Which of the following is NOT a non-conventional (renewable) energy source As per your syllabus, ?

1. Coal is a fossil fuel — a conventional (traditional) energy source. 2. Non-conventional / renewable sources: solar, wind, tidal, geothermal, biogas, atomic. 3. Solar cookers, wind farms in Gujarat/Tamil Nadu, tidal power at Gulf of Kutch are examples. 4. Non-conventional sources are inexhaustible and pollution-free compared to fossil fuels. _Source: syllabus Social Science (Geography), Ch 5 "Minerals and Energy Resources", §5.4_