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Wisconsin K-12 Energy Education Program

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Energy Resource Fact Sheets

Facts about Wood

Introduction

Wood was once the main energy resource used

during the early history of the United States, but now it

plays only a small role in meeting the nation’s energy

needs. Still, in certain parts of the country, including

(“chemical energy”- sugars), which is stored in the wood itself. Wood is a renewable resource, which means

that additional resources can be grown to replace any wood that is cut down.

Wood for heating is sold in units called cords. A cord is a stack of wood 8 feet long, 4 feet high, and 4 feet wide

(128 cubic feet). A face cord is a stack 8 feet long, 4 feet high, and 12 to 16 inches wide (32 to 40 cubic feet).

A cord of hardwood such as maple, oak, or hickory may contain twice as much energy as a cord of softwood

such as pine or balsam r. This variation in energy is because a cord of hardwood is more dense and heavy

than softwood (see Energy Content and Weight per Cord of Certain Types of Wood Found in Wisconsin).

Facts about Wood

Energy Content and Weight per Cord of Certain Types of Wood

12.5 5,787 2,160

11.3 5,381 2,100

Source: Solar Energy Project “Heating Value of Wood” p. 2–13 in “Wood: Stored Solar Energy.” Renewable Energy Activities for Biology.

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Wisconsin K-12 Energy Education Program

keepprogram.org

Energy Resource Fact Sheets

Facts about Wood

Facts about Wood

uses a wood stove with an efciency of 71.7 percent.

Wood Energy Potential

Forests cover one-third of the total land area of the United States (766 million acres). About two-thirds of this

forest is productive enough to grow commercially valuable trees. About 17 million acres, or 48 percent, of

Wisconsin’s land are forested. Since 2009, Wisconsin has seen a 2.1 percent increase in forested land. With

a general increase in forest age throughout the state, overall growing stock volume in Wisconsin’s timberland

has increased as well. According to a study conducted at the University of Wisconsin – Madison, Wisconsin’s

forests have the potential to displace almost 19 percent of statewide natural gas demand.

Harvesting, Processing, and Transportation

Methods for harvesting wood range from simply cutting down a tree with an ax or saw to removing all the

Wood Fuel Production

In 2015, 10 percent of energy supplied to the United States was from renewable sources, and biomass wood

accounted for 21 percent of those renewables. The forest products industry consumes almost two-thirds of

all fuel wood. Nearly 20 percent of U.S. homes get some heat from burning wood, while about four percent of

households across the country use wood as the main fuel for home heating.

Approximately 200,000 (9 percent) of Wisconsin homes burn about 1.2 million cords of wood every year. The

total amount of wood energy used by all economic sectors in Wisconsin in 2012 for heating was more than

46 trillion Btu, about

three percent of all

the energy used in

used for fuel. Sweden

and Finland are world

leaders in using wood

as an energy source.

In Sweden the majority

of wood used is for

fueling district heating

plants.

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Wisconsin K-12 Energy Education Program

keepprogram.org

Energy Resource Fact Sheets

Facts about Wood

Electricity Produced from Wood

Certain electric power plants in the United States and the rest of the world burn wood to generate electricity.

Like coal and fuel oil, wood is burned in a boiler that heats water into steam. The steam then spins a turbine

connected to an electric generator. Power plants usually burn wood along with other fuels; they rarely burn

wood exclusively.

Wood is a major fuel source for industries that produce wood products. Most wood-red power plants currently

operating in the United States are owned by industries such as the paper and pulp industry. Many of these

industries use wood energy to provide steam, heat, and electricity (this multiple use is called cogeneration).

In parts of the United States where wood is plentiful, many rural homeowners burn wood for space heating. About

200,000 (9 percent) of Wisconsin homes burn wood as a primary or secondary fuel source. Wisconsin residents

use about one-half of all wood fuel, while the other half is used for commercial and industrial purposes.

Wood is also used to make building materials, pulp, and paper. Other uses include consumer products (e.g.,

toys, sporting equipment, pencils, and musical instruments) and chemicals. Wood and its derivatives are used

in as many as 10,000 products. Generally, except in facilities that utilize cogeneration, wood harvested to make

wood products does not come from the same sources as wood harvested for energy.

carbon monoxide, and polycyclic aromatic hydrocarbons that may cause bronchitis, emphysema, and cancer.

Indoor air pollution may occur due to improper burning or leaks in pipes and chimneys. Outdoor air pollution

may arise when large numbers of residents burn wood. However, high-efciency wood stoves can reduce air

pollution problems. In the United States, new wood stoves are required to emit 70 percent fewer particulates

than those sold before 1990. Burning wood also releases carbon dioxide, a cause of global climate change.

By replanting trees after a timber harvest, the carbon dioxide emitted by burning wood can be absorbed and

the pollution can be offset.

Removing most or all of the trees from a large area (sometimes called deforestation or clear cutting)

can harm wildlife habitat and cause erosion. Deforestation may also lead to wood shortages and make

tree replanting difcult due to topsoil loss. If the deforested area had moderate-high diversity prior to

Facts about Wood

Facts about Wood

Wood will continue to play a role in providing energy for heating, Wood will continue to play a role in providing

energy for heating, cooking, and generating electricity in the United States and the world. However, wood will

not replace fossil fuels as an energy source due to efciency, limited availability, restrictions on harvesting

wood in protected areas, and competing uses for making various products. Although the use of wood as an

energy resource is expected to increase, it will likely be limited.

References

Food and Agriculture Organization of the United Nations. Forest Product Statistics: 2014 Global Forest

Products Facts and Figures. 2015. Retrieved from: fao.org/forestry/44134-01f63334f207ac6e086bfe48fe7

c7e986.pdf

Travis Industries House of Fire Cost of Heating Worksheet. Retrieved from: travisindustries.com/

CostOfHeating_WkSht.asp?P=2

U.S.D.A. Forest Service. Forest Resources of the United States, 2012. General Technical Report WO-91,

October 2014. Retrieved from: srs.fs.usda.gov/pubs/gtr/gtr_wo091.pdf

U.S.D.A. Forest Service. Forests of Wisconsin, 2014. Resource Update FS-43, April 2015. Retrieved from:

fs.fed.us/nrs/pubs/ru/ru_fs43.pdf

Wisconsin Ofce of Energy Innovation. 2013 Wisconsin Energy Statistics Book; Chapter 3: Renewable Energy.

2013. Retrieved from: psc.wi.gov/Pages/Programs/OEI/WisconsinEnergyStatistics.aspx

Wisconsin Statewide Wood Energy Team. Wood Energy 101 – An Introduction to the Use of Woody Biomass

in Wisconsin.