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Friday, 30 November 2012

Units Begin The Story

Greek mythology has it that the immortal Titan Prometheus stole fire from his brothers, the gods on Mt. Olympos, and brought this to Man to dispel our darkness and suffering. Legend or not, Man has known how to generate fire and heat, using external tools and implements, for millennia. Our ability to generate, harness and channel increasing amounts of energy has marked our progress as a civilization since the dawn of time. Our ability to manipulate energy on a grand scale, is a unique human gift distinguishing us from any other species on the planet.

Prometheus (painting by F.H Fuger)

This blog is meant to serve as a quick-and-dirty refresher for those who do have such background, and as a primer for those who do not, but need to get up to speed relatively quickly.

For quick energy conversions, you can go directly HERE
Relevant Units for Solid Fuels

The British Thermal Unit (Btu)
One of the oldest and still most commonly used energy units is the BTU, or British Thermal Unit. The Btu is most used as a measure of the calorific (or heat energy) content of fuel sources such as coal, biomass etc.  

A Btu is defined as the amount of heat required to raise the temperature of one (1) pound (lb) of water by 1°F (one Fahrenheit, or 0.556°C) at atmospheric pressure. It is approximately the energy given out by 1 match, or the energy required to lift 1 pound of weight by 778 feet (hence also defined as 778 ft-lb). It can be written either as BTU, Btu, Btu, or Btu.

One million Btu’s (1,000,000) are described as 1 MMBTU (MM as an abbreviation for 1 million). Do not confuse that with 1 MBTU, which is one thousand (1,000) BTUs.

The Btu is still very important because most fuel sources are still described in terms of the amount of heat energy extractable per mass of the fuel. Most fuels are easily compared by looking at their MMBtu/MT – that is, the amount of Btu’s available in 1 metric ton of the fuel.

Quick side-note on tons: 1 MT or metric ton, is defined as 1000 kg, or 2205 pounds (lbs). This is different from a Long Ton (2240 lbs, 1016.05 kg), which is also known as an Imperial Ton. There is also the Short Ton (an American term) ton which is 2000 lbs (907.2 kg) and is frequently what is meant in the US when coal producers refer simply to “tons”.


Anthracite coal: Anthracite is the oldest type of coal, and has a very high carbon content. Typically has energy content of >28 MMBTU/MT, the highest of any coal type.

Coal upon mining

Bituminous Coal: This is the second highest-value type of coal. Coals of this type typically have energy content values of 24 – 28 MMBTU/MT.

Sub-Bituminous Coals: This is one grade of coal less energetically rich than bituminous coal and generally 18-24 MMBTU/MT.

Lignite: This is the youngest form of coal and its chemical structure is not yet as carbon-rich as the other forms – this type of coal typically has energy content values of 14 – 18 MMBTU/MT.

Quite often, energy content values, especially for coal are given as BTU/lb, and in order for best comparison must be converted into MMBTU/MT.

In order to convert to MMBTU/MT, we multiply the value if BTU/lb by the following fraction
BTU/lb à MMBTU/MT = Value in BTU/lb  X (2205/1,000,000)

Energy content of coal with specification of 11,000 BTU/lb in MMBTU/MT:
1 MT  = 2205 lbs

Hence energy contained therein= 2205 lbs/MT  X 11,000 Btu/lb = 24,255,000 BTUs in that 1 MT. This is equal to 24.26 MMBTU.

Hence 11,000BTU/lb = 24.26 MMBTU/MT.

Formula: To convert Btu/lb to MMBTU/MT: Multiply the Btu/lb by 0.002205.

One MJ is one million (1,000,000) Joules.
1 BTU is equivalent to 1055 Joules (or 1.055kJ)

Hence fuel source with calorific content of 15 MJ/kg:
15 MJ = 15,000,000 Joules  = 14,218 BTUs, or 0.01421801 MMBTU, contained in 0.001 MT.

Hence 15 MJ/kg = 14.22 MMBTU/MT.

Formula: To convert MJ/kg to MMBTU/MT: Multiply the MJ/kg by 0.95.

Relevant Units for Gas
Gas is typically not described in terms of MMBTU/MT, primarily because as a gas, it is easier to describe calorific content by volume vs by a one-ton mass. The typical measure of energy content in gas is by cubic feet.
1 cubic foot volume

M – represents 1,000. Hence Mcf means one thousand cubic feet (1000 cf).
MM – represents 1,000,000
MMBtu – is 1,000,000 Btus.

1 Therm – is 100,000 Btus

The average heat content of natural gas (pipeline-quality natural gas) is:
1 cf  (1 ft3)= 1023 Btu

1 cf  (1 ft3) ~ 1.08 MJ

1 Mcf = 1.023 MMBTU

Now, gas is also measured in cubic meters. 1 cubic meter of gas is the equivalent of 35.3 cubic feet of gas and has energy content of 36.1 MBTU

1 m3 = 35.31 ft3 = 36,126 BTU

For pricing/cost comparisons, to convert:

$ per Mcf divided by 1.023 = $ per MMBtu

$ per MMBTU multiplied by 1.023 = $ per Mcf

Relevant Units for liquid fuels
1 standard barrel  = 42 US gallons (vs British Imperial gallons) = 5,800,000 Btu, or 5.8MMBtu for crude.

Wine vs Oil Barrels

1 standard barrel = 158.984 liters
·       the 42-US gallon size of barrel as a unit of measure is largely confined to the American oil industry, since other sizes of barrel were used by other industries in the United States. Nearly all other countries use the metric system. Many oil producing countries use the American oil barrel.

·      Barrels per day (abbreviated BPD, BOPD, bbl/d, bpd, bd or b/d) is a measurement used to describe the rate of crude oil production or consumption by an entity. For example, an oil field might produce 100,000 bpd, and a country might consume 1 million bpd.

·       The abbreviations 1 Mbbl and 1 MMbbl have historically meant one thousand and one million barrels respectively.

·       For CRUDE OIL, 1 barrel = 5,800,000 Btu, or 5.8MMBtu (based on U.S. production, 2009)

o   NOTE: 1 barrel of Gasoline or Diesel will have a slightly different energy content

· For Gasoline, 1 gallon = 124,238 Btu, or 1 barrel Gasoline = 5,218,999 Btu

· For Diesel, 1 gallon = 138,690 Btu, or 1 barrel Diesel = 5,825,022 Btu

There are 3.785 liters in a US gallon and 4.55 liters in British gallon.

·       In 2011 for example, Ghana’s first full year of oil production, the average productivity was about 70,000 bpd. Other countries such as Nigeria produce close to 2.5 million barrels per day (2.5 MMbpd).

1 cubic meter of concrete
1 cubic meter (sometimes abbreviated to cu m, m3, CBM, (say of diesel, or crude oil) = 1000 liters exactly.

Therefore, 1 barrel, which is 42 US gallons, or 158.984 liters, is equal to 0.158 CBM
1 barrel = 0.158 m3, or 0.158 CBM

And, consequently, 1 CBM = 6.289 barrels of Oil

Various Energy Sources


Author: Victor K Mallet, Managing Partner, Arrakis Group -