This chapter examines global energy transitions as long, uneven, and power-laden transformations rather than clean technological swaps. Tracing successive shifts from biomass economies to coal-driven industrialization, petroleum modernity, and the contested rise of nuclear power, it shows how each regime reorganized labor, production, urban form, and geopolitical authority while expanding the scale of ecological disruption. This chapter highlights that energy transitions have always been embedded in wider histories of imperial extraction, war, and capitalist expansion, producing durable inequalities in energy access, environmental risk, and economic opportunity between and within regions. Against this backdrop, the contemporary renewable transition is analyzed as both a decisive break with fossil fuel dependence and a continuation of historical tensions around land, minerals, finance, and governance. This chapter argues that decarbonization alone is insufficient: without deliberate attention to justice, today’s transition can replicate older patterns of enclosure, sacrifice zones, and dependency in the Global South. Drawing on energy justice and political ecology perspectives, it identifies the conditions under which renewables can deliver not only lower emissions but also democratic control, fair distribution of benefits and burdens, and protection for vulnerable communities. By linking past energy regimes to present policy dilemmas, this chapter provides a critical framework for understanding energy transition as a socio-ecological reordering whose outcomes will be determined as much by institutions and power as by technology.