Summary

Specific energy and energy density are useful measures of the energy that will be released from a given weight or volume of fuel when it is burned. This article provides a quick reference for common values of specific energy and energy density.

Definitions


$E_{d}$	:	Energy density
$E_{s}$	:	Specific energy
$E$	:	Energy released during combustion
$m$	:	Volume
$V$	:	Volume

Introduction

The Heat of Combustion of a product measures the energy released when that substance is burned in air, this information is often presented in units of $kJ/mol$ .

The specific energy and energy density of a fuel provide practical measures of the energy content of a fuel in units more commonly used in the storage and handling of these substances (energy per weight and volume).

Specific Energy

Specific energy is the energy per unit mass of a fuel.

$E_{s} = \frac{E}{m}$

Energy Density

Energy density is the energy per unit volume of a fuel.

$E_{d} = \frac{E}{V}$

Typical Values of Specific Energy and Energy Density

The Specific Energy and Energy Density of some common fuels and combustible compounds are given below. Note the values are negative as they represent the energy lost from the substance as it burns. The surrounding environment will gain this amount of energy.

Common Fuels

Fuel	Density (kg/m^3)	Specific Energy (MJ/kg)	Energy Density (MJ/m^3)
Gasoline	716	-47.3	-33,867
Kerosene	830	-46.2	-38,346
Diesel Fuel	830	-44.8	-37,184
Ethanol	784	-29.7	-23,278
Coal (Anthracite)	1,350	-27	-36,450
Methanol	787	-22.7	-17,855
Wood	600	-15	-9,000
Coal (Lignite)	801	-15	-12,015

Compounds

Type	Fuel	Formula	Density (kg/m^3)	Specific Energy (MJ/kg)	Energy Density (MJ/m^3)
Alcohol	Methanol	$C_H3OH$	787	-22.7	-17,855
Alcohol	Ethanol	$CH_3CH_2OH$	785	-29.7	-23,278
Alcohol	1-Propanol	$CH_3(CH_2)_2OH$	800	-33.6	-26,902
Alcohol	2-Propanol	$CH_3CH(OH)CH_3$	781	-33.4	-26,068
Alcohol	1-Butanol	$CH_3(CH_2)_3OH$	806	-36.1	-29,107
Alcohol	1-Pentanol	$CH_3(CH_2)_4OH$	816	-37.8	-30,817
Alcohol	1-Hexanol	$CH_3(CH_2)_5OH$	814	-39	-31,732
Alcohol	1-Heptanol	$CH_3(CH_2)_6OH$	822	-39.9	-32,809
Alcohol	1-Octanol	$CH_3(CH_2)_7OH$	825	-40.7	-33,545
Alkane	Methane	$CH_4$	423	-55.6	-23,529
Alkane	Ethane	$C_2H_6$	545	-51.8	-28,246
Alkane	Propane	$C_3H_8$	585	-50.3	-29,449
Alkane	Butane	$C_4H_{10}$	601	-49.5	-29,729
Alkane	Pentane	$C_5H_{12}$	621	-48.7	-30,223
Alkane	Hexane	$C_6H_{14}$	655	-48.3	-31,633
Alkane	Heptane	$C_7H_{16}$	680	-48.1	-32,690
Alkane	Octane	$C_8H_{16}$	698	-47.9	-33,433
Alkane	Nonane	$C_9H_{16}$	714	-47.7	-34,086
Alkane	Decane	$C_{10}H_{18}$	726	-47.6	-34,581
Alkane	Undecane	$C_{11}H_{20}$	737	-47.5	-35,039
Alkane	Dodecane	$C_{12}H_{22}$	745	-47.5	-35,378
Alkane	Hexadecane	$CH_3(CH_2)_{14}CH_3$	770	-47.3	-36,388

Specific Energy and Energy Density of Fuels