Firewood

Firewood is any wooden material used as a fuel source for combustion. Unlike industrial fuels like wood pellets, firewood usually takes the form of recognizable logs or branches.

This resource is renewable because trees can regrow. However, demand can outpace the rate at which forests regenerate. To maintain a steady supply, people must use good forestry practices. Efficient burning devices can also help make the most of available wood.

The quality of firewood depends heavily on its moisture content. Wood is categorized as either seasoned or unseasoned. Seasoned wood is dry and typically has a moisture content of 20% or less. Unseasoned wood, often called "green" wood, contains much more water. In fact, green wood can weigh 70 to 100 percent more than seasoned wood. When you burn green wood, the fire must first use its energy to evaporate the water. This process boils the moisture away before the wood can actually burn. Consequently, dry wood delivers much more heating energy than wet wood.

Preparing firewood involves several specific steps to ensure it burns efficiently. Most people harvest wood and then move it closer to where it will be used. A common step is splitting the wood into smaller pieces. Splitting increases the surface area, which allows for faster seasoning. People split wood manually using a splitting maul or a wedge and sledgehammer.

Some use hydraulic machines or kinetic log splitters. A kinetic splitter uses a motor and a large flywheel to store energy. There are even tapered screw-style designs that auger into the wood to split it.

Proper storage is essential to keep wood dry and prevent rot. The primary goal is to keep water away while allowing air to circulate. Simple stacks involve placing logs next to and on top of each other. To prevent rot, it is helpful to use pallets to raise the wood off the ground. When stacking outdoors, people often place the bark facing upwards. This allows water to drain off the logs.

Some cultures use a specialized circular method called a Holz hausen. This "wood house" is a large stack about 10 feet wide and 10 feet high. It can hold about 6 cords of wood. The design uses a central chimney of upright pieces to encourage airflow. This method helps the wood dry quickly within a small footprint.

For most of human history, firewood was the primary fuel for warmth and cooking. This changed during the Industrial Revolution when the use of coal spread. In medieval times, the right to gather wood, known as wood botes, was a valuable part of many leases. Even in 19th-century America, the writer Henry David Thoreau noted that everyone, from peasants to scholars, required wood.

In Nigeria, firewood remains vital for many uses today. It is used for cooking, heating, and making charcoal. It also plays a role in various cultural and religious practices.

Measuring firewood can be complex because it is often sold by volume. In the United States and Canada, a common unit is the cord. A full cord has a volume of 128 cubic feet. This measurement includes the wood, the bark, and the air spaces in the stack. There is also a smaller measure called a face cord, which is one-third the volume of a full cord. In the metric system, wood is often sold by the stère, which is 1 cubic meter. Because stacks contain air, the actual volume of solid wood is often less than the measured volume.

While firewood is useful, it has environmental and health impacts. Burning wood can cause respiratory issues and other diseases due to smoke. Collecting wood can also lead to deforestation if not managed well. Additionally, transporting wood over long distances can accidentally spread invasive insects and diseases. In North America, harvesting standing dead timber can help reduce the intensity of bushfires. However, this also removes habitats for animals like owls, bats, and rodents that nest in dead trees.