2.1. Introduction2.2. Life Cycle Assessment of Solar Photovoltaic System2.3. Life Cycle Assessment of Wind Energy System2.4. Life Cycle Assessment of Biofuels2.5. Life Cycle Assessment of Biogas2.6. Life Cycle Assessment of Hydropower Plants2.7. Life Cycle Assessment of Geothermal Power Plants2.8. Comparison With Conventional Systems2.9. Conclusions