Which renewable source is not considered a sustainable technology?

Natural gas, while a fossil fuel that can be used to generate energy, is not considered a sustainable technology in the same way as other renewable sources. This is primarily due to its environmental impact and the fact that it is a finite resource. Although it burns cleaner than other fossil fuels, such as coal or oil, it still releases greenhouse gases and contributes to climate change when burned.

In contrast, options like wind, hydro, and biomass are categorized as renewable because they leverage natural processes that are continually replenished. Wind energy harnesses the kinetic energy of wind, hydro energy utilizes flowing water, and biomass derives energy from organic materials. These sources align more closely with sustainability principles, which prioritize minimizing environmental impacts and conserving resources for the long term.