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BTUs of Natural Gas?

rich67rich67 Member Posts: 21
I read in another thread here oil has about 139000 BTU's /gal. LPG has about 91000 BTU's /gal. Is NG about the same as LPG?  It seems that I might not save that much money by converting other than eliminating annual cleaning.


  • Tim McElwainTim McElwain Member Posts: 4,434
    Natural gas is not typically measured in

    gallons but of the three fuels it has the lowest BTU. We usually talk about BTU per cubic foot which is typically 1050 BTU's per cubic foot.a cubic foot is about 7.5 gallons. A unit of heating measurement is called a therm which is 100,000 BTU's.

    The issue at this time is the price of fuels so the savings is immediately there with natural gas as it is the lowest cost of the three. It does burn cleaner and has many options available (so does propane) as to equipment that oil does not.  

    I assume you have oil now, how old is the boiler as another option is to put in a power gas conversion burner in the oil boiler and set the oil aside in case prices change in the future.
  • rich67rich67 Member Posts: 21
    Yes I know but

    I was trying to compare apples to apples.  What's the BTU difference between LPG and NG in cu ft?
  • Tim McElwainTim McElwain Member Posts: 4,434
    Here is some info that may answer your question

    Propane vs. Natural Gas

    Natural gas is made up of several gases including propane, butane, and ethane and mostly consists of methane. While propane is a part of natural gas in its raw state, it is a hydrocarbon separated from the other gases at gas processing facilities. The propane that is separated during this process is stored and sold to propane dealers for end use by consumers. The comparison of propane vs. natural gas is widely used in applications for [u][color=#0000ff]vehicles[/color][/u] and residential fuel supply. Also, while propane is stored as a liquid, natural gas can be stored as liquefied natural gas (LNG), compressed natural gas (CNG) and in its uncompressed form, which is just referred to as "natural gas".

    Propane vs. Natural Gas - Energy Content Comparison

    While propane is sold and delivered in gallons, it can easily be converted to cubic feet, which is how natural gas is measured for delivery. The cubic foot unit of measurement pertains to both natural gas and propane in their vapor forms. Provided that 1 cubic foot of propane contains 2,516 BTU and 1 cubic foot of natural gas contains 1,030 BTU, it is accurate to say that propane contains over twice the usable energy content per cubic foot (2.44 times more). Applying these numbers to compare the energy values in real-world examples, we'll use a 100,000 [u][color=#0000ff]BTU/hr[/color][/u] furnace to demonstrate the comparison.

    §                                 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 ÷ 2516 = 39.7) in one hour

    In examining the costs of natural gas vs. propane, the rates of local energy utilities and propane companies differ and will need to be taken into account for accurate comparison. But to obtain the cost comparison between the two fuels, one must compare the cost of the energy value which can be obtained through local propane companies and utility companies. While utility companies provide price per cubic foot, propane companies provide price per gallon. Natural gas availability will generally determine whether or not propane can be used because many municipalities will require the use of natural gas if a [u][color=#0000ff]business[/color][/u] or residence is within a certain distance of a natural gas main line.

    Propane vs. Natural Gas Cost Comparison

    The cost comparison between propane and natural gas is much easier due to the fact that unlike electricity, natural gas and propane can be directly compared based on their individual [u][color=#0000ff]BTU ratings[/color][/u]. Seeing that natural gas contains approximately 1,030 BTU per cubic foot and propane contains 2,490 BTU per cubic foot, we can easily derive each fuel's cost per BTU and compare their differences in price for more realistic volumes.

    Let's assume the cost for natural gas is $15.00 per 1,000 cubic feet. This means that $15.00 will purchase approximately 1.03 million BTU's of energy. This would be equivalent to 11.26 gallons of propane. At $2.50 per gallon of propane, natural gas would be a more cost effective energy solution. Breaking it down even further, natural gas needs to be more than $28.00 per 1,000 cubic feet for propane to be a more cost effective energy solution (provided the cost for propane is $2.50 per gallon.

  • ZmanZman Member Posts: 6,288
    edited September 2012
    Cost per million btu

    The easiest way to get where you are going is to use the attached spreadsheet and convert everything to price per million btu output. You put in you local market pricing and efficiency of the appliance and viola.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • rich67rich67 Member Posts: 21
    Thank you for the info

    So, hypothetically if I burn 2 gallons of fuel oil (278000 BTU) in a day to heat my house, that would be equal to 270 cu ft of natural gas or 111 cu ft propane?
  • ZmanZman Member Posts: 6,288
    You got it!

    That looks correct. It seams kind of strange to figure volumes of gas because it depends on an assumed pressure. Using therms for ng and gallons for lpg works better for Me.

    Be sure to figure in the efficiency of the appliances if you are doing an upgrade.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
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