Propane is a byproduct, not a product.
Propane is cracked into propylene used for polypropylene(plastic). Ethane into polyethylene(plastic). Butane into Butadiene(synthetic rubber).
Propane is produced by cracking naptha which comes from oil. Propane is also produced by separating it from natural gas.
BTW, if you are paying $95/year tank rental, you are getting screwed.
To save money, you can use your kitchen range to partially heat your house. That is direct fired and 100% efficient. But that makes your windows fog up and raises the CO2 in your air. And you have to be careful that no carbon monoxide is being produced because that will kill you. Make sure the flame is blue with only a small amount of yellow at the tip of the flame.
I've had propane radiant heaters in the past, don't want to do that again. I'll use my wood stove instead.
Hmmmmm Suburban Propane?
I can't but help think that EPA mandates for using CORN as fuel has something to do with this. . .