Quiz: What You Don't Know About Wood Energy
Photograph from Juergen Henkelmann Photography/Alamy
You know that wood fires fueled civilization’s advance from its earliest days, but how much do you know about how wood is used for heating, cooking, and electricity today?
Quiz by Marianne Lavelle
In what year did coal surpass wood as the dominant energy source in the United States?
Fuel wood was the dominant source of energy from the founding of the American colonies until about 1885.
What percentage of the world’s population today relies on wood and other biomass for cooking and heating?
- 10 percent
- 20 percent
- 30 percent
- 40 percent
About 3 billion people, or more than 40 percent of the world’s people, rely on wood and other biomass—charcoal, agricultural waste, and dung—for fuel. The United Nations estimates emissions from inefficient wood cookstoves cause 1.6 million premature deaths each year.
In some parts of Africa, women and children—the primary fuel gatherers—must walk an average of 10 kilometers (6.2 miles) daily to collect fuel wood, because nearby sources have been depleted. What is the average weight of a load carried by fuel collectors in sub-Saharan Africa?
- 2 kilograms (4.4 pounds)
- 8 kilograms (17.6 pounds)
- 10 kilograms (22 pounds)
- 20 kilograms (44.1 pounds)
The average load carried by fuel collectors in sub-Saharan Africa is 20 kilograms (44.1 pounds), though loads as heavy as 38 kilograms (84 pounds) have been recorded, according to the International Energy Agency.
Which of the following industrialized countries derives the largest share of its energy from wood biomass?
Sweden derived 23 percent of its energy from wood biomass in 2011, making it one of the leading industrialized countries in the world in use of wood energy. The country has an extensive district heating system, with two-thirds of the fuel coming from biomass. How many of the 117.6 million U.S. households use wood as a primary heating source?
How many of the 117.6 million U.S. households use wood as a primary heating source?
- 1 million
- 2.5 million
- 25 million
The U.S. Energy Information Administration calculates that 2.5 million U.S. households used wood as their primary heating source in 2012, forecasting the number would grow 3 percent within a year, faster growth than for any other heating fuel.
What region of the United States uses the most wood for heating fuel?
- The Pacific Northwest
- The South
- New England
Twenty percent of New England homes (1.1 million households)—half of those in rural areas—use wood as either a primary or secondary fuel for space heating, water heating, or cooking, nearly twice the national rate. (See related story: High Fuel Costs Spark Increased Use of Wood for Home Heating
What type of wood has the most heating potential by weight?
- Oven-dried hardwood
- Fresh-cut hardwood
- Air-dried hardwood
- Wood pellets
One pound (0.45 kilogram) of oven-dried hardwood has an available heat value of about 8,600 BTU, while wood pellets are next at about 7,750 BTU, followed by air-dried hardwood. Fresh cut wood has far less heat potential because of its high moisture content.
How much heating oil would it take to equal the heat of one cord of air-dried hardwood? (One cord is a pile of wood four feet high, four feet wide and eight feet long)
- 1 gallon
- 10 gallons
- 100 gallons
- 1,000 gallons
In a wood-burning unit with an efficiency of about 50 percent, a cord of air-dried hardwood would provide the energy equivalent of about 100 gallons of heating oil. The U.S. Energy Information Administration estimates the average home that heats with wood uses two cords per winter.
True or false? A wood fire in a traditional open masonry fireplace can make a room colder.
Traditional fireplaces draw in heated air from the room for combustion, and send it up the chimney, making it an energy loser. High-efficiency fireplace inserts help increase the efficiency of older fireplaces.
Pellet stoves that burn compacted sawdust, wood chips and agricultural crop waste, can reach 85 percent combustion efficiency, far more efficient than fireplaces and most wood stoves. What is important to have on hand for the pellet stove to work?
- A chimney
- A computer control
Pellet stoves require a small amount of electricity to run fans, controls, and the pellet feeder. But the pellet stoves have low emissions, and exhaust gases are vented by way of a small flue pipe that can be directed out a sidewall or upward through the roof.
The largest wood biomass power plant in the United States, which came online in 2012 in Nacogdoches County, east Texas, is designed to be fueled by one million tons of wood waste annually, and to provide power to how many homes?
Southern Company’s Nacogdoches Generating Facility is designed to provide electricity to 60,000 homes, with electricity fueled by sawmill and forest waste wood gathered within a 75-mile radius of the plant.
Which one of these renewable sources contributed the most energy to the United States in 2012?
- Wood and wood-derived products
Wood and wood-derived products provided more energy than any other renewable fuel source except for hydroelectricity. That’s due mainly to the industrial use of fuel processed from wood waste to generate power that runs pulp- and paper-industry plants.
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