Forestry

Fuelwood

Objectives

• Today you will learn:

History

• More than half of all wood produced today, worldwide, is used for fuel.

• In developed countries wood fuel has been replaced by gas, oil, coal, and electricity.

History

• 1860- The per capita use of wood for fuel in the U.S. had reached an average of about 4 ½ cords.

• Next to lumber, fuelwood was the most important use of wood.

• 1880- fuelwood reached its peak volume of consumption.

• Why? – The industrial expansion, primarily with settlement

of the west.

History

• 1920- fuelwood consumption gradually declined as it was being replaced with gas, oil, coal, and electricity.

• Wood was still used in rural areas where these fuels were largely unavailable.

• 1920-1970- fuelwood declined drastically, and almost disappeared as the primary source of heat in homes.

• It still remained as a source of entertainment.

History

• By the early 1970’s the masonry chimney was no longer compatible with the energy consumption of air conditioners and central heating using electricity or gas.

History

• 1973- the price of oil was $2.15 a barrel and fuel oil was about $0.15 a gallon.

• The 1973 oil embargo caused fuel prices to rise.

• 1979- oil was $39 a barrel, causing the price of electricity and coal to also increase drastically.

• The invention of the airtight wood stove made wood a viable option again.

Advantages

• It burns relatively cleanly in properly designed heating appliances with little residue in the form of ash.

• It contains no sulfur and does not pollute from this source.

• It is also cheaper than most fuels and can often be obtained for free.

Disadvantages

• It must be dried before it can be burned satisfactorily.

• It is heavy and requires a large storage space. • It deteriorates over time• Produces odor that can be detected for long

distances.• Odors penetrate clothing and lingers for

extended periods of time.

Disadvantages

• It is dirty to handle.• Insects and termites may be present. • Produces smoke with large amount of

particulate and hydrocarbons present unless burned at high temp.

• Tars and creosote are produced leading to chimney fires.

Disadvantages

• Creosote is formed from the use of small fires that are not hot enough to keep the chimney clean and used on warm days or in stoves that are too large for the area to be heated.

• A chimney fire resembles a small volcano at the top of the chimney and sounds like a locomotive at the stove or fireplace.

• Fires usually occur on the coldest when the chimney is most needed since large fires are usually built.

Industrial Uses

• Wood fuel is quite satisfactory because it can be burned at a high enough temperature to eliminate the creosote formation.

Combustions

• The fire triangles.– Heat/Spark– Fuel– Oxygen

• Removal of these components will cause the fire to go out.

• Control of any fire depends on the elimination of one or more of these components.

Combustion

• Gas and Oil– Regulate supply of fuel.

• Solid Fuel– Coal• Oxygen supply under the fire

– Wood• Oxygen supply over the fire.

Heat

BTU- The British Thermal Unit is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit in one hour. • 1lb of dry wood:

– 8600 BTU’s• 1lb of green wood:– 4300 BTU’s

• 1lb of oil:– 17,500 BTU’s

(140,000 BTU’s/Gal)

• 1gal of propane:– 91,000 BTU’s

• 1gal of gasoline: – 120,00 BTU’s

• 1lb of coal:– 12,000 BTU’s

Firewood

• Firewood is generally sold by the cord or by weight. • A standard cord is 4 feet by 4 feet by 8 feet and contains

128 cubic feet of wood, bark and air space. • A cord contains about 79-90 cubic feet of actual wood. • A cord of firewood

– 7,500 lbs

• A cord of pulpwood– 5,000 lbs(A pickup truck can only hold between 1/3 and ½ cord of wood.)

Firewood

• Specific Gravity– The ratio of weight of water to the weight of

another substance.

• Density– The weight over voulme

• The amount of heat in wood depends on its moisture content and specific gravity or density.

Firewood

• All wood has a similar S.G.– 1.53

• Denser woods are more desirable for fuel because they contain more wood and less air per unit volume.

• Best Firewoods– Oak – Hickory– Hard Maple

Artificial Logs

• Made from wax mixed with saw dust or shavings from various woods.

• Such logs are generally safe to burn in open fireplaces but are dangerous to burn in closed or air-tight stoves.

• Have a higher heat content because of wax binders.– 17,000 BTU’s per hour

Concerns• Burning wood at high temperatures with excess air

produces nearly complete combustion with carbon dioxide, water, and wood ashes as the end products.

• Incomplete combustion produces carbon monoxide, carbon (soot), Charcoal, and large amounts of unburned particles in the form of dense smoke.

• Pollutants:– Carbon Monoxide, Oxides from nitrogen, sulfur,

particulates, and hydrocarbons.

Safety

• Accidents using the chainsaw and axes are common for inexperienced persons cutting wood for fuel.

• Over 100 persons per year are killed and many thousands maimed by chainsaws and felling trees.

• Most injuries are to the head and face and the leg and knee.

Some have been cut in half and survived.

Safety

• Kickback– Because the high torque produced by the fast

moving chain rounds the tip of the bar, the saw is thrown upward or down when a obstruction is encountered.

• Many new saws have redesigned bar tips to reduce this problem.

Safety

• Equipment recommended by OSHA:– Hard Toe Shoes– Hard Hat– Gloves– Hearing Protection– Goggles

• Never cut near a powerline. If a tree should fall on a power line. DO NOT ATTEMPT TO CUT IT FREE as you may be killed or severely burned.

Felling a tree1. Inspection of the site.2. Clear an escape path of all brush to one side behind the tree.3. Wedge Cut

- 1/3 way through tree- Used to create a hinge for falling tree.

4. Felling Cut

- On opposite side of wedge cut above apex.

5. Limbing

- Keep tree between yourself and the saw.

6. Bucking- Cutting to usable lengths.

Safety

• A medical condition known as white finger or Raynaud’s disease is common with persons using chainsaws.

• Many European countries restrict the hours per day or week a chainsaw can be used.

Review