Propane is sold and delivered in gallons, while natural gas is sold and delivered in cubic feet. Propane can easily be converted to cubic feet as well though. The cubic foot measurement unity pertains to both propane and natural gas in their vapor forms. One cubic foot of propane contains 2,516 BTU, while one cubic foot of natural gas contains only 1,030 BTU. With this information, it is is accurate to say propane contains over twice the usable energy content per cubic foot (2.44 times more). Using these numbers to compare energy values in a real-world scenario:
- 100,000 BTU/hr furnace will use about 97 cubic feet of natural gas (100,000 ÷ 1,030 = 97.1) in one hour
- 100,000 BTU/hr furnace will use about 40 cubic feet of propane (100,000 ÷ 2.516 = 39.7) in hour
The rates of local energy utilities and propane companies will differ and will need to be taken into consideration for accurate comparison. The compare the costs of these two fuels accurately, you must compare the energy value cost which can be obtained through local propane companies and utility companies. Propane companies will provide price per gallon, while utility companies will provide price per cubic foot. The availability of natural gas will most likely determine whether or not propane can be used because many cities will require you to use natural gas if your business or residence is within a certain mile radius of a natural gas line.
Total Cost Comparison
Unlike electricity, the cost comparison between propane and natural gas is much easier because they can be directly compared based on their individual BTU ratings. Because we know that natural gas contains approximately 1,030 BTU per cubic foot and propane contains 2,490 BTU per cubic foot, we can easily acquire the fuel’s cost per BTU for each and compare the differences in price for more realistic volumes.
For example, if we assume the cost of natural gas is $15.00 per 1,000 cubic feet, this means that $15.00 will purchase about 1.03 million BTU’s of energy. The equivalent in propane would be 11.26 gallons. At $2.50 per gallon of propane, the more cost effective energy solution would be natural gas. For propane to be a more cost effective energy solution, natural gas would need to be more than $28.00 per 1,000 cubic feet (provided the cost of propane is $2.50 per gallon).
When natural gas is discharged into the environment it is considered a greenhouse gas. Propane, on the other hand, when released into the atmosphere, is not toxic or damaging and will not do any harm to the environment. This means propane will not contribute to pollution in its unused state, while natural gas will. Because of this, propane is considered a green fuel before combustion and remains environmentally friendly even after it is used as well.
Although, due to the cleanliness of each fuel, the comparison of emissions of propane and natural gas is fairly insignificant. Both propane and natural gas are classified as alternative fuels for vehicles and each exemplify clean burning characteristics with minimal amounts of harmful emissions and toxins. Natural gas as a primary energy source is sometimes used for electricity generation while propane is not. Because propane and natural gas are considered environmentally friendly fuels, there is a little environmental impact comparison to be made.