Lit Review · Gemini 3.5 Flash

**Introduction** A lot of literature on climate change mitigation and the transition to renewable energy has already been published. Most of the publications deal with international climate change agreements and especially large cities with a lot of financial power and center of interest. However, subnational actors are becoming more and more relevant for climate change research. An increasing number of mid-sized cities all over the world is contributing to the local energy transition. Although every single mid-sized city is smaller than a large metropolitan region with millions of inhabitants and a huge carbon print of municipalities, together they are home to a big part of the world’s urban population and their carbon prints as municipalities are significant. For this reason a closer look at renewable energy in these cities is important for the implementation of climate change mitigation on the national and global level. A first set of research on mid-sized cities focuses on the socio-technical and financial challenges for Renewable Energy (RE) in these specific urban forms. The studies on mid-sized cities compared to other types of cities have the potential to highlight the specific needs and challenges of mid-sized cities in terms of energy transitions. In a sense, also these studies are comparing cities, but in a different way. For example, a review on the financial and human resources that municipalities have at their disposal found that all types of cities have limited, chronic municipal resources. This review, however, also found that there is a huge need for support structures for medium-sized cities to transit from fossil fuels to RE. A second set of research on the topic of energy transitions in mid-sized cities surveys existing and emerging governance and policy tools and their implementation for RE in urban settings. The specific focus here is on the tools and practices that mid-sized cities are using for energy transitions, and in which ways these are different from, or even superior to, those in use by the largest metropolitan regions. The argument here is that the greater ‘agility’ possessed by mid-sized urban bureaucracies compared to the largest of metropolitan governments, the so-called ‘city forms in between’, enables them to implement rapid innovation around energy policy-and-practice more easily. An example of such practices and tools that are being reformed or implemented by these mid-sized cities are for example: 1) municipal utility re-form/ municipalization, 2) urban form-based zoning for RE, 3) distributed community scale solar power and other RE projects. A third set of research on the topic of energy transitions in mid-sized cities focuses on issues of social equity and ‘just transition’ to RE in these urban settings. These studies investigate how cities are dealing with the challenge of keeping costs for low-income individuals and households as low as possible during the transition to an urban form with low carbon emissions. The ways in which cities are dealing with these transitions and trying to keep costs down for low-income individuals and households, for example by providing relatively-cheap access to newly constructed energy efficient homes, or by lowering up-front costs for low-income individuals who want to invest in community-scale RE projects, are studied in detail. The review will focus on three areas within the literature on renewable energy in mid-sized cities. The first area consists of a list of socio-technical and financial barriers that in mid-sized cities need to be removed in order to give renewable energy a chance. These can consist of a lack of municipal funds, the absence of specialized technical staff in the municipal government, and limited access to financial resources in order to invest in green technologies such as wind turbines or solar panels. In addition, mid-sized cities have limited access to a range of financial instruments, such as green bonds. The second area consists of the various structures of governance and the repertoire of measures that in order to promote renewable energy at the municipal level exist. This can consist of municipal utility ownership and a range of measures that fall under the heading of zoning, such as community solar programs. The third area consists of the social equity or the ‘just transition’ of workers and their communities from carbon-intensive forms of production to low-carbon alternatives. The challenge that they pose for mid-sized cities is how to implement a just transition to renewable energy, in order to ensure that low-income populations are not unfairly burdened by the costs of the transition to renewable energy. By critically evaluating these three areas the review will highlight some of the main gaps in the current literature. The first gap consists of a marked imbalance in the amount of research that has been carried out on mid-sized cities in different parts of the world. The bulk of the research that has been conducted on ‘green cities’ has focused on a selection of pioneering eco-cities in Western and Northern Europe and North America, while there is a marked lack of research that has been conducted on eco-cities in the rest of the world.

Introduction As the world urgently seeks to curb climate change, the shift away from fossil fuels toward sustainable, renewable energy sources is speeding up. While a great deal of academic attention has previously concentrated on international accords and global cities with ample resources and governing clout, the current literature has begun to increasingly focus on the actions of the sub-national actors in this transition to sustainable energy. More specifically, mid-sized cities, those with 100,000 to 500,000 inhabitants, are an important setting for renewable energy adoption. These cities, though smaller than large, global cities individually, when aggregated hold a great proportion of the world’s urban population and contribute significantly to city-based carbon emissions. Hence, the transition towards renewables in mid-sized cities is a major topic of research as the need to achieve renewable adoption goals at the national and global level intensifies. This review provides an overview of existing research on renewable energy adoption in mid-sized cities, categorizing the themes of the literature into three areas. First, it reviews the socio-technical and economic challenges of energy transition in mid-sized cities. In particular, this literature emphasizes the limitations of these cities in comparison to global cities, such as a lack of funds, skills, and connections to finance large-scale renewable energy projects. Second, the review analyzes how the policies and governance practices of mid-sized cities impact renewable energy adoption. Research indicates that while these cities might lack some of the resources for energy transition that larger cities enjoy, the ability to quickly develop and enforce new legislation can be an advantage for these cities. Third, the review examines the literature on how equity and participation issues play out in the renewable energy transition in mid-sized cities. As this literature shows, mid-sized cities are attempting to ensure that a just transition takes place in which those who have least ability to pay are not burdened by energy transition projects. By examining the current literature on renewable energy in mid-sized cities, this review highlights several major topics that merit further investigation, including the geographic limitations of current case studies and a lack of quantitative comparisons of energy policy models in varying contexts. With these gaps in the literature in mind, the aim of this review is to produce a synthesis of the state of knowledge on renewable energy in mid-sized cities, and to serve as an entry point for those interested in exploring this important topic empirically.

Abstract: Humanity’s efforts to reduce greenhouse gas emissions and slow climate change have necessitated a major shift from fossil fuels to renewable energy technologies. Much of the research and policy focus on climate action and fossil fuel reduction has concentrated on international treaties and global cities as targets for change. However, global cities have massive budgets and bureaucratic structures that may not translate to smaller areas. Recently, there has been a focus on cities of medium populations and sizes (mid-sized cities) as units of analysis to study the “energy transition” at a local level. While mid-sized cities’ populations are dwarfed by that of global cities, they still make up a significant portion of urban populations worldwide and contribute to overall municipal emissions. As a result, it is important to take a closer look at how renewable technologies are adopted and implemented at the local scale. Therefore, this literature review will focus on renewable energy adoption in mid-sized cities and break down the scholarly conversation around this topic into three categories. First, it will focus on why these cities may face unique barriers to adopting renewables. Many mid-sized cities do not have the same level of resources as that of larger cities and can struggle with limited city budgets, lack of trained workers, and inability to fund projects through municipal green bonds. Next, it will highlight the policy levers that can allow these cities to transition to renewables. Things like municipal ownership of electric utilities, city-level zoning restrictions, and community solar allow for local control of energy transition. Current literature points to the fact that mid-sized cities may have less bureaucracy than larger urban centers which can allow for more rapid implementation of policies. This stream of literature will be juxtaposed with literature focused on equity. Finally, this paper will focus on how energy transitions can affect low-income households. As renewable energy technologies and energy transitions can be costly, mid-sized cities must be careful not to place that burden on lower-income families. By using these three categories as lenses, this literature review will not only summarize the current state of literature on renewable energy in mid-sized cities but find gaps in current literature. There are enough examples of renewable-forward cities in Western Europe and North America but not enough that focus on mid-sized cities in the global south. While there are case studies, literature that attempts to quantitatively determine which policy levers have the highest effect based on a region is still missing.

Introduction In response to the global need for carbon emission reductions, a worldwide paradigm shift from fossil fuels to renewable energy sources is under way. Whereas extensive attention has been dedicated to international frameworks and large megacities that, due to their considerable financial and bureaucratic resources, possess more leeway to innovate on the energy transition front, an evolving strand of the literature now brings to light the role of sub-national entities. To this end, mid-sized cities (cities with a population of between 100,000 and 500,000 people, for instance) have been singled out as prime sites where energy transition can and has to occur locally. Although smaller individually than metropolitan areas, mid-sized cities comprise a considerable portion of the total global urban population and are responsible for a significant amount of total municipal carbon emissions, making them an indispensable factor in national and international decarbonisation efforts. This literature review presents a synopsis of relevant scholarship and positions the main contributions within three prominent themes: 1) the unique socio-technical and financial obstacles mid-sized cities face in overcoming challenges to clean energy adoption. Compared to metropolitan areas, mid-sized cities are generally characterised by chronic resource constraints in terms of budgets, technical capacity and accessibility to green bonds; 2) governance structures and policy instruments that promote or inhibit energy transitions at the local level. A key point raised by many researchers is that the less bureaucratic structure and greater administrative flexibility of mid-sized municipalities can be translated into the rapid implementation of policies; and 3) social equity and citizen engagement in the process of transition to renewable energy. I focus on the 'just transition' and the efforts mid-sized cities have made to prevent certain segments of society from bearing an unjust share of the burden of new energy infrastructure. This literature review has several implications for future research; namely, that a geographically unbalanced sample (most of the studies reviewed focus on cities in Western Europe and North America) still requires addressing to bring a broader range of contexts and settings into account for future case studies of pioneering green cities. Likewise, this body of literature still suffers from a shortage of robust quantitative models that compare, in the case of varying geologies and political contexts, the effectiveness of various policy frameworks. In conclusion, the literature review aims to provide a synthesized overview of the state of research on renewable energy adoption in mid-sized cities and serve as a foundation for future empirical work to establish how this process can be carried out effectively.

**Introduction** There is a need for a global effort to reduce the reliance on fossil fuels. It has become evident that efforts to reduce reliance on fossil fuels must coincide with efforts to reduce the impact of climate change. In the past, most researchers have concentrated on the international climate policies and mega-cities that have the resources and administrative capabilities to develop solutions. However, a notable trend in the literature has shifted to include sub-national actors. Many of these actors are mid-sized cities. These cities become prominent settings for local energy transition activities. While mega cities are large in population and make a large impact on global emissions, mid-sized cities collectively account for a large part of the global population and a large fraction of global municipal carbon emissions. For these reasons, it is important to understand the situation and challenges of renewable energy in mid-sized cities if we are to meet the global and national targets for decarbonization. This literature review consolidates the research regarding renewable energy in mid-sized cities, organizing it into three sections. First, it investigates the social, technical, and financial challenges smaller cities experience. These cities have more constrained budgets and less access to smaller funding bodies, such as the green bonds. Second, it considers the policies and the bureaucratic structures, such as city/town ownership of utilities and local zoning and solar policies, that both aid and impede the transition to local energy. The bureaucracy of mid-sized cities is less rigid than that of large cities, and this can lead to quicker policy innovation. Third, the review focuses on the equity and engagement of the community, specifically how mid-sized cities work to ensure equity during the transition to renewables and that low income and marginalized groups are not left to carry the burden of the transition. This review relies on the critiques of the thematic areas to discover key gaps in the literature, including the fact that most case studies on leading green cities focus on Western Europe and North America, and that much less research has been done on mid-sized cities in the Global South, with even less case studies focusing on them. Also, there are no quantitative models that strive to discern how the same policy can yield greater or lesser results in different geopolitical areas. This review strives to present a clear summary of the existing knowledge in this area, in order to give researchers something on which to base theirwork in understanding how the mid-sized cities can grapple with the multi-faceted challenges of the renewable energy transition.

Introduction The climate action agenda has forced humanity to move quickly toward a world where reliance on fossil-fuels gives way for energy from renewable sources. Historically, scholarly work has either taken a big-picture view of international climate regimes or concentrated largely on megacities which command enormous wealth and centralisation capacities as a focal point for climate action.1 Recent literature has begun to highlight more decentralized sub-national actors. In particular, mid-sized cities (normally defined as urban zones of between 100 000 and 500 000 individuals) have become key playing fields for nearby energy progress. But while mid-sized cities tend to be smaller than metropolises, they represent a large proportion of the global urban population and also produce a significant amount of municipal carbon emissions. Therefore, it is critical to understand the drivers of renewable energy diffusion in these important urban settings to meet national and international decarbonisation targets. This integrating literature review synthesizes the existing scholarly understanding of renewable energy. First, it investigates the specific socio-technical and financial barriers these municipalities encounter. Mid-sized cities, in contrast to their bigger counterparts, often face almost permanent resource constraints in terms of limited municipal budgets, geophysical challenges such as slope stability and drainage management problems requiring high-tech solutions for climate resilience — compounded by lack of tech-specialist capacity and expertise at all levels with regard to designing systems for guidance on adaptation investment criteria within the scope of an evolving climate action framework; finally needing yet limited access to green bond markets to fund them over medium-longer time-frames. Second, it examines the governance mechanisms and policy tools, like ownership of municipal utilities, local land-use regulations and community solar programs that support or deter local energy transitions. As some researchers come to emphasize, the nimbleness of mid-sized bureaucracies can help accelerate policy implementation compared with larger, less flexible metropolitan governments and lend a special advantage for innovation at speed. Finally, this review highlights the compelling intersection between social equity and citizen engagement by exploring how accountability structures in mid-size cities can help promote a "just transition" that does not pass on disproportionate costs of new energy infrastructure to low-income populations. Critically reviewing these thematic areas, this review highlights the key gaps of the literature. Importantly, though there is a wide variety of aaase studies on leading green North America and Western European cities, much of the geographic balance in this field remains heavily skewed to mid-sized Global South cities. Finally, this literature review highlights the absence of detailed quantitative models comparing the effectiveness of competing policy frameworks in a variety of geopolitical conditions. The overall goal of this review is to assemble a systematic synthesis of current evidence and identify key areas for future empirical research on how mid-sized cities can strategically advance through the increasingly complex achievement of the renewable energy transition.

Introduction Motivated by the exigencies of climate change mitigation, an accelerating global transition from fossil-fuel energy reliance to renewables is taking shape. Although much of the literature to date has focused on international treaties and the megacities that have the fiscal resources and centralised bureaucracy to deploy far-reaching energy solutions, a nice trend in the literature is the growing perception of the role of sub-national actors, in particular medium-sized cities (typically cities of 100,000 to 500,000 populations) face a major role in the national and global transition. While smaller than metropolises, these medium-sized cities are where the bulk of the urban population reside, and constitute a large share of total municipal carbon emissions. It is important to understand the locus of renewable energy transition within the urban settings of their application for national and international decarbonization. This literature review summarizes the literature on that topic, clustering the study of the subject into three themes. The first examines the socio-technical and financial aspects of the sceptre and idiosyncratic barriers they face. Surrounded by target-rich environment, choked by chronic resource deprivation and budget deficits, clogged by a lack of available expertise, and cut off from use of the green bond markets (especially in developing nations), medium-sized cities face different barriers to making renewables work for them, than large metropolitan cities. Second is the subject of governance, utilitary community zoning and solar policies and how the idiosyncrasies of the medium size city lends it adaptability of more frictionless and rapid transition politics than the resulting agonistic paralysis of mega metropolitan city governments pursuing attention-seeking policies. Lastly, we hone in on the neglected subject of social justice and citizen participation, how medium-sized cities engage with and protect indigent peoples from exploitation in the new energy normal. In our survey, we identify a number of large gaps in the literature examining medium-sized cities in the only indigenous, wholly place-based ecopolitical transition subjects we have cited. These include the disproportionate amount of research in “pioneer green cities” in western Europe and North America but almost none across the globe in Global South mid-sized cities, and a dearth of quantitative models comparing differing policy models across multiple geopolocations. These gaps will persevere with emphasis on similar normative cities. In the rebirth for the good of collected humanity will likely reside. We seek herein to weave together a cloth quilt from the fabric of all these dark cotton-picking patches.

**Introduction** In line with the world's efforts to combat climate change, there has been an increasing trend toward energy transition. In spite of the existing literature on international climate policies and megacities (which have substantial capital reserves and strong bureaucratic capabilities), there has been a recent paradigm shift in terms of focusing on sub-national entities. Mid-sized cities, which are characterized as urban settlements with a population ranging between 100,000 and 500,000, have become focal points of attention. These urban communities make up a considerable part of the global urban population and contribute significantly to the city-wide emissions of carbon dioxide. Hence, gaining insights into the dynamics of adopting renewable energy in these specific cities is important to achieve the ultimate goal of global energy transformation. This literature review will consider the recent developments in research on the process of adoption of renewable energy in mid-sized cities through examining three main areas of interest. First, the peculiar challenges that these urban communities face will be addressed, as they involve socio-technical barriers and financial limitations. Second, the topic of governance and policy design will be covered to evaluate how specific policy-making and governance structures influence or impede local energy transition processes. Third, issues relating to social equity and citizenship will be discussed, since it is essential to find ways to ensure that low-income groups do not bear the brunt of any expenses associated with the adoption of green energy. By addressing these three focal points, this literature review will identify some gaps in the existing research, which need to be filled in by future scholars. Currently, there is a notable lack of geographical diversity in terms of the existing case studies on green cities, which tend to focus mainly on Western European and American examples. Furthermore, the existing body of research lacks comprehensive models aimed at comparing the efficiency of different policy frameworks. Thus, this paper attempts to provide a concise overview of the existing literature and set the foundation for further empirical studies.

** **Introduction** There is an increasing sense of urgency to address the global imperative to reduce greenhouse gas emissions associated with climate change through the widespread transition to renewable energy systems. The bulk of the prior scholarly focus has been on international agreements regarding climate change and mega-cities — which possess large financial resources and highly centralized bureaucratic capacity — however recent scholarly interest has shifted toward the role of subnational entities in addressing climate change. Mid-size cities (urban areas typically defined as having a population between 100,000 and 500,000) are emerging as critical spaces for transitioning to decentralized renewable energy. Although they may be smaller individually than mega-cities, mid-size cities together contain a sizeable proportion of the world's total urban population and produce a considerable portion of municipal CO2 emissions. Therefore, it is important to understand the ways in which renewable energy systems are being adopted by mid-size cities if broader national and global decarbonization goals are to be achieved. This literature review provides a synthesis of current research examining renewable energy system adoption by mid-size cities. In doing so, it organizes the academic discourse surrounding renewable energy system adoption in mid-size cities around three major themes. First, the literature review will explore the socio-technical and financial barriers that mid-size municipalities encounter relative to adopting renewable energy systems. Unlike their larger counterparts, mid-size municipalities commonly experience chronic resource limitations such as; limited municipal budgets, lack of experienced technical staff and limited ability to participate in green bond markets. Second, the review will examine the governance mechanisms and policy tools (for example; municipal utility ownership, local zoning regulations, community solar programs), that either enhance or constrain the ability of mid-size municipalities to undertake local energy transitions. Research indicates that the relatively agile nature of mid-size municipality bureaucracies can allow for more rapid policy development and implementation compared to those of their larger metropolitan government counterparts — providing a potential competitive advantage in terms of facilitating innovative practices. Thirdly, the literature review will consider the relationship between social equity and citizen engagement during the "just transition" process of implementing new energy infrastructure. It will investigate how mid-size cities have navigated issues related to ensuring that low income populations are not disproportionately harmed by increased costs associated with new energy infrastructure. Ultimately, by critically assessing each theme identified in this review, it will identify a number of significant gaps in the extant literature. Most notably, although numerous case studies exist documenting examples of pioneering green cities located throughout Western Europe and North America, there exists a significant geographic imbalance in terms of research focus — as there are very few studies investigating mid-size cities located in developing countries (the Global South). Moreover, there is currently no comprehensive quantitative model available that compares the effectiveness of various policy approaches employed at the municipal level across diverse geopolitical settings.

**Introduction** With the worldwide call to combat climate change, the switch from the dependence on fossil fuels to that of renewable energy sources has speed up. Although a large part of the scholarly work so far has concentrated on international climate frameworks or megacities with their financial means and centralized administration, recently this has shifted to a greater emphasis on sub national actors. In particular, medium-sized cities (usually those with 100,000 to 500,000 residents) have become critical locations for local energy transformative processes. While not as large as metropolises on their own, mid-sized cities can make up a large share of the global urban population and contribute a considerable amount of municipal carbon emissions. Therefore, understanding the dynamics of a renewable energy adoption process in these locations is key to reaching decarbonisation goals on the national and global levels. This literature review compiles recent research on renewable energies and their implementation in medium-sized cities into three main thematic areas and summarizes the discourse. It first looks at the particular social-technical and financial challenges that these municipalities are dealing with. Mid-sized cities, for example, are often faced with recurring challenges around a shortage of public funds, absent city technical capacity or limited access to green bond markets. Second, the review delves into municipal utility ownership, localized zoning, community solar and other governance structures and policy instruments that either enable or hamper local energy transitions. The relative agility of mid-sized bureaucracies is sometimes seen as a special area of opportunity for innovative implementation of policies that can be quicker than it is in larger, stiffer metropolitan government. Last but not least, this review deals with the close intersection of social equity and citizen engagement, examining and analysing to what extent the new energy infrastructures' costs will be borne disproportionately by low income groups and how mid-sized cities deal with this "just transition". This review examines these thematic areas in a critical manner, and reveals a number of areas where the literature is limited. Of particular concern is the geographic imbalance (ignoring the small local literature on exemplary green cities in western Europe and North America) and the lack of studies on mid-sized cities in the Global South. Further, the literature contains no general (quantitative) models to compare the effectiveness of the various types of policy regimes in different geopolitical settings. In conclusion, this review strives to integrate current understandings and thus supports a guide for future, empirical studies on successful renewables pathways in the context of mid-sized cities.

Introduction Renewables are advancing faster than ever due to the global call for climate action away from fossil-fuel reliance. In this respect, the literature that previously devoted considerable attention to international climate regimes and megacities endowed with substantial financial resources and de facto centralized decision-making has dramatically changed focus on a narrower range of sub-national actors. In particular, it is the case of medium-sized cities (which means urban areas with populations between 100k and 500k inhabitants) that have become critical laboratories for local energy transitions. Mid-sized cities, while individually smaller than metropolises represent a large share of urban population and greenhouse gases emissions from the municipal sector. Thus, studying the process of renewable energy development in such particular urban settings is essential for accomplishing national and global decarbonization targets. This literature review synthesizes existing studies on renewable energy adoption in mid-sized cities and organizes academic discussion into three main contemporary themes. This paper then reviews both socio-technical and financial barriers that impact these municipalities before going into detail on how each barrier can be solved or mitigated. In contrast to their larger peers, the financial resources of mid-sized cities are usually low and stretching municipal budgets is a long-time reality; they lack specialized technical skills as well as dedicated access to green bond markets. Second, the review examines local energy policies including municipal utility ownership structures and decision-making tools like localized zoning laws or community solar projects. It is becoming clear to researchers that the agility of mid-sized bureaucracies can enable quicker policy implementation than in large, cumbersome and tradition-bound metropolitan governments with ages old standard operating procedures—something requiring slow reform—but presenting a quick innovation advantage. Finally, this review explores the major nexus between social equity and citizen engagement in relation to how mid-sized cities may find a path through what some have termed "just transition," avoiding situations where low-income populations pay disproportionate costs of new energy infrastructure. This review identifies some gaps in the existing literature through a careful evaluation of these thematic areas. Importantly, we have more case studies of green cities not only in the Global North but also at national level on small/large city preventions and strategies (see antique position papers from Western European towns) surrounding a geographic empty brace towards mid-sized homes in the global south. Even the literature so far lacks quantifiable models systematically comparing how each kind of policy framework fairs across a variety of geopolitical landscapes. The overall objective of this review is to produce an integrated empirical overview that serves as a basis for future research on the role mid-sized cities can play in meeting the challenges presented by renewable energy transition.

Everyone’s talking about climate change, and honestly, the push to move from fossil fuels to renewables is speeding up fast. Most of the big articles and research out there used to zero in on global treaties or those giant megacities with deep pockets and powerful governments. But lately, the focus has shifted—people are paying more attention to mid-sized cities now. These towns, with populations between 100,000 and 500,000, fly under the radar compared to megacities. Yet together, they’re home to a huge chunk of the world’s city dwellers and are serious contributors to urban carbon emissions. So, digging into how these cities tackle renewable energy isn’t just interesting—it’s key if we actually want to hit national and global climate goals. This review pulls together what researchers are saying about renewables in mid-sized cities and breaks things down into three main themes. First up: the obstacles. These cities hit walls that bigger cities can sometimes dodge, like tight budgets, not enough experts on staff, and trouble tapping into financing tools like green bonds. Next, the policies and governance. The way these cities run things—whether it’s local ownership of utilities, zoning rules, or community solar projects—matters a lot for how well they switch to cleaner energy. Some studies even point out that mid-sized cities have more nimble governments, so they can roll out new ideas faster than the big-city bureaucracies. That flexibility isn’t something to overlook. Last but not least, there’s the people factor. Social equity and citizen engagement aren’t just buzzwords here. These cities need to make sure low-income communities aren’t left behind or paying the price as the energy system changes. Looking at all this, the review spots some big gaps, too. Tons of case studies come from Western Europe and North America, but there’s barely anything on mid-sized cities in the Global South. And when it comes to comparing different policies or modeling how they work in various places, there’s not much out there either. The goal here is simple: tie together what we know, highlight what we’re missing, and lay out a foundation for future research—so we can really figure out what works for mid-sized cities navigating the messy transition to renewable energy.

**Introduction** The global need to address climate change has sped up the shift from fossil fuel dependence to renewable energy sources. Historically, much research focused on international climate agreements and megacities, which have significant financial resources and centralized administration. However, there is now a critical shift in literature that highlights the role of sub-national actors. Mid-sized cities, defined as urban areas with populations between 100,000 and 500,000, have become important places for local energy transitions. While individually smaller than large cities, mid-sized cities together hold a significant portion of the global urban population and contribute a large share of municipal carbon emissions. Therefore, understanding how these cities adopt renewable energy is essential for meeting national and global decarbonization goals. This literature review brings together current research on renewable energy adoption in mid-sized cities, organizing the discussion into three main themes. First, it looks at the unique social, technical, and financial challenges these municipalities face. Unlike larger cities, mid-sized areas often deal with ongoing resource shortages. This includes limited municipal budgets, a lack of specialized technical skills, and restricted access to green bond markets. Second, the review investigates the governance structures and policy tools, such as municipal utility ownership, local zoning laws, and community solar projects, that either support or obstruct local energy transitions. Researchers increasingly show that mid-sized bureaucracies can sometimes implement policies more quickly than larger, more rigid metropolitan governments, which offers a unique advantage for rapid innovation. Finally, this review discusses the important link between social equity and citizen engagement, analyzing how mid-sized cities work towards a "just transition" to ensure that low-income populations do not face unfair burdens from the costs of new energy infrastructure. By critically assessing these themes, this review points out several key gaps in the current literature. While there are many case studies on innovative green cities in Western Europe and North America, there is a significant geographic imbalance. There is a lack of research focused on mid-sized cities in the Global South. Additionally, the literature does not provide thorough quantitative models that compare the effectiveness of different policy frameworks across various geopolitical settings. Ultimately, this review aims to present a clear synthesis of the current state of knowledge and offer a solid foundation for future empirical research into how mid-sized cities can effectively handle the challenges of the renewable energy transition.