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The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The calorific value is the total energy released as heat when a substance undergoes complete combustion with oxygen under standard conditions.
The calorific value of both the sapwood and heartwood is excellent, being reported to be 4,908 kcal/kg and 5,181 kcal/kg, respectively. As a fuel wood, it is grown on a 10- to 15-year rotation. The tree has excellent coppicing ability, although a loss of vigor after two or three rotations has been reported.
The wood can already be used after 6 days. [2] Its calorific value is around 4720 kcal/kg. [ 5 ] The yield is long-term high: Calliandra calothyrsus can be harvested during 10 to 20 years.
The energy content of wood pellets is approximately 4.7 – 5.2 MWh/tonne [43] [44] (~7450 BTU/lb), 14.4-20.3 MJ/kg. [45] None of these three sets of values come even close to agreeing. High-efficiency wood pellet stoves and boilers have been developed in recent years, typically offering combustion efficiencies of over 85%. [ 46 ]
The contribution of the muscle to the specific heat of the body is approximately 47%, and the contribution of the fat and skin is approximately 24%. The specific heat of tissues range from ~0.7 kJ · kg−1 · °C−1 for tooth (enamel) to 4.2 kJ · kg−1 · °C−1 for eye (sclera). [13]
Lignite (derived from Latin lignum meaning 'wood'), often referred to as brown coal, [1] is a soft, brown, combustible sedimentary rock formed from naturally compressed peat.It has a carbon content around 25–35% [1] [2] and is considered the lowest rank of coal due to its relatively low heat content.
Wood harvesting and transport operations produce varying degrees of greenhouse gas pollution. Inefficient and incomplete combustion of wood can result in elevated levels of greenhouse gases other than CO 2, which may result in positive emissions where the byproducts have greater Carbon dioxide equivalent values. [17]
Thus methane has an HHV (Higher heating value) of 55.50 MJ/kg, the highest value of common fuels. Diesel fuel has an HHV value of 44.80 MJ/kg and anthracite coal a value of 32.50 MJ/kg. Moisture and ash-free firewood has a lower value of 21.70 MJ/kg while dry peat has the lowest value of all common fuels of about 15.00 MJ/kg.