This course examines the energy systems that power society and explains how burning fossil fuels drives climate change and degrades air quality. Drawing on principles from physics and chemistry, the course explains how energy from primary sources is converted into forms society relies on, why fossil fuels became dominant, and why transitioning away from them is complex. The course covers non-fossil-fuel-based systems (solar, wind, nuclear, etc.) and weighs trade-offs among energy sources, including climate and air-quality impacts, cost, intermittency, land use, and materials demand. Quantitative problem-solving builds skills in interpreting energy, climate, and air-quality-related data, while news, policy, and research articles connect class discussions to current events and help evaluate claims often oversimplified in public discourse. Assignments include responses to discussion questions, quantitative problems, and conceptual questions. The course culminates in a project that investigates pathways toward a just transition of the U.S. electricity system that reduces greenhouse gas emissions and improves air quality and health for the communities most affected. Students who have completed LSCI 2700 Energy & Sustainability should not register for this course. This course is required for the Interdisciplinary Science major and minor, satisfies the Natural Sciences subject area for the Environmental Studies major, and satisfies the "subject by subject" course requirement for the Journalism + Design major.