# Hard coal unit

Physical unit
Unit name Hard coal unit
Physical quantity (s) Energy , internal energy , chemical energy
Formula symbol ${\ displaystyle SKE}$
dimension ${\ displaystyle {\ mathsf {ML ^ {2} T ^ {- 2}}}}$
In SI units ${\ displaystyle \ mathrm {1 \, kg \, SKE = 29 {,} 307 \; 6 \, MJ}}$
Derived from Calorific value of one kilogram of hard coal

The hard coal unit ( SKE ) is a unit of measurement used mainly in Central Europe, but not a legal unit for comparing the energy content of primary energy sources . The oil equivalent is more common internationally , so the SKE will hardly be found in English texts.

1 kg of SKE corresponds to the amount of energy that is released when burning 1 kilogram (kg) of (hypothetical) hard coal with a calorific value of exactly 7,000 kcal / kg; the ton SKE (t SKE) formed analogously to this is also common.

kg  SKE = 7,000  kcal = 29.3076  MJ = 8.141  kWh = 0.7 kg OE ( oil equivalent )

The hard coal unit was introduced for comparison purposes and was arbitrarily set to a realistic - approximately average - hard coal quality, which has a calorific value with a thousand-round value in kilocalories. The hard coal unit allows - after analyzing the quality of the delivered batches of fuel - for example, the storage level of a thermal power plant that can burn coal and oil to be clearly and easily indicated. For example, "1200 t TCE hard coal, 340 t TCE lignite and 560 t TCE heavy heating oil, so a total of 2100 t TCE". The same applies to purchase prices and efficiency assessments.

## Table overview

The following table contains approximate values ​​for average quality fuels that are used as guidelines by technicians. The calorific value of lignite fluctuates particularly strongly depending on its origin. Two different qualities are standardized for natural gas (L (ow) and H (igh)). Firewood can be damp and dry, hard and soft.

fuel Calorific value
in kg SCE
1 kg liquid gas 1.60
1 kg of gasoline 1.486
1 kg of crude oil 1.428
1 liter of crude oil
(d = 0.857 kg / L)
1.224
1 m³ natural gas
(mainly methane)
1.083
1 kg of hard coal 1.016
1 kg of petroleum coke 1,000
1 kg of hard coal coke 0.97
1 kg pitch coal 0.71
1 kg of brown coal briquettes 0.6570
1 m³ coke oven gas 0.57
1 m³ of mine gas 0.57
1 kg of firewood 0.500
1 kg substitute fuel
(from waste)
0.375
1 kg of brown coal 0.290