This is a quickreference list of conversion factors used by the Bioenergy
Feedstock Development Programs at ORNL. It was compiled from a wide range of
sources, and is designed to be concise and convenient rather than
allinclusive. Most conversion factors and data are given to only 3 significant
figures. Users are encouraged to consult other original sources for independent
verification of these numbers. The following are links to Web sites we have
found useful (many universities worldwide maintain good guides and conversion
calculator pages):
Energy contents are expressed here as Lower Heating Value (LHV) unless
otherwise stated (this is closest to the actual energy yield in most cases).
Higher Heating Value (HHV, including condensation of combustion products) is
greater by between 5% (in the case of coal) and 10% (for natural gas),
depending mainly on the hydrogen content of the fuel. For most biomass
feedstocks this difference appears to be 67%. The appropriateness of using LHV
or HHV when comparing fuels, calculating thermal efficiencies, etc. really
depends upon the application. For stationary combustion where exhaust gases are
cooled before discharging (e.g. power stations), HHV is more appropriate. Where
no attempt is made to extract useful work from hot exhaust gases (e.g. motor
vehicles), the LHV is more suitable. In practice, many European publications
report LHV, whereas North American publications use HHV.

Energy units
Quantities

1.0 joule (J) = one Newton applied over a distance of one meter (= 1 kg m^{2}/s^{2}).

1.0 joule = 0.239 calories (cal)

1.0 calorie = 4.187 J

1.0 gigajoule (GJ) = 10^{9}
joules = 0.948 million Btu = 239 million calories = 278 kWh

1.0 British thermal unit (Btu) = 1055 joules (1.055 kJ)

1.0 Quad = One quadrillion Btu (10^{15}
Btu) = 1.055 exajoules (EJ), or approximately 172 million barrels of oil
equivalent (boe)

1000 Btu/lb = 2.33 gigajoules per tonne (GJ/t)

1000 Btu/US gallon = 0.279 megajoules per liter (MJ/l)
Power

1.0 watt = 1.0 joule/second = 3.413 Btu/hr

1.0 kilowatt (kW) = 3413 Btu/hr = 1.341 horsepower

1.0 kilowatthour (kWh) = 3.6 MJ = 3413 Btu

1.0 horsepower (hp) = 550 footpounds per second = 2545 Btu per hour = 745.7
watts = 0.746 kW
Energy Costs

$1.00 per million Btu = $0.948/GJ

$1.00/GJ = $1.055 per million Btu

Some common units of measure

1.0 U.S. ton (short ton) = 2000 pounds

1.0 imperial ton (long ton or shipping ton) = 2240 pounds

1.0 metric tonne (tonne) = 1000 kilograms = 2205 pounds

1.0 US gallon = 3.79 liter = 0.833 Imperial gallon

1.0 imperial gallon = 4.55 liter = 1.20 US gallon

1.0 liter = 0.264 US gallon = 0.220 imperial gallon

1.0 US bushel = 0.0352 m^{3} = 0.97 UK bushel = 56 lb, 25 kg (corn or
sorghum) = 60 lb, 27 kg (wheat or soybeans) = 40 lb, 18 kg (barley)

Areas and crop yields

1.0 hectare = 10,000 m^{2}
(an area 100 m x 100 m, or 328 x 328 ft) = 2.47 acres

1.0 km^{2}
= 100 hectares = 247 acres

1.0 acre = 0.405 hectares

1.0 US ton/acre = 2.24 t/ha

1 metric tonne/hectare = 0.446 ton/acre

100 g/m^{2} = 1.0 tonne/hectare = 892 lb/acre

for example, a "target" bioenergy crop yield might be: 5.0 US tons/acre (10,000
lb/acre) = 11.2 tonnes/hectare (1120 g/m^{2})

Biomass energy

Cord: a stack of wood comprising 128 cubic feet (3.62 m^{3});
standard dimensions are 4 x 4 x 8 feet, including air space and bark. One cord
contains approx. 1.2 U.S. tons (ovendry) = 2400 pounds = 1089 kg

1.0 metric tonne wood
= 1.4 cubic meters (solid wood, not stacked)

Energy content of wood fuel
(HHV, bone dry) = 1822 GJ/t (7,6009,600 Btu/lb)

Energy content of wood fuel (air dry, 20% moisture) = about 15
GJ/t (6,400 Btu/lb)

Energy content of agricultural residues
(range due to moisture content) = 1017 GJ/t (4,3007,300 Btu/lb)

Metric tonne charcoal
= 30 GJ (= 12,800 Btu/lb) (but usually derived from 612 t airdry wood, i.e.
90180 GJ original energy content)

Metric tonne ethanol = 7.94 petroleum barrels = 1262 liters

ethanol energy content (LHV) = 11,500 Btu/lb = 75,700 Btu/gallon = 26.7 GJ/t =
21.1 MJ/liter. HHV for ethanol = 84,000 Btu/gallon = 89 MJ/gallon = 23.4
MJ/liter

ethanol density (average) = 0.79 g/ml ( = metric tonnes/m^{3})

Metric tonne biodiesel = 37.8 GJ (33.3  35.7 MJ/liter)

biodiesel density (average) = 0.88 g/ml ( = metric tonnes/m^{3})

Fossil fuels

Barrel of oil
equivalent (boe) = approx. 6.1 GJ (5.8 million Btu), equivalent to 1,700 kWh.
"Petroleum barrel" is a liquid measure equal to 42 U.S. gallons (35 Imperial
gallons or 159 liters); about 7.2 barrels oil are equivalent to one tonne of
oil (metric) = 4245 GJ.

Gasoline: US gallon = 115,000 Btu = 121 MJ = 32 MJ/liter
(LHV). HHV = 125,000 Btu/gallon = 132 MJ/gallon = 35 MJ/liter

Metric tonne gasoline = 8.53 barrels = 1356 liter = 43.5 GJ/t (LHV); 47.3 GJ/t
(HHV)

gasoline density (average) = 0.73 g/ml ( = metric tonnes/m^{3})

Petrodiesel = 130,500 Btu/gallon (36.4 MJ/liter or 42.8 GJ/t)

petrodiesel density (average) = 0.84 g/ml ( = metric tonnes/m^{3})

Note that the energy content (heating value) of petroleum products per unit
mass is fairly constant, but their density differs significantly – hence the
energy content of a liter, gallon, etc. varies between gasoline, diesel,
kerosene.

Metric tonne coal = 2730 GJ (bituminous/anthracite); 1519 GJ
(lignite/subbituminous) (the above ranges are equivalent to 11,50013,000
Btu/lb and 6,5008,200 Btu/lb).

Note that the energy content (heating value) per unit mass varies greatly
between different "ranks" of coal. "Typical" coal (rank not specified) usually
means bituminous coal, the most common fuel for power plants (27 GJ/t).

Natural gas: HHV = 1027 Btu/ft3 = 38.3 MJ/m^{3}; LHV =
930 Btu/ft3 = 34.6 MJ/m^{3}

Therm (used for natural gas, methane) = 100,000 Btu (= 105.5 MJ)

Carbon content of fossil fuels and bioenergy feedstocks

coal (average) = 25.4 metric tonnes carbon per terajoule (TJ)

1.0 metric tonne coal = 746 kg carbon

oil
(average) = 19.9 metric tonnes carbon / TJ

1.0 US gallon gasoline
(0.833 Imperial gallon, 3.79 liter) = 2.42 kg carbon

1.0 US gallon diesel/fuel oil
(0.833 Imperial gallon, 3.79 liter) = 2.77 kg carbon

natural gas (methane)
= 14.4 metric tonnes carbon / TJ

1.0 cubic meter natural gas (methane)
= 0.49 kg carbon

carbon content of bioenergy feedstocks: approx. 50% for woody
crops or wood waste; approx. 45% for graminaceous (grass) crops or agricultural
residues
