Which of the following is NOT a renewable energy source recognized by LEED?

Natural gas is not considered a renewable energy source according to LEED guidelines. Renewable energy sources are those that are replenished naturally over a short time period and have minimal environmental impact during their use. Geothermal systems capture heat from the earth, wind turbines harness air movement, and hydropower utilizes water flow—all characteristics that align with the definition of renewable energy.

In contrast, natural gas is a fossil fuel derived from organic materials that have been subjected to heat and pressure over millions of years. While it is often recognized as a cleaner alternative to other fossil fuels, such as coal or oil, it does not regenerate on a human timescale and contributes to greenhouse gas emissions when burned for energy. Thus, within the context of LEED, natural gas does not meet the criteria for renewable energy.