• HOME
• WEBLOG
• ABOUT
• PROJECTS
• PHOTOS
• ARTICLES
• JUNK
• CONTACT

Wood Gasification - Cleaner Energy For The Developing World

A developing world energy crisis? How can that be when people in the developing don't even drive cars or use electricity very much? How can people who live their lives the same way now as they did in the 19^th century have an energy crisis?

Wood is King

Half of the world's people still use wood as their primary source of heat and light. In some places wood has become too scarce and they have started to use animal dung and other primitive fuels for energy. The proper management of forest resources in developing countries is often quite lacking, and we are losing them at an alarming rate. Where is all this wood going? Into toothpicks, pencils, houses? Half of all wood harvested is used as fuel, up in smoke. Deforestation is a result of a society's quest for food and energy.

The Problems with Burning Wood

Most wood fires in developing nations are in open pits or fireplaces. The heat is used very inefficiently, a lot of smoke is created, and a lot of wood is wasted.

The World Health Organization has classed indoor smoke pollution 4^th in the top health burdens in developing countries. Unlike the carbon dioxide emissions from the fossil fuels that we use in the developed world, wood fires are a local problem. Inefficient fireplaces and stoves burn wood and dung at low temperatures which promotes smoking. Smoke permeates people's lungs and decreaeses visibility, and wood smoke is no better than cigarette smoke in its effects on human health. Many of the people do not even know that the smoke is bad for their respiratory system and eyes, and it is simply considered to be a fact of life.

The wood fires and stoves are also highly inefficient when it comes to delivering energy. Most heat is simply wasted in the process of starting the fires, and up the sides of the cookware. Because of the labor involved with building fires, they are often kept burning continously even when the heat and light are not needed. Because of the inefficiency, more wood must be consumed to perform the same amount of work, and the people begintheir quest to find more wood or to use dung and other even dirtier fuels.

Common thought has it that the best way to get cleaner energy into these developing nations is to deliver forms of energy used in the developed world (or in other words, fossil fuels). Electricity and propane (LPG) are the most common. This practice would end the wood smoke problem but it is also very capital-intensive, and often the energy devlopment is done by Western corporations whose goal is not to be a chairity but to turn a profit.

It also makes little sense to install a "modern" energy system which is dependent upon finite and polluting fossil fuels. It would also be unsuitable to lock these nations into a centralized energy system which relies on expensive, inefficient, and large power plants and distribution equipment.

A Solution - Gasification

The phrase "now you're cookin' with gas!" is often used when someone does something well or efficiently. Chefs and cooks prefer gas burners over electric ones because of their ability to provide even and instant heat with a high level of control. When fuels are in a gaseous state, they can be used much more easily than if they are solids or liquids. Liquid and solid fuels must be converted to gases and vapors to burn - and that process is uncontrolled when the fuel is directly burnt.

The solution is to turn the solid fuel into a combustible gas, possibly clean the gas up, then mix it with air and burn it.

Gasification converts solid wood into clean-burning and convenient gas fuel. No toxic wastes are produced by the "tar-burning, char-making" downdraft gasifiers - only "wood gas", charcoal, and ash. Wood gas is quite safe due to the fact that it is made in small quantities and combusted almost directly after being created.

Wood gas consists mostly hydrogen and carbon monoxide, with nitrogen levels being high as well due to dilution from the air. As long as the gas is burnt, the carbon monoxide is safely oxidized to carbon dioxide.

Wood-Gas Cookstoves

Developing nations would not even have to employ wood gas production on an industrial scale if the only goal is a clean cookstove. Wood-Gas burning stoves can be built from widely available metal cans and they provide clean and efficient heat where it is needed.

Wood gas stoves first gasify the wood, creating a high heat output. This can be used for boiling or frying foods. After the wood has been gasified, charcoal remains which then burns. The charcoal releases a slow, even heat. This can be used for grilling or simmering foods. The design of the stove allows almost all of the heat to be put to use, meaning a much smaller fire can be used.

Some stove designs use forced air provided by a small battery-powered fan. Others use a chimney-like device to create a draft. The wood is placed into the stove and ignited from the top. The top layer of wood burns, creating charcoal. The heat from the charcoal layer burning heats the wood below it, and ignites it. The gases (carbon dioxide and water) flow through the charcoal layer. Glowing hot carbon has a unique ability to strip oxygen molecules off of anything that it touches, so it converts the water into hydrogen, and the carbon dioxide into carbon monoxide. These two gases are flammable and they are ignited once mixed with air above the charcoal layer. The result is a flame that is much more controlled, and cleaner than that of raw wood burning. Some commercially available wood gas stoves with forced air fans are capable of producing a blue flame with almost no soot and dirt.

After the wood has been gasified, charcoal remains. For a while, the charcoal itself is gasified but soon looses energy and just burns. The charcoal can be saved for later use if desired.

Last Modified: 05/25/2008
Created: 06/13/2005