Energy equity refers to the distribution of costs and benefits of the energy power system. The energy literature engages with the issue of equity through the concept of energy justice . The latter concept itself is highly contested and could have diverse meanings for various stakeholders . In the broader sense, energy justice seeks to integrate justice principles, fairness, and social equity into energy systems . It does so by evaluating where injustices occur, who gets to bear the injustices, what process are there to remedy the injustices, and how the injustices can be eliminated [10, 20].
The current energy justice scholarship summarizes these principles under the four core tenets of energy justice: distributive justice, recognition justice, procedural justice, and restorative justice [10, 19, 20, 24, 25]. Distributive justice involves asking the question—where are the injustices? In general, this is the practice of embedding justice in the siting of energy infrastructure and the distribution of economic benefits and burdens . Studies of energy insecurity and poverty highlight the distributional burden of rising energy prices [26•]. These injustices are analytically examined through the affordability and availability principles, which will be discussed further in the next section. The recognition justice tenet focuses on considering who in society is ignored or misrepresented in the energy system . It helps expose the unfair proximity of vulnerable groups—ethnic minorities or indigenous peoples, to power plants and the unfair share of energy insecurity among the disabled and aging population . The third tenet, procedural justice, is about equity as public participation through the notions of transparency, accountability, and due process . Just outcomes are envisioned here by encouraging local knowledge mobilization, community engagement, and increased informational disclosure . The last tenet, restorative justice, which is the least studied in the literature, is about the response to those impacted by the inequities of energy systems by advancing the sustainability and responsibility principles . The sustainability and responsibility principles are based on the notion that energy resources should not be depleted too quickly and that all nations ought to protect the social and natural environment and minimize energy-related threats . Advancing these two principles, restorative justice ensures an equitable repair to the harm done on people and the environment.
For these reasons, the clean energy transition may deepen certain existing inequitable outcomes on different socio-economic groups, racial and ethnic minorities, genders, geographics, and other demographics [9, 15••, 29]. Energy storage could address the aforementioned justice tenets and support a more equitable low-carbon energy transition [3••].
Tenet 1 Distributive Justice
Availability and affordability of energy systems and services are key to realizing distributive equity [15••]. Availability as an equity principle affirms that people should have sufficient, reliable, and quality access to energy systems. Similarly, the affordability principle affirms that low-income and other vulnerable communities need financial as well as physical access to make use of available energy systems.
In the USA, low-income households spend a high percentage of their income (approximately three times higher) on energy cost compared to their mid-high income household counterparts [26•]. This is further exacerbated among those that face an added systemic inequity due to race, gender, disability, and age [27, 30]. For example, people with disabilities might have an increased energy cost in the summer because they need their homes to be cooler throughout the day . Similarly, the elderly population requires a narrower temperature range to maintain their health, increasing their energy vulnerability . Energy insecurity or bearing the energy burden could often lead households into critical stress, fear, and mental health issues. According to the EIA, in 2015, 17 million households faced an energy disconnection notice . Due to the COVID-19 pandemic, households have faced substantial energy burdens that can increase their vulnerabilities to the virus, psychological fatigue, and the potential loss of electricity due to non-payment as utility shutoff moratoriums come to an end [14, 32].
Another way to look at equity is by examining the accessibility of energy technologies across the socio-economic spectrum . Tax credit–based incentives are not as favorable for communities that have low or no tax liability . Financial structures that require high upfront costs or tolerance for extended payback periods, such as production incentives, will favor wealthier communities or businesses . Renters, who do not control rooftops, and multifamily environments where electricity costs are typically not paid by property owners, create split incentive challenges for efficiency and rooftop solar installations. In contrast, rooftop solar has been available for over a decade for those who can afford the system and those with owner-occupied single-family housing .
As energy storage solutions become downscaled modular and available to energy consumers on a behind-the-meter basis , it may follow the same path as distributed solar installations and offer higher reliability and lower energy cost to individuals with disposable income. Storage installations could however be scaled and sited intentionally to address these inequities. Energy storage solutions could provide the means to reduce energy burden by curbing expensive demand charges, supporting community-serving facilities, and lowering energy costs to affordable housing residents [3••]. Localized storage deployments, or even an increased penetration in storage capacity, could replace fossil-fueled peaker plants that are often sited close to vulnerable communities [3••, 35]. An example is PG&E’s Oakland Clean Energy Initiative (OCEI) plan to replace an old fossil fuel power plant with clean energy solutions, energy storage, and electric system upgrades to empower local communities .
In relation to availability, storage supports grid reliability and resilience in response to natural disasters and other disruptions that require backup power . To expand the distributive equity benefits of storage, incentives for storage deployment could target households that cannot access low-carbon energy systems and mitigate the inequitable distribution of clean energy technologies and benefits. For example, the California Public Utilities Commission (CPUC) runs a Self-Generation Incentive Program (SGIP) that offers energy storage rebates for homes, apartments, and critical facilities . The CPUC authorized a $1 billion funding through 2024 for the SGIP with part of the prioritization being towards low-income and medically vulnerable customers. In addition, the SGIP provides higher rebates under the categories of “Equity” and “Equity Resiliency” lowering the cost of energy storage to almost free of cost to low-income households.
Tenet 2 Recognition Justice and Tenet 3 Procedural Justice
For both recognition and procedural justice tenets, the assessment is on the processes of public participation: due process, representation, citizen engagement, and community consultation .
Recognition equity states that individuals must be fairly represented, and it reflects upon who exactly to focus on when thinking of energy victims [9, 20]. This tenet is critical for energy equity as it provides for the designation of specific solutions to address injustices. It asks the question, who is ignored? The answer identifies the sections of society that will be impacted or left behind in the transition. Minorities and indigenous people bear a disproportionate burden in energy production and power plant siting processes . Indigenous peoples especially bear the misrecognition burden due to their reliance on land and resources that get impacted by extractive industries . This inequity highlights the role of non-representation or non-inclusion of communities in the decision-making process, which points to the procedural equity tenet.
Procedural equity deals with the fairness of the decision-making process. Energy decision-making processes are highly complex. While there is a strong principle of third-party participation in the energy system, as captured for example in the Public Utility Regulatory Policies Act (PURPA) and the Open Access Transmission Tariff (OATT), or in independent market environments, participation still requires significant legal, financial, and engineering sophistication. To achieve procedural equity, decision-making requires full participation, adequate information, complete expression of opinion, and the impartiality of decision-makers.
The business model of aggregation of distributed energy resources is based on the integration of renewables onto the grid, in part spurred by storage systems’ potential to serve larger grid functions . Energy system planning, on the other hand, is either held by utilities with obligations to serve and availability of rate-based investments with least-cost principles  or by entities concerned with grid-scale reliability. Siting practices are highly fractured based on fuel type and scale. For example, the Federal Energy Regulatory Commission (FERC) permits and oversees hydroelectric projects, Nuclear Regulatory Commission (NRC) permits nuclear projects, but states or counties will permit natural gas plants, wind, and solar projects depending on the size. Siting processes are initiated by independent operators and developers in response to financial and physical/fuel conditions, and so siting processes are standards driven and reactive.
Energy storage planning and siting could be executed in a way that advances recognition and procedural energy equity. Continued progress in battery storage research and development has increased the efficiency and safety of storage systems making them fairly attractive . Through an inclusive energy decision-making process, states would be able to identify underserved and affected communities and design energy storage deployment mandates or consumer-based incentives to install storage to benefit those communities [3••]. This flips the idea that siting disproportionately harms indigenous populations, low-income communities, rural households, to one where local installation improves energy reliability and lowers costs.
As distributed energy resources (DER) transform the energy independence of communities, storage is a key enabler in the business model. Smaller grids with renewable resource-driven technologies are subject to more volatility without the ability to mitigate across a larger grid. Typically, this is managed with a dispatchable scalable resource such as a diesel generator. Storage is essential to maintaining non-emitting small grids, protection from fuel price spikes and supply chain shortages, while supporting independent renewable resource-driven systems . These attributes can provide health, wealth, and financial protections that benefit vulnerable communities.
Storage business models that advance community wealth also have implications for recognition and procedural equity, consider implementation of community energy storage systems (CES) . CES is an energy storage system designed with a community ownership and governance approach to generate socio-economic benefits. It is perceived as an intermediate solution between behind-the-meter storage systems and utility-scale distributed energy storage. The benefits of CES could be through an increased penetration of RE, the reduction in emissions, reduced energy bills, and the opportunity to generate revenue. Energy equity could be enhanced by strategically supporting the siting of CES in communities recognized as being impacted or regarded as underserved by the energy system. This could be done through co-ownership of storage assets with utilities or by subsidizing loans to low-income households to partake in CES.
Currently, there are two pathways for CES development—local and virtual . A local CES exists in a specific physical territory within a local community. The members of the community could engage in CES development for energy independence, resilience, and energy security and they can own and self-govern the system. In the virtual CES business model, the participating communities would not need to be a specific local community. Participants in this pathway would be members who form virtual communities and use the CES to provide energy services on an aggregated basis. To advance the equity benefits of storage, States could enact incentive programs that aim to prioritize the preference of affected communities as sites for wealth-creating technologies, such as CES. For example, the California Energy Storage Initiative (SB 700) is designed to integrate revenue-generating systems in low-income and underserved communities . The proposed SB 700 requires utilities to use 25% of the energy storage systems (ESS) money they receive in low-income neighborhoods and housing.
Tenet 4 Restorative Justice
Advancing restorative equity aims to repair the harm inflicted by energy systems [15••, 25]. All power plants have an economic and environmental footprint. Fossil fuel extraction and production industries cause pollution with air quality and water quality effects. These same attributes have health effects on local communities [17, 39]. Renewable energy resources have also raised questions about interactions in the siting process, around land use, avian species, and flicker effects, as well as supply chain sustainability [15••].
Applying restorative equity works to reverse and repair the harms done in such scenarios. Storage is facilitating the clean energy transition by allowing more renewable energy to come onto the grid while maintaining reliable operation . While it is not clear how much and what kind of storage is required for this trend to continue, storage will play a role in the continued grid-scale transition and consequent reductions in air emissions. In certain instances, storage can speed the total or incremental decommissioning of fossil fuel plants by allowing direct on-site replacement of power production in combination with other generators [3••]. However, it is crucial to proactively find solution to the potential inequities of storage in relation to scarce materials, working conditions for miners, and the disposal of batteries .