Which of the following is not a renewable source of energy?

• Wind, water, and tides are called renewable sources of energy these are replenished at a higher rate than they are consumed
• The sources of energy that are in use for long periods of time by humans and once finished cannot be replaced quickly are called non-renewable sources of energy. 
• Natural gas was formed when prehistoric plants and animals died and were gradually buried by layers of rock. 
• Therefore, natural gas is in limited amounts on earth and once burnt, it cannot be replenished easily. 

Therefore, Natural gas is not a renewable energy source.