See Wood Heating values for other varieties. E.g. there are 9 varieties of red oak with different heat values.
* BTU's are Millions/Cord. The values for a species vary by source. Examples:

Type	U. Nebraska	Olson	Fogazzo	Sepulveda	EcoFire	Enrgy Engr
Almond		22.3-23.7	23.5	32.9	24
Oak	24-29.1	34.4-36.6	36.5	23-32	21-24	red 26-29
White Oak	29.1			28.2	23	28-31
Walnut	22.2	24.5-26.0	26.0	22.5-23.5	20	24

Pound for pound, all woods create the about the same amount of BTUs. Does this mean that a cord of seasoned pine puts out the same amount of heat as a cord of seasoned hickory? No! The hickory will produce twice the amount of BTU's of the pine because it weights roughly twice as much as the pine.
Softwoods usually have a lot of resin content that has high energy content so their total energy content per pound is usually higher than for hardwoods (often by about 5%), however the fact that they have lower density (less pounds per cord) and burn up faster makes them less attractive.
See Efficiency below

Volume of a pile of split wood:
A cord of wood is 4x4x8 or 128 cu ft, but there is a lot of air. 85 (67-100) cu ft of split wood per cord

Density of common woods range from 28 lb/ft³ for cedar to 64 lb/ft³ for post oak.

Some Common woods
Type   Green    Seasoned
Almond 52 lb/ft3
Maple  45-54      33-40
Oak    61-64      42
Fir    38         30-33
Pine   36-52      24-35

Building a better fire:

Before lighting a fire, make sure the thermostat is turned down so air heated by the central furnace will not go up the chimney. The easiest and best fire for either a stove or fireplace is achieved with a mixture of softwoods for easy igniting with hardwoods for longer burning and good coaling qualities. A cardinal rule of fireplace management is to keep a thick bed for glowing coals that drop through. The coals yield a steady heat and aid in igniting fresh fuel as it is added. Keep the fire burning by adding small amounts of firewood at regular intervals. A small, hot fire is much better than a large, roaring blaze because it burns more completely and produces less creosote.

To achieve a long-lasting fire that will heat the house overnight or while you are away, rake the coals toward the air inlet and use larger pieces of wood placed compactly in the firebox. Placing the pieces close together prevents the heat and flames from penetrating the load and saves the buried pieces for later in the burn cycle. Fully open the air inlets for 5 to 20 minutes, depending on the size of the load and the moisture content of the fuel. When the outer pieces have a thick layer of charcoal, reduce the airflow in stages to the desired level.

With some of the new highly efficient combustion stoves, you may have to alter this procedure slightly.

Links:

BTU Ratings:
   Heating with wood - characteristics at U. Nebraska
   Firewood Ratings and Info at Rutland Products
   About Firewood at sepulveda.com
   Firewood at Fogazzo wood fired ovens.
   Olson
   About Bruning Wood  at EcoFire.com


Firewood Facts and Fuelwood Characteristics at Oregon Dept. of Agriculture 
About Bruning Wood and Pollution at EcoFire.com
Firewood for Home Heating
Wood Fuel for Heating
Heating your Home with Wood at UC Davis
 Home Heating with Wood at CDC's National Ag Safety Database (NASD)
Heating with Wood Needs Care and Consideration
California Combustables (Firewood FAQs)
What kind of wood generates the most heat when burned?
FAQs of the Internet BBQ list
USDA Forest Service Forest Products Laboratory:
   Energy from Wood
   Tech Sheets for Hardwood and Softwoods
   Lodgepole Pine
   

• "Energy engineering fundamentals with residential and commercial applications" by Charles B Schuder
  
• "Wood Handbook: Wood as an Engineering Material, (1974)", Forest Products Laboratory, USDA, FS Ag. Handbook No. 72..
• Burning Wood and Coal by Susan Mackay, L. Dale Baker, John W. Bartok, Jr., and James P. Lassoie. 1985. Northeast Regional Agricultural Engineering Service, Riley Robb Hall, Cornell University, Ithaca, NY 14853. (607) 256-7654. 90 pp. $4.95.
• The Wood Burner's Encyclopedia by Jay Shelton and Andrew B. Shapiro. 1976. Vermont Crossroads Press, Box 333, Waitsfield, VT 05673. 155 pp. $6.95.
• Wood Heat Safety by Jay Shelton. 1979. Garden Way Publishing Co., Charlotte, VT 05445. 165 pp. $8.95.
• Heat Producing Appliance Clearances. NFPA No. 89M, National Fire Protection Association, 470 Atlantic Avenue, Boston, MA 02210.
• Chimneys, Fireplaces, and Vents. NFPA No. 211, National Fire Protection Association, 470 Atlantic Avenue, Boston, MA 02210.
• Heating With Wood. Larry Gay. Garden Way Publishing, Dept. 90731, Charlotte, VT 05445, 128 pp.
• Planning and Building Your Fireplace. Margaret and Wilbur F. Eastman, Jr. Garden Way Publishing, Dept. 90731, Charlotte, VT 05445, 128 pp.
• Woodstove Cookery. Jane Cooper. Garden Way Publishing, Dept. 90731, Charlotte, VT 05445, 204 pp.
• Woodstove Directory. 1986. Communications Press, P. O. Box 4474, Manchester, NH 03108.
• When Does It Pay To Burn Wood." 1980. Paul Stegmier and L. T. Hendricks. Wood Burning Quarterly - Home Energy Digest. V.4(2):4953.

Energy Efficiency values:

Ew	Wood Heater
0.10	Fireplace
0.25	Improved Fireplace
Nonairtight (Franklin) Stove
0.50-.65	Airtight Stove
0.60	Wood Furnace
0.65	Airtight Stove with Catalytic Combustor

Source: Home Heating with Wood at CDC's National Ag Safety Database (NASD), Oregon Dept. of Agriculture and Virginia Tech
Stoves at U. Idaho
See Home Heating Costs for comparisons with Gas, Oil and Electric.

Wood burning stoves and fireplaces
Advanced-combustion high-efficiency wood-burning appliances burn up to a third less wood while generating the same amount of heat, which means savings in labour and costs.

Smoke is the source of creosote, and older uncertified stoves and fireplaces release 40 to 80 grams of smoke per hour; new EPA-certified stoves produce only 2 to 5 grams of smoke per hour.

See: Wood Burning Stoves at U. Idaho

Seasoning
Seasoned wood means the same wood will cost you about $30 a cord more. Do pay attention to the dealer before he drops the wood. Check the measure and check the age. Seasoned wood, if it honestly is, will have cracking on the ends of the logs. It may also be darkened and weathered. Smack two pieces together, a 'thud' sound indicates the wood is green, a 'thunk' indicates dry wood.

Moisture content varies by type:

Type	Moisture
RedCedar, Eastern	12%
Douglas-Fir	12%
Elm, American	55%
Oak, White	33%
Pine, Eastern White	24%
Pine, Ponderosa	54%
Sycamore	81%
Walnut, Black	44%

See Firewood Ratings at C Johnson's Public Service Pages.

Seasoning:

Seasoning wood means storing the wood to dry. When wood is freshly cut, it is holding approximately 60% of its water content and wont be usable for a fire until the moisture inside drops to about 20% or lower. Youll need to let the wood dry for 6 months to 1 year for it to be seasoned. Some species may take longer, and your climate plays a role too.

Trees harvested in the fall, winter or spring will contain more water than those cut in the summer.

It takes at least six months of drying (providing wood is cut to length and stored to permit good air circulation) to bring the moisture content down to 30 percent, and a full year to get it to the desired 20 percent moisture. Source U. N. Hampshire

Ovendried wood will have about 12% moisture.

The Heating Value (HV) (Btu/lb.) can be calculated as:

HV =	8600
	1 + % moisture/100

Wood cut to length dries more rapidly. The moisture is most effectively removed through the cut cells at the ends of each piece. Wood greater than eight inches in diameter and four feet in length dries very slowly.

If you live in the northern climes, a good time to split the wood is when the it is frozen in winter. It gives a cleaner cut and takes less force to do the same work.

Hazards
There are many trees and shrubs in this world that contain toxins to humans--toxins that can survive the burning process. So, be careful what you use for BBQ or smoking meats.

In general, working with pine wood may cause dermatitis, allergic bronchial asthma or rhinitis in some individuals. See Lodgepole Pine at US Forest Svc.

Prices for smoking hardwoods will vary with your location. Prices are as of early 1998 include delivery and splitting. Where there is lots of hardwood, like in parts of the south, hickory can cost you as little as $75 a cord. In Carlsbad NM, you can buy a cord of pecan for $110. In the hill country of Texas, you can get a cord of oak for $80. In Southern California, where hardwoods are scarce, a cord of oak or mesquite costs $400, a cord of almond about $280. In Virginia, a mixed cord of hickory and oak runs $135. In central Illinois, a cord of mostly oak with some hickory and maple mixed in runs $90-100. In western Connecticut, a cord of oak with a little hickory and maple thrown in will cost you about $90. In Southern Oregon, a cord of oak runs $120, pear wood about $150.

Pine and/or Fir:
You can find good and bad for both:

DownToEarthHomesteaders
Pine is good firewood if you are going to use if for kindling. It makes a great fire-starter, but because of its high sap and resin content, you should consider whether you want to use it exclusively as an indoor firewood. Its a messy wood to work with, but smells great!

Pine burns very quickly therefore hotter but less overall btu's

Don't burn pine: Best Logs for a Wood Burning Stove | Choosing Firewood

Pine is OK: "Never burn pine in the woodstove!" is a myth | Hearth.com Forums Home

Fir is best: The Best Firewood for Your Wood Stove or Fireplace

Firewood: What Type Should You Use? | Bob Vila
Pine
Widely available and highly sustainable in northern climates, pine seasons faster than hardwood varieties, is easy to split, and easy to start. The cons are that it burns very quickly and does not produce the heat of hardwoods. Also, burning pine is usually characterized by exploding sap pockets that cause sparking, which it turn can cause creosote buildup in your chimney. Many people like to use a softwood like pine to get a fire started before switching over hardwoods once the fire is hot.

Fir
Probably the best conifer for firewood, Douglas Fir has a medium heating value and does not produce too much ash. Older trees are easy to split and easy to start. Fir does produce a moderate amount of sparking.

Douglas fir is commonly mixed with Lodgepole and Ponderosa or Yellow Pine and the combination makes a great firewood choice.

Firewood Ratings and Info

Species	Relative Heat	Easy to Burn	Easy to Split	Heavy Smoke ?	Throw Sparks ?	General Rating	Aroma	Weight of Seasoned Cord-lbs	Heat Producd per Cord M Btu
Douglas Fir	High	Yes	Yes	Yes	No	Good	.	.	20.7
White Fir	Low					Fair	.	.	14.6
Western White Pine	Low	Med/Exc	Yes	Med	No/Mod	Fair	Good	2,236	14.3
Sugar Pine	Low	Med/Exc	Yes	Med	No/Mod	Fair	Good	.	.
Ponderosa Pine	Low	Med/Exc	Yes	Med	No/Mod	Fair	Good	2,380	15.2
Pinyon Pine	High					Fair			22

Where to buy

2009 prices:
Bushwhackers Firewood - (530) 412-3663 Kings Beach/Truckee 
     Cord:  Almond $340,  $25 delivery
 1/2 cord:  Almond $195,  $25 delivery
     Cord: Hard - Soft mix $300 $25 delivery
2008 prices:
Muschetto's Firewood - (916) 725-9663 7108 Antelope Rd
  1/2 Cord: Almond $209, Prem Oak $220, White Oak $219, Walnut $149
Bushwhackers Firewood - (530) 546-8307 Kings Beach/Truckee 
     Cord:  Almond $360, walnut $315,  $35 delivery
 1/2 cord:  Almond $205, walnut $185,  $35 delivery
North Shore Firewood - Truckee (530) 546-5876
      Cord: Almond or Oak $400 + $40 delivery
  1/2 Cord: Almond or Oak $280 $40 delivery
2004-5 prices:
Muschetto's Firewood - (916) 725-9663 7108 Antelope Rd
   Almond $240, Prem Oak $290, White Oak $280,
Bushwhackers Firewood - (530) 546-8307 Kings Beach/Truckee 
   Almond $300, fir-pine $175, Mixed $250 $20 delivery
North Shore Firewood - Truckee (530) 546-5876
      Cord:  Almond $325, pine-fir $265, mixed $300 $30 delivery

• Creosote - A variety of products that include wood creosote, coal tar pitch, ... or the resin of the creosote bush (chaparral),
  A black tar-like byproduct of burning wood. It will condense on the inside of the flue or chimney and can cause chimney fires.
  This happens if the flue is cold enough for the condensation process to take place. There are many reasons such as:
  Burning the fire too cool;
  Using fuel whose moisture content is too high;
  Cooling or slowing down the flue gases too much with the damper;
  Etc.
• Seasoning - Storing the wood to dry. When wood is freshly cut, it is holding approximately 60% of its water content and wont be usable for a fire until the moisture inside drops to about 20% or lower. Youll need to let the wood dry for 6 months to 1 year for it to be seasoned. Some species may take longer, and your climate plays a role too.