The cost of energy is affected by the type of energy in question. Propane occurs naturally and is considered a primary source of energy. Electricity is a secondary source of energy because it must be created by using another type of energy such as gas or coal. For this reason, propane cost less in most areas.
The cost of electricity and propane varies by region. Using a mathematical formal to figure the cost of use, propane is more economical choice if selling for less than $3.24 a gallon (as of 2010). If propane is more than this, electricity is the cheaper choice.
The use of any type of energy source affects the environment. Propane gas produces low levels of air contaminants. Electricity itself does not produce any air pollutants. However, the production of electricity produces varied amounts of pollution depending on the primary energy source used in production.