Environmental Engineering Reference
In-Depth Information
large-scale industrial glass production needs only about 15 MJ/kg, mostly in the
form of natural gas. Salt production in interior locations—evaporating brines in
large wood-heated iron pans—was another inefi cient process consuming large
volumes of wood: a kilogram of salt required as little as 5 kg and as much as 40
kg of wood.
Residential consumption could reach very high levels in colder forested areas
(Sieferle 2001). In 1572, the Weimar court needed annually 1,300 cords of wood,
or some 3,000 m
3
, a volume that would require about 600 ha of coppice growth.
In the early eighteenth century the University of Königsberg allocated 70 m
3
of wood
for every employee, that is, at least 500 GJ per household, or as much as 100-125
GJ per capita. That was exceptionally high: during the eighteenth century, annual
wood consumption in Germany was typically on the order of 50-60 GJ per capita
(Sieferle 2001). The Austrian mean in 1830 was 73 GJ per capita (Krausmann and
Haberl 2002), and the residential demand was similar in the nineteenth-century
United States: household heating consumed up to 50 GJ per capita, and rising
industrial needs added as much or more. Schurr and Netschert (1960) estimated
that all i nal uses prorated to an average U.S. per capita consumption of nearly 100
GJ during the 1850s. In comparison, the contemporaneous Parisian rates were
minuscule as annual per capita fuelwood consumption fell from less than 15 GJ
(1.8 m
3
) in 1815 to less than 5 GJ by 1850 (Clout 1983).
Charcoal
Wood's bulk and often high moisture content made charcoal a preferred choice for
indoor combustion and a perfect reducing agent for smelting metals. Charcoal is a
slightly impure carbon with a high energy density of nearly 30 MJ/kg, but its mass
density is low, ranging from 115 kg/m
3
for charcoal made from pines to 189 kg/m
3
for fuel derived from tropical hardwoods. Charcoal burns without any particulate
or sulfurous emissions. In Japan, charcoal was burned in
kotatsu,
braziers placed
in pits (about 40 cm deep) cut into the l oor and covered with a table and a blanket:
this may have warmed legs and even an upper body clad in traditional Japanese
clothes, but left most of the room uncomfortably cold. In England, heating pots and
braziers remained the norm well into the early modern era when the large-scale use
of coal was common: the British House of Commons was heated by large charcoal
i re pots until 1791.
But household consumption of charcoal was a small fraction of the demand for
charcoal as metallurgical fuel, a reducing agent in smelting i rst the ores of color
