Which energy source does not produce air pollution once in operation?

Which energy source does not produce air pollution once in operation?

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

Answer: (A)

The key idea is that air pollution during operation comes from burning fuels. Hydropower generates electricity without combustion, so it does not emit pollutants like sulfur dioxide, nitrogen oxides, or particulates during operation. In contrast, coal, oil, and natural gas rely on burning fuels, which releases CO2 and other pollutants. So hydropower has no direct air-polluting emissions while it’s generating power. (Note: there can be other environmental impacts related to dams and reservoirs, but those are not direct air emissions during operation.)

The key idea is that air pollution during operation comes from burning fuels. Hydropower generates electricity without combustion, so it does not emit pollutants like sulfur dioxide, nitrogen oxides, or particulates during operation. In contrast, coal, oil, and natural gas rely on burning fuels, which releases CO2 and other pollutants. So hydropower has no direct air-polluting emissions while it’s generating power. (Note: there can be other environmental impacts related to dams and reservoirs, but those are not direct air emissions during operation.)