Build It Solar -- free plans for hundreds of solar projects

The Renewable Energy site for Do-It-Yourselfers                

Build It Solar -- plans to build solar energy projects


Fuel Comparison Calculator

This calculator provides a quick way to compare the cost and CO2 emissions for various fuels.


The calculator estimates the cost and CO2 emissions for each fuel to deliver 100,000 BTU's of heat to your house. 

The calculator takes into account the cost of the fuel, energy content of the fuel, and the efficiency of your furnace.



For all the fuels you are interested in:

Fill in the "Fuel Cost per unit" -- this is what you pay in dollars for the fuel unit listed.  For example, if you pay $2.10 per gallon for propane, then type 2.10 into the Fuel Cost column for Propane.  Make sure you fill in the price for the unit size listed -- for example, corn is $'s per ton, not $'s per bushel.


Fill in the "Efficiency" column for the furnace or heat plant you will use.   For example if you have a 95% efficient condensing NG boiler, you would fill in 95 in the "Efficiency" column for Natural Gas.

Help with furnace efficiencies ...

For help in estimating Heat Pump efficiency ...


After filling in the data for the fuels you are interested in, click on the "Calculate" button.

The cost to produce 100,000 BTU of heat will be listed for each fuel in the "Cost" column.

This provides an "apples to apples" comparison of fuel costs, since all fuels are delivering the same amount of energy.


The CO2 emissions resulting from generating the 100K BTU will be listed in the "CO2 Emissions" column.


A full example is provide here ...

Fuel Type Fuel Cost per unit Efficiency
($'s per100K BTU)
CO2 emissions
(lbs per 100K BTU)
Natural Gas $/therm(ccf)
Propane $/gallon
Fuel Oil $/gallon
Electricity Resistance $/KWH
Electricity - Heat Pump $/KWH
Wood - Softwood $/cord
Wood - Hardwood $/cord
Wood - Pellets $/ton
Coal $/ton
Corn $/ton




Energy Information Administration  -- Information and forecasts on common fuel prices.


Build-It-Solar Fuels page -- Several sources of fuel information



- The default prices I've provided are just estimates based on a little bit of searching and my own energy bills.  You need to substitute prices for your area.


- Note that for wood, the unit is a full cord of wood -- 4 ft X 4 ft X 8 ft = 128 cubic ft of wood.  Wood is solid in a confusing array of sizes, so be sure to get prices for a full cord.


- Furnace efficiencies are mostly from the EERE site.  They do not include losses in heating ducts which can be considerable (so go seal and insulate your ducts!)


- CO2 emissions numbers are strictly the emissions associated with burning the fuel, and do not include energy involved in extracting, harvesting, growing the fuel, or transmission line losses.

Wood is a net zero because the carbon removed from the atmosphere in the growing tree is the same carbon released during burning.  The CO2 generated from running the chain saw and pickup gas to haul the wood are not included.


Corn is a net zero for the same reason as wood, but the CO2 emissions associated with growing the crop are not included, and may be considerable.


Fossil fuels (NG, propane, coal, and oil) do not include the CO2 emissions associated with extracting and transporting the fuel.


Electricity does not include transmission line losses.

- In estimating CO2 emissions from electrically fueled heaters, I have used 1.4 lbs of CO2 emissions per KWH of electricity.  This is the overall average for the US grid, and includes a mix of coal, gas, oil, nuclear, hydro, and others.  The actual value by state varies from 2.2 lb/KWH in states with all coal generation down to near nothing in VT which is nearly all hydro and nuclear.    Check the eGRID site to see where your state fits in...



- For help in estimating Heat Pump efficiency ...


- Heating values for the fuels used in the calculator are:

Natural Gas             100,000 BTU per therm or CCF  (note that some sources list a CCF at a lower value)

Propane gas            92,000 BTU per gallon

Fuel Oil                     142,000 BTU per gallon

Electricity                  3412 BTU/KWH

Soft Woods              15 million BTU/full cord

Hard Woods             34 million BTU/full cord

Wood Pellets           16.5 million BTU/ton

Coal          `               25 million BTU/ton (anthracite)

Corn                          16 million BTU/ton

These are primarily from the EERE site.


- The coal numbers are for anthracite coal.

- Efficiencies of of all of these burners and furnaces vary greatly -- especially the wood burners. Wood burners can be as low as 5% for open wood fireplaces up to 80% for the latest EPA certified wood burners.

For propane and NG furnaces, I've used an up to date non-condensing furnace (85%). New models of condensing furnaces can be up in the 90% to 97% area.

For wood stoves, I've used the efficiency number for "Newer EPA non-catalytic stoves" of 60%. Older. Older, non EPA certified stoves could be as low as 35%, while new EPA certified catalytic stoves could be up to 72%.

Some references on efficiencies:

The fuel comparison calculator...

Heated Up! -- a recent review of wood burner efficiencies...




blog comments powered by Disqus




// +---------------------------------------------------------+
// |                                                         |
// | Solar Analysis Tools - Fuel Comparison Calculator       |
// |                                                         |
// +---------------------------------------------------------+
// Copyright (C) 2008 Gary Reysa (
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 of the License, or (at your option)
// any later version.
// This program is distributed in the hope that it will be useful and encourage
// further development of solar tools, but WITHOUT ANY WARRANTY; without even
// See the GNU General Public License for more details.



Gary April 26, 2008

May 2, 2008 changed CO2 emissions for electricity to US grid average

November 2009 -- some corrections on coal  from Richard
June 2014 -- Changed efficiency for pellet stoves and added information of wood burning efficiencies.


Contact/About          Legal Disclaimer                Copyright 2005 by Gary Reysa