Observations of an Evolving Grid: Resilience and Equity Performance Metrics

There is a long history of measuring reliability through metrics, but traditional reliability measures do not address system resilience—the ability of the system to prepare for, adapt to, and recover from disruptions [9]. With increased weather anomalies due to climate change, both in strength and duration, and the potential for cyber threats to the system, the ability of the electricity grid to withstand these events and to recover if impacted has become an important area of interest [10••].

In addition to traditional reliability metrics, new metrics should capture the flexibility and resilience qualities of the grid. Developing the tools and methodologies necessary to monitor system resilience will enable regulators, utilities, and the public to increase the ability to avoid and recover from electricity system disruptions. While reliability has usually been measured on a utility system-wide basis, resilience is also concerned with localized parts of the grid [4••]. Some parts of the grid may be more resilient than others; some communities may have greater access to emergency services. Accordingly, uneven resilience conditions implicate the need for equity in metric expansion. To understand how the grid serves a community during and after a disruption and to understand where on the system additional investment is needed, it is important to access data at a more granular level [5, 7], which implicates the need for finer resolution data in metric expansion as well.

Energy equity recognizes that disadvantaged communities have been historically marginalized and overburdened by pollution and underinvestment in clean energy infrastructure and may lack access to energy-efficient housing or transportation electrification charging infrastructure [11]. Achieving energy equity requires intentionally designing systems, technologies, procedures, and policies for fair distribution of benefits in the energy system [12, 13]. Meeting these societal objectives requires descriptive analytics on specific populations to measure how energy system impacts are distributed.

The regulatory focus on energy equity increased in 2020, compared to previous decades [8, 14]. In the 1990s, equity issues related to access, cost, and energy burden began to receive widespread attention as an issue of climate justice and in 2013 were refined as the policy-oriented concepts of energy justice and equity [15]. The same electricity rate within the residential sector can have very different impacts depending on the individual household’s ability to pay the bills [16]. Furthermore, energy technologies and regulatory programs, especially those that rely on upfront customer payments, tend to accrue to customers on the higher end of the income range, ostensibly leaving low-income customers with fewer options and fewer programmatic benefits [17, 18]. Extreme weather events, especially those caused by climate change impacts, have illuminated climate vulnerabilities in marginalized and overburdened communities. There is disproportionate risk on those that do not have the ability to anticipate, cope with, and recover from adverse events [19]. Inequities in affordability, access, and vulnerability implicate the need to consider resilience in equity metrics development. Also, like resilience, energy equity metrics will likely require granular data that recognizes the energy system impacts down to the household level. These downscaled metrics are expected to include socioeconomic factors, factors outside the control of the utility, and factors informed by the stakeholders who are locally impacted [7••].

In this paper, we discuss resilience and equity metrics for measuring grid performance, focusing on their emerging trends and future outcomes. Then, with state policies and electric utility activities, we highlight current examples of resilience and equity coupling in grid planning to demonstrate the intertwined nature of these grid objectives.

Discussions around grid resilience have grown in prominence in recent years, primarily because of the need to address climate change and cyber security-related disruptive events. Resilience can be defined as the ability of the electricity system to “prepare for and adapt to changing conditions and withstand and recover rapidly from disruptions,” where disruptions include “deliberate attacks, accidents, or naturally occurring threats or incidents” [23]. Resilience expands on reliability by considering additional elements such as preparing for, operating through, and recovering from disruptions.

Although there are a number of possible electric power sector resilience metrics proposed in the literature, in practice, there is a lack of standardized resilience metrics because of limited industry standards for grid resilience [24‐27]. Translating metrics from the literature into practice is a key challenge partly because new metrics raise the need for measurement that covers connected, emerging objectives. In addition, resilience metrics often are context (location) and threat (event) specific, which makes it challenging to standardize [28]. At a high level, resilience metrics, at a minimum, consider two key characteristics [1, 4]

Energy equity is an increasingly prominent societal objective with emerging definitions and metrics. Poverty and income inequality can be associated with multiple aspects of electricity services [6, 13, 14, 40]. There are communities who have disproportionately borne the negative impacts of the electric system, such as long-duration and widespread outages and limited access to resources that mitigate the consequences of these outages [41‐43]. These communities include low-income, marginalized, and/or vulnerable groups, such as communities of color, tribal communities, and rural communities, as well as those who are vulnerable to electric costs and outages. Established energy justice tenets (Table 3) call for improving the energy system in light of these community and individual circumstances [44••, 45]. For metrics, this entails a shift toward more socioeconomic assessment that goes beyond traditional measures of affordability or cost-effectiveness [7••].

Traditional electricity system metrics describe measurement at a national, state-wide, utility service territory or customer class scale. In years past, reliability metrics measured the number and duration of outages over the entire system and did not look at localized impacts. Similarly, measurements of customer satisfaction would look at the experience of an entire customer class regardless of location or individual circumstances [46]. Emerging metrics will have to downscale measurements so that resilience and equity can be measured at a community scale or even individual customer scale (Fig. 1). This granular approach helps to identify the location of investments to enhance outcomes [53].

Typically, performance metrics are tied to specific operating or cost measurements so that performance can be objectively and accurately tracked [4••]. However, measurements based on a traditional benefit-cost analysis may have limited value in informing equity performance and decision-making. An equity metric might seek to measure the accessibility of a regulatory process to nontraditional community advocates or track energy burden that considers both electricity cost and household income. In emerging resilience metrics, combining operating or cost measurements with socioeconomic factors can achieve both equity and resilience goals and assist with community resilience goals as well. For example, a resilience metric could not only measure the ability of a portion of the grid to withstand disruption but also the distance within that portion of the grid a customer might need to travel to reach shelter or medical assistance.

To meet equity objectives, electricity operators should consider past harms and disparities in the electric system in order to prevent repeating them. This implies a transition from controllable operations and cost-focused metrics to consideration of uncontrollable socioeconomic factors. While this may necessarily imply that some emerging metrics are not measurable performance metrics, it also recognizes the greater societal factors that are implied from electricity service. These values may initially be represented by tracking metrics, rather than performance metrics in the traditional sense [47•].

Regulatory proceedings can be long, can cover complicated and detailed issues, and can require specialized legal representation, particularly in contested case dockets. As a result, over many decades, regulatory proceedings have tended to attract well-resourced or dedicated advocates to the exclusion of those wishing to represent less well-funded points of view or even individual customers. As the expected outcomes of our electricity system are downscaled and increasingly include equity considerations, regulatory processes should also be downscaled, adapt to be more accessible, and include more diverse voices and the voices of the local populations.