pladner wrote:I have natural gas available 2 miles from my home. It will cost between 15-$20,000 to run the line to my new home. I am trying to compare the savings of natural gas for 20 years to see if it is cost effective to spend the funds to run the line instead of using propane. I have the cost per gallon of propane and the cost per cubic foot of natural in my area. How do I convert one to the other to compare apples to apples?
You need to compare based on energy content. You can use either BTU or therms (100,000 BTU)
100 cubic feet (1 CCF) of natural gas is very nearly 1 therm (0.95 - 1.05, typically, depending on gas analysis). 1 gallon of LPG is about 0.91 therm. (91000 BTU).
Take the gallons of LPG you use (and the total price). Multiply gallons by 0.91 to get therms. Assume you need that many CCF of natural gas and price it out. Note that natural gas is usually price NOT per cubic foot, but per hundred cubic feet (CCF) or thousand cubic feet MCF. Here, we are paying about $1.12/CCF, and that has a little more energy than a gallon of LPG, a little less than a gallon of gasoline.