Biomass Fuel Values and Information

References:
Novel Power Sources for Survival Shelters (Contract OCD-OS-62-243) March 1963 (3.9~ MB PDF)

Coals/Cokes

General Remarks:

Coals and coke store well. The main difference in storage characteristics is the tendency towards spontaneous combustion. Anthracite coals have the least tendency while bituminous coals have less tendency for spontaneous combustion than lignite. The property in cokes is a function of the coal from which they were prepared.

Coals lose part of their heating value during storage due to the sublimation of some of their volatile material. The loss recorded by some investigators is at a rate of 0.5 to 1 percent per annum. A 5.5 percent loss in three years has been reported in one case. The loss rate of heating value is much less for coal stored in confined unvented places.

Storage Precautions:

Emergency Measures for Fires:

In the event of excess heat or spontaneous combustion, the coal/coke pile can be flooded with water, or dry ice can be placed atop the pile. The dry ice would generate gaseous CO2 which would replace the oxygen nearby, preventing combustion from occurring.

Anthracite Coal

Calorific Value: 14,250 BTU/lb (
Specific Volume: 37-40~ cubic foot/ton

Notes: This is a hard, dense coal which does not produce dust on handling, but is somewhat difficult to ignite. Upon burning, produces a clean fire with little ash.

Bituminous Coal

Calorific Value: 9,180 to 15,240 BTU/lb
Specific Volume: 41-45 cubic foot/ton

Notes: This includes many types of coal, which vary considerably in composition, properties, and burning behavior. The volatile matter varies from 18.7 to 40.8 percent and the moisture content from 2.2 to 26.9 percent.

Lignite Coal

Calorific Value: 7,400 BTU/lb

Notes: This coal has the highest moisture content (39.1 percent); the volatile matter is 29.5 percent.

Coke(s)

Calorific Value: 14,500 BTU/lb (typically)
Specific Volume: 90-100 cubic foot/ton

Notes: The properties of cokes depend on the type of coal from which they are produced.

Wood

Definition of Wet / Dry Wood

Wood with more than 30% moisture is considered wet. Freshly cut wood has 30-50% of moisture, while one year old dried wood has 18-25% moisture.

Definition of a Cord of Wood:

A cord of wood is a 4 by 4 by 8 ft. pile and contains the following percentages of solid material:

Timber cords 74.07%
Firewood cords 69.44% (diam. over 6 inch)
Bellet cords 55.55% (diam, over 3")
Brushwood cords 18.52% (diam. less than 3")
Roots 37%

Heating Values of Wood

Type

Weight (lb/cord)

Heating Value (BTU/lb)

Equivalent weight of 13,500 BTU/lb Coal

green

Air-dried

Green

Air-dried

green

Air-dried

Ash, white

4,300

3,800

4,628

5,395

0.343

0.400

Beech

5,000

3,900

3,940

5,359

0.292

0.397

Birch, yellow

5,100

4,000

3,804

5,225

0.282

0.387

Chestnut

4,900

2,700

2,633

5,778

0.195

0.428

Cotton wood

4,200

2,500

3,024

6,000

0.224

0.444

Elm, white

4,400

3,100

3,591

5,710

0.266

0.423

Hickory

5,700

4,600

4,053

5,391

0.300

0.399

Maple, Sugar

5,000

3,900

4,080

5,590

0.302

0.414

Maple, red

4,700

3,200

3,745

5,969

0.277

0.442

Oak red

5,800

3,900

3,379

5,564

0.250

0.412

Oak white

5,600

4,300

3,972

5,558

0.294

0.412

Pine, yellow

3,100

2,300

7,097

9,174

0.526

0.680

Pine, white

3,300

2,200

4,226

5,864

0.313

0.434

Walnut, black

5,100

4,000

4,078

4,650

0.302

0.344

Willow

4,600

2,300

2,370

5,870

0.176

0.435

Miscellaneous Solid Fuels

Heating Values of Miscellaneous Fuels

Fuel

Approximate Density (lb./ft3)

Approximate Higher Heating Value (Btu/lb.)

Sawdust Briquets

75 - 80

8,100

Straw


6,000

Corn


8,000

Cottonseed Hulls

15

7,100

City Refuse

40-44

8,800

Fuel Oils

Storage Notes: Storage of fuel oils for long periods of time results in gum formation in the tanks. Storage space required is 0.134 ft3 per gallon. If you store light grade fuel oil in buried tanks which are vented to the atmosphere, about 0.2 percent of oil will be lost each year due to evaporation losses. Ventless tanks will eliminate this loss.

No.1 Fuel Oil

Calorific Value: 136,000 to 139,000 BTU/gallon

No.2 Fuel Oil

Calorific Value: 139,500 to 140,500 BTU/gallon