PJM Interconnection, a transmission operator serving parts of the eastern United States, has published a report confirming that its system can remain reliable even with the addition of more natural gas and variable renewable energy sources.
However, the report also points out that increased reliance on any one type of electricity generation source brings resilience risks not accounted for under traditional reliability standards.
The report was published on Thursday, and serves to respond to questions asked about the effects of fuel diversity on grid reliability raised by PJM stakeholders — specifically, whether losing too many traditional energy resources such as coal and nuclear plants would negatively impact the PJM Interconnection system. Currently, the PJM Interconnection system is part of the Eastern Interconnection grid which operates transmission systems serving all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and the District of Columbia. In total, PJM serves 65 million people in the United States, and includes over 82,000 miles of transmission lines.
“Recent growth in the amount of natural gas-fired and renewable generation has raised questions about “fuel diversity” on the PJM Interconnection system,” the report opens. “Considering the retirement of coal-fired generation and to a lesser extent the threat of nuclear generation retirement, stakeholders have questioned whether the system is losing too many resources which historically have been referred to as “base load” generation capability and whether the system is — or could become — so dependent on natural gas or renewable resources that operational reliability is adversely impacted.”
The report does not attempt to analyze market or economic impacts of fuel diversity or address public policy issues. Rather, the authors of the paper focused on the reliability aspects of fuel mix diversity, including fuel security. Among the report’s key findings, PJM found that its expected near-term energy resource portfolio is among the highest-performing portfolios and “is well equipped to provide the generator reliability attributes.”
However, PJM’s future resource mix is likely to move in a direction where there is less coal and nuclear generation, and the authors found that generator reliability attributes of frequency response, reactive capability, and fuel assurance will decrease, but on the flip side, flexibility and ramping attributes will increase.
“This analysis underscores our responsibility to continue to operate the system reliably, and explore the role of resilience, the ability to tolerate unforeseen shocks and continue to deliver electricity,” said PJM CEO Andy Ott. “Different resources provide different reliability attributes, though new technology or regulations have the ability to improve those capabilities. PJM needs to work with stakeholders and the industry to determine whether markets and operation structures need to shift to make sure that necessary levels of generator reliability characteristics are maintained in future resource mixes.”
PJM’s research found that it would likely need to rely heavily on natural gas resource for operational reliability, and that there were situations in which the levels of renewable energy resources such as wind and solar could be too high for operational reliability. However, there were unassessed risks for too heavily relying on natural gas, as well — such as gas deliverability during polar vortex-type conditions, as well as uncertainties associated with economics and public policy.
What is interesting, however, is that PJM found that a more diverse fuel portfolio does not inherently create more reliability. Rather, the report concluded that “Certain resource blends that fall between the least and most diverse offer the greatest number of key generator reliability attributes.”
“An adequate level of diversity fosters flexibility and adaptability in mitigating risks associated with equipment failure, fuel price volatility, supply disruptions, extreme weather and other unforeseen system shocks.”
The report also referenced a previous PJM study which concluded that “the PJM system, with adequate transmission expansion and additional regulating reserves, will not have any significant issues operating with up to 30 percent of its energy provided by wind and solar generation.”