This chapter, “Carbon-Free Energy,” introduces a wide array of sources, some of which produce little or no carbon dioxide, discusses their importance in terms of climate change and environmental impact, and describes the global efforts and agreements for their proliferation. First, there is the definition of what carbon-free energy is, coupled with the description of the environmental effect of fossil fuels, and considered the main contributor to greenhouse gases and climate change. It then goes to geopolitical considerations in energy production, underlining the very unbalanced geographical distribution of fossil fuel resources and further possibilities of conflict over its control. Further, the paper classifies carbon-free energy sources, focusing on renewable resources like solar, wind, hydro, geothermal, and biomass. Solar energy-photovoltaic and concentrating solar power-is recognized for its potential in directly converting sunlight into electricity with no carbon dioxide emission. Wind energy harnesses the kinetic energy generated by the wind and, for some time now, has been developing rapidly and becoming increasingly cost-efficient. Hydropower uses gravity's potential energy as captured in water flow to provide a reliable and stable source of carbon-free electricity. Other contributors reviewed to play an imperative role in the carbon-free energy mix include geothermal energy, harnessed from the Earth's internal heat, and biomass, derived from organic material. This chapter underlines that measures to tackle climate change and reduce impacts on the environment through the adoption of carbon-free energy sources require international cooperation, underlining the role of global efforts and agreements in driving this transition. The chapter also concludes by highlighting that carbon-free energy is at the core in making a sustainable future, while further challenges must be conquered to result in a decarbonized energy system.