Conversation so far:
Which type of petroleum is best for the motor vehicle industry
Liquified petroleum, also known as propane, remains as one of the top 3 motor fuels in the world.
For what reasons is liquified petroleum one of the top 3 motor fuels in the world
Propane is naturally occurring and nontoxic to ground soil and water. Propane is a clean-burning fuel that emits less greenhouse gases than coal and other fuels.
What country is the biggest supplier of liquified petroleum
The biggest suplier of liquified petroleum is Saudi Arabia, exporting 734.00 thousand barrels a day.
What amount of liquified petroleum is imported by the United States
The United States imports 141.00 thousand barrels of liquified petroleum per day.

Question: what other sources can we use instead
Self-contained rewrite: What other sources can we use instead of liquified petroleum