It is unrealistic to expect the world to 100% run on renewable energy. The infrastructure required for a complete transition is expensive and time consuming to implement. Renewable energy sources like solar & wind are intermittent & dependent on weather conditions which leads to fluctuations in supply. The storage & distribution of renewable energy on a large scale pose significant challenges. Some industries & regions heavily rely on non renewable sources like fossil fuels for their energy needs. Achieving a 100% renewable energy world would require substantial technological advancements, policy changes & global cooperation.