Man's use of fossil fuels like coal, oil and natural gas provides most of the world's energy but contributes to environmental issues like pollution and climate change. Renewable energy sources such as solar, wind and hydropower are increasingly important as they don't pollute or deplete resources, though they have limitations in supply and costs. Nuclear power also provides large-scale energy without pollution, but nuclear waste storage is a challenge and accidents are a risk. Alternative fuels like hydrogen may eventually replace fossil fuels but require more development. Overall, balancing energy needs with environmental impacts requires transitioning to diverse, sustainable sources.