My main focus is wood gasification, but almost all of what I am including may be used for all biomass gasification. I know that many people want to know what the process of wood or biomass pyrolysis is as well. I will cover this as well as the other three processes in gasifiers. I also want you guys to understand that this process can help us with our energy independence.
Gasification is used to convert any carbon-based materials into Combustible Gasses (CO-carbon monoxide and H2-Hydrogen) by using a chemical reaction between the solid carbon fuel and a controlled amount of oxygen at high temperatures.
This is the ultimate Sunshine to energy process. We start with Sun and Carbon Dioxide which is where our Trees and Other biomass will come from. Then that is used as fuel to create heat and gas fuel, which can also be used for heat and combustion.
Wood is fully renewable, so the sustainability is much higher than commercially available products. You can easily build a gasifier, but it takes lots of petroleum products to make solar cells. So… even those panels aren’t true sustainable energy.
Some different fuels for gasification include wood in the form of sticks, chips, and pellets and dried crops.
Drying is simply using the heat imparted on wet biomass to create dry biomass and water. We have to burn some fuel before we can have this heat.
Pyrolysis is in the space with no air. If you use heat from combustion to process dry biomass with no air, it will make charcoal and tar gas. We have to get above 270 C for this to happen.
Combustion: That tar gas and charcoal, with oxygen from air, will combust creating water (H2O) and Carbon Dioxide (CO2). During normal combustion, you get heat, water, and carbon dioxide. Example: C3H8 + 5O2 –> Heat + H20 +3CO2. This is also called an exothermic reaction. Heat released by this reach up to 1400 C.
If we limit the Oxygen, we still get combustion, but we get this — Heat + H2O + CO2 + CO + H2. Both CO and H2 are combustible.
Reduction: This requires a lot of heat. The red hot charcoal left over, CO2 and H2O then makes H2 and CO, which are both the main gasses created. Carbon (Char) reacts with CO2 and makes CO. The water vapor byproducts are used. Carbon (Char) reacts with CO2 and makes CO. CO2 + C + Heat –> 2CO. It also reacts with the water, takes oxygen and makes CO and H2. H2O + C +HEAT –> H2 + CO. This is an endothermic reaction (needs heat added to it).
This stage makes methane as well when the char carbon binds with some of the Hydrogen and some CO also reacts with H with a byproduct of water.
Now for the homework section of this post. Let’s create a Woodgas Camp Stove. Let’s start easy. My recent trial and error with an alcohol burner (which I will revisit) has made me think… It is much more viable to have a WOOD BURNING camp stove in your bag. Visit this document from Morrisville State College for a PDF.
Enter the challenge for: