| With energy prices continuing to reach an all time | | | | a normal path of evolution for these |
| high, more and more people are turning to | | | | manufactures if they want to continue to sell their |
| alternate fuel sources. One of those fuels is wood. | | | | products into the future. |
| Although people have burned wood for years, | | | | The bulk of manufactures are achieving this |
| why is there so much buzz about outdoor wood | | | | cleaner burning stove through the use of more |
| burning boilers (or furnaces as they are most | | | | modern technology. Although there are many |
| commonly referred to). | | | | different ways of doing this, the basic principle is |
| Well, first off, lets talk about what these are. If | | | | the same. That is you need to increase the |
| you live in a neighborhood where one has been | | | | "combustion temperature" inside the firebox. |
| installed, then I am sure you know what they are! | | | | In most cases this is achieved by adding a |
| In general they are a self-contained building that | | | | secondary combustion chamber. And in some |
| looks something like a shed. They consist of a | | | | cases introduces "secondary air". Regardless of |
| firebox and an area that contains water. | | | | the method used, the goal is to get the exhaust |
| Wood is added to the firebox and the heat that | | | | gases / gases of combustion, hot enough to |
| the wood produces is then passed to the water, | | | | gasify, or ignite. |
| which in turn enters the house or building and is | | | | By getting the gases to ignite in the secondary |
| used for heating and domestic hot water. | | | | combustion chamber several things are achieved. |
| Sounds like a great thing right? It is. Or is it? The | | | | First, the gases are being burned at a very high |
| biggest problem that most people have with | | | | temperature and therefore are achieving |
| outdoor wood furnaces is most produce a ton of | | | | "complete combustion" (as much as possible in this |
| smoke at start up. This smoke can also last for a | | | | type of situation) which in turn produces more |
| long time during operation (heat cycle) due to the | | | | heat. |
| large wood load stored in the firebox. | | | | The more heat that is produced, the more heat is |
| So why do they smoke so much? There are | | | | transferred to the water, thus making the stove |
| several reasons. The first reason is most | | | | more efficient. Because we are able to gasify and |
| manufacturers do not build these to be very | | | | burn the gases trapped in the smoke, the overall |
| efficient. As the fire burns, the firebox rarely gets | | | | smoke output is greatly reduced. |
| hot enough to "gasify" the wood gases driven out | | | | The idea of gasification is not new. In fact, the |
| of the burning wood. These gases consist of | | | | extraction of hydrogen gases from wood was |
| many compounds. The most common compounds | | | | used during World War Two by the military to run |
| are hydrogen gas, carbon monoxide and methane | | | | jeeps and alike. |
| gas. Because these compounds don't get hot | | | | One of the attractions towards burning wood is |
| enough to ignite and combust, they escape up the | | | | that it is a renewable source of energy. |
| chimney in the form of dense smoke. | | | | And, of course reduces our need for oil from |
| Another leading cause of dense smoke comes | | | | others countries. |
| from burning "green wood". Green wood is wet | | | | Despite what some well-intentioned folks may tell |
| wood. In other words it has not been "seasoned" | | | | you, burning wood is no more harmful then some |
| or left out to dry for a year or two. | | | | fossil fuels from a carbon dioxide standpoint. In |
| As the green wood burns it gives off water | | | | short, here's why. |
| vapor or steam from the water trapped inside | | | | Wood contains carbon dioxide as part of the |
| the wood. This leads to heavy smoking. This | | | | natural growing process. It's part of nature. |
| problem is a very simple one to fix. Don't burn | | | | Of course all fossil fuels contain this gas as well. |
| green wood! In fact, even know some makers of | | | | This is one of the big problems with burning fossil |
| outdoor furnaces and wood stoves say that you | | | | fuels. |
| can burn green wood, you shouldn't. You will | | | | So, why is burning wood different? Because trees |
| consume more wood if you burn green wood, | | | | contain carbon dioxide that will naturally escape |
| and thus loose even more efficiency. Some of | | | | from the wood in time anyway. That is to say, |
| the heat energy from the existing fire needs to | | | | as a tree dies and decays it will emit carbon |
| be used to drive the moisture out of the wood | | | | dioxide. |
| instead of being used to heat the water. | | | | Fossil fuels on the other hand, only emit carbon |
| A responsible owner of one of these devices, | | | | dioxide when burned. So the thought here by |
| such as myself, can vary the way you "fire the | | | | most, is if the fossil fuels were never burned and |
| furnace". Instead of filling the firebox to capacity | | | | left underground there would be no carbon dioxide |
| every time, just add less wood as well as the | | | | emission. |
| time of day. I fire my stove at night so the | | | | Remember, this is not to say that burning wood |
| smoke doesn't bother my neighbors during the | | | | is any cleaner, it's just that burning wood adds |
| day. And by adding less wood at each loading, it | | | | less NET carbon dioxide to the environment. (So |
| cuts down on the amount of smoke output. | | | | long as we continue to burn fossil fuels) |
| For the most part, most outdoor wood furnaces | | | | So with the help of the EPA and stove |
| are not regulated by the EPA. However, that is | | | | manufactures, we will soon have a wood burning |
| changing. Due to the overwhelming popularity of | | | | outdoor furnace that will smoke less. Hopefully this |
| these things, the EPA is now starting to address | | | | will reach some middle ground between those |
| this problem. Most manufactures of outdoor | | | | who are upset over smoke and those who STILL |
| furnaces are now building models that conform to | | | | have a right to burn wood. |
| smoke emission criteria. This is nothing more than | | | | |