintain reliability, survive sudden disruptions, and control costs (U.S. Energy Information Administration). Natural gas as a source of power generation is particularly restricted by pipeline capacity limitations in extreme winter weather conditions due to competition with entities feeding residential and industrial end-users. Additionally, equipment constraints from frozen instrumentation during extreme temperatures limit the dependability of natural gas as a principal fuel source (North American Electric Reliability Corporation, 2014). Power generation sourced from solar and wind resources are also limited by the real-time environmental conditions associated with each, as well as insufficient transmission infrastructure to areas with the best environmental conditions for generation (North American Electric Reliability Corporation, 2014).

Superiority of Coal

Coal as a fuel source has many advantages to aid in reliable generation of electricity, contributing to both adequacy and security of the bulk power system. For example, coal-fueled generating units are well understood due to years of use as a primary source of energy across the world, and infrastructure is currently in place to support generation from these existing units. A safety stock of coal may be easily stored at the plant site, eliminating concerns surrounding real-time delivery. The 2014 polar vortex and the subsequent spike in gas prices due to cold temperatures, and lack of supply, served as a primary example of the risks associated with a real time fuel delivery.

Conclusion

Overdependence on any single type of fuel creates a greater risk of disruptions to electric power generation, especially during extreme weather events.  Coal as a fuel source has many advantages to aid in reliable generation of electricity: on-site storage, years of documented use, and an abundance of domestically-sourced supply. Coal is a vital component of our nation’s overall generation mix to maintain a reliable power system.

Grid Reliability: Facebook Post

Grid reliability is all about fuel diversity and availability of backup resources, as they are inevitably needed. Coal is a vital component of our nation’s overall generation mix to maintain a reliable power system. 

Grid Reliability: Elevator Speech

Coal is the largest of all domestic energy sources (U.S. Energy Information Administration, 2015). While there are other energy resources, such as gas, solar, and wind, they are served by real-time fuel delivery or intermittent weather and must be balanced by fuel sources with on-site storage capabilities to maintain reliability, survive sudden disruptions, and control costs (U.S. Energy Information Administration).

  • Natural gas is particularly restricted by pipeline capacity limitations in extreme weather conditions as equipment constraints from frozen instrumentation during extreme temperatures limit the dependability of natural gas as a principal fuel source (North American Electric Reliability Corporation, 2014).
  • Solar and wind are both constrained by geographical and transmission limitations, as developers install systems in the most windy and sunny locations first (Helman, 2014).

By contrast, a safety buffer of coal may be easily stored at the plant site, eliminating concerns surrounding real-time delivery. In extreme weather conditions, particularly low temperatures, coal possesses the necessary characteristics to consistently meet electricity demand. Overdependence on any single fuel type creates a greater risk of disruptions to electric power generation, especially during extreme weather events. Coal is a vital component of our nation’s overall generation mix to maintain a reliable power system. 

Grid Reliability: Objections and Responses

Objection: Renewables and alternative energy resources will be available to replace retired coal generation going forward.
Response: The current bulk power system must be reconfigured to support increased use of renewable energy. Additional transmission capacity must be built and expanded to reach remote areas where many renewable resources are located. This timeline may not coincide with deadlines as currently proposed by the EPA. For example, a new high-voltage line has a lead time of 5-15 years. Additionally, the cost of this transmission expansion will be passed on to end-users. Also, renewable generation capacity cannot be counted-on to replace on-demand capacity to meet system needs. Unless replacement fossil capacity or nuclear capacity is built, grid reserve margins and therefore, reliability will be sacrificed.
Objection: Improvements to energy efficiency along with increased use of renewables will lessen demand in the future enough to offset reductions in fossil fuel generation.
Response: Projections by the EPA estimated that growth in energy demand would be more than offset by growth in energy efficiency, causing total energy demand to continue to shrink. The studies cited by the EPA were based on only 12 states’ data which don’t adequately represent the energy mix and demographics of the nation as a whole. Overall energy demand is separated from available peak-hour generating capacity, which is a main determinant of grid reliability.



 

 

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