What Wood Should I Have In My Firewood Rack?

People often fill their firewood rack with any old type of firewood without ever taking in consideration that not all firewood is the same.  Sometimes people just call and order the firewood, have it delivered and stacked in their firewood rack without ever asking the seller what type of wood they will be getting.  This is a big mistake.

There are several factors that need to be taken in considered when determining the best firewood to get.  If you are burning wood as an alternative heat source, one of the things you need to know is how much energy the species of wood produces when burned.  If you are just going to burn the wood in a fireplace and are more concerned with the atmosphere and mood the burning wood creates, you will want a wood that produces a nice flame instead of just smoldering.  Another consideration you need to be concerned with the amount of creosote, if any, a particular type of wood produces when burned.

These are just some of the things you need to consider when buying wood to use as firewood.  There are several more, however for this article I am going to just cover one consideration.  I am going to discuss firewood based on the amount of energy it produces when burned.

In order to discuss how much heat a particular wood produces when burned we need to know what a BTU is.  BTU is short for British Thermal Unit.  This is how the basic measurement of thermal energy is quoted.  One BTU is the amount of energy needed to increase the temperature of one pound of water one degree Fahrenheit, measured at its heaviest point. This means, if you placed one pound of water with a temperature of 59°F into a pan and on burning wood, it would take one BTU to raise the temperature of the water to 60°F.

Now that we know what a BTU is lets look at how many BTU's different types of wood produce when burned.  The following chart shows how many million BTU's a cord of particular types of wood produces when burned.

(Info taken from California's Consume Energy Website www.consumerenergycenter.org)

As you can see, Live Oak is the clear winner producing between 34.4 and 36.6 million BTUs per cord of wood when burned.  This means if you were purchasing firewood as a heat source, you would get more bang for your buck if you purchased a cord of Live Oak verses a cord of say Black Willow which produces only 17.5-18.6 million BTU's per cord.  The wood that came in second surprised me. Eucalyptus produces between 32.5 and 34.5 million BTU's per cord when burned.  I have never burned Eucalyptus, but just looking at the tree I've always thought it would be a soft spongy wood and not produce much heat if burned.  I guess looks can be deceiving.

Anyway, as you can clearly tell you need to be selective in the type wood you let someone put in your firewood racks .  Armed with this information you can be a smarter firewood consumer.  Look for future articles where I will discuss other considerations for purchasing firewood I did not discuss here.