Among fossil fuels, which typically produces the most CO2 per unit of energy released?

• A. Natural gas
• B. Coal
• C. Oil
• D. Uranium

Answer: (B)

The amount of CO2 released for a given amount of energy depends on how much carbon is in the fuel and how efficiently that energy is produced. Natural gas has the lowest carbon content per energy because methane is hydrogen-rich, so burning it yields more water and less CO2. Oil contains more carbon than natural gas, so it emits more CO2 per unit energy. Coal carries the highest carbon content and, historically, power plants burning coal operate less efficiently, leading to the greatest CO2 per energy produced. Uranium isn’t a fossil fuel at all; it generates energy through nuclear fission with essentially no CO2 from the reaction itself, which is why it isn’t compared with fossil fuels in this context. So, coal typically produces the most CO2 per unit of energy released among fossil fuels.