Heat Value of Wheat, Corn and Rye for Grain Burning Stoves
But access to accurate information on the heat values of wheat, rye, and corn is not
easy to come by.
Most grain stove websites parrot the figure of 500,000 Btu's per bushel of grain when
in fact it's actually 15% to 20% less depending on the grain.
A better source for agricultural information is your local university cooperative
extension. The following bushel weight and heat value measurements for rye, wheat,
and corn are from Penn State's College of Agricultural Sciences.
Rye 56 lbs/bu 7,212 Btu/lb 413,881 Btu/bu (British thermal units per bushel)
Wheat 60 lbs/bu 7,160 Btu/lb 429,600 Btu/bu
Corn 56 lbs/bu 6,970 Btu/lb 390,320 Btu/bu
A quick glance shows the heat value for each grain is quite a bit lower than the
500,000 Btu per bushel frequently cited as the norm.
Using wheat as an example, let's compare the cost to heat a home using the 500,000
Btu rating versus the more accurate 429,600 Btu heat value.
According to Al Heath, an energy consultant in Maine, the "average" home in Maine
consumes around 150 million Btu's during the heating season.
This works out to 300 bushels of wheat per season at 500,000 Btu's vs. 349 bushels
at 429,600 Btu's - or a whopping 49 bushels difference!
At $5.22 a bushel you would have underestimated your heating budget by 16%, or
$256, by using the higher 500,000 Btu/bu figure.
Overestimating the heat value of any fuel will result in underestimating the amount of
fuel needed for the heating season and the corresponding cost. Winter temperatures
are unpredictable as it is without having to face a potential fuel shortage that could
otherwise have been avoided.
If you're interested in tracking the daily cash price for wheat and corn, check out the
Chicago Mercantile Exchange home page.
Rye is another story. Rye is such a thinly traded commodity it's difficult to get a timely
fix on the price. However, I did locate a Canadian rye farmer with a substantial supply
selling for $9 - $10 a bushel depending on the quantity.
If you're considering a grain boiler to augment or replace your current oil system,
here's an easy way to estimate how many bushels of grain you'll need.
Let's say you burned 1,000 gallons of fuel oil last heating season. Each gallon of
heating oil produces 139,000 Btu's, so multiply 1,000 x 139,000 to arrive at the
number of Btu's required per heating season. In this case the answer is 139,000,000.
Now divide 139,000,000 by the number of Btu's per bushel of grain. If you're going to
burn wheat, divide 139,000,000 by 429,600 for a total of 324 bushels. In other words,
it takes 324 bushels of wheat to equal the heat value of 1,000 gallons of fuel oil.
By the way, you can find the Btu value per unit for various fuels in the second column
of the Fuel Comparison Chart.
Grain burning stoves, or multi fuel
stoves as they're sometimes called,
have been available for decades. But
recent fuel price volatility has
renewed interest among
homeowners looking for ways to
control heating costs.
The three types of grain commonly
used as fuel in grain stoves are corn,
wheat, and rye. Of the three, corn is
by far the most widely consumed
because it is also the most widely