Energy, Environment, and
Industrial Development
Frederick H. Abernathy
Michael B. McElroy
Lecture 9
March 6, 2006
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Figure 3.1 The radiation budget of Earth’s surface-atmosphere system. Source:
Peixoto and Oort 1992
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Classification of terrestrial ecosystems
1.
2.
3.
4.
5.
6.
Tundra. No trees, grasses, mosses, lichens. Low
rainfall, low temperatures
Taiga or boreal forests. Dominated by conifers –
spruces, firs, larches, pines. Trees less than 30m
high. Covers much of Canada and Northern Eurasia
Temperate deciduous forests. Maples, beeches, oak.
Source of hardwood. China, Japan, western Europe,
United States, southern Canada
Temperate rain forests. Moderate temperatures and
high precipitation. Redwoods, Douglas firs, western
cedars. Western US, western New Zealand
Temperate woodlands. Temperature similar to
deciduous forests but drier. New England to Georgia.
Parts of Caribbean
Temperate shrub lands. Dry, temperate, low stature,
chaparral
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Classification of terrestrial ecosystems
7.
Temperate grasslands. Regions too dry for
forests. North American prairies, steppes of
Eurasia, pampas of Argentina. Fire and
grazing necessary for persistence of grasses
8. Tropical rain forests. High average
temperature relatively constant over year.
High, frequent, rainfall. Amazon basin,
Indonesia, Malaysia.
9. Tropical seasonal forests and savannas.
High relatively constant average
temperature. Abundant, but seasonal,
rainfall. Savannas dominate at lower rainfall.
10. Deserts. Rainfall < 0.5m/year
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http://edcdaac.usgs.gov/glcc/gifs.asp
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http://edcdaac.usgs.gov/glcc/gifs.asp
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Spring, Feb. 21-Apr. 21, 2001
Fall, Aug 21-Oct. 21, 2000
Summer, May 21-Jun. 21, 2000
Winter, Nov 21- Jan. 21, 2001
http://earthobservatory.nasa.gov/Newsroom/EVI_LAI_FPAR/
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Perfectly dry wood (0% moisture) can provide
as much as 8660 BTU/lb
Live wood contains a large amount of H2O.
Even when well seasoned, the moisture content
is significant ~ 20%
Significant heat is expended to evaporate the
water content of the wood and to raise its
temperature to the typical stack gas
temperature (~ 400 F). Energy required to
evaporate 1 lb of water = 1050 BTU
A realistic estimate of the energy available from
well seasoned wood is about 6050 BTU/lb or
13,367 BTU/kg
Approximately half of the wood is represented
by carbon. Thus, energy available is 12,100
BTU (lb C)-1 or 26,734 BTU (kgC )-1 = 2.67x104
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The photosynthetic process may be
represented as Light + CO2 + H2O  CH2O +
O2
Respiration (or decay) describes the reverse
process CH2O + O2  CO2 + H2O + energy
Gross uptake of C by photosynthesis at
Harvard Forest today amounts to about 11 tons
C ha-1 yr-1. 1 hectare (ha) = 2.47 acres
Most of the carbon taken up is respired. Only
about 25% is converted to organic matter, half
of which is above ground, half below. This
constitutes the net uptake.
Carbon available for sustainable harvest:
1 1
  11 tons C ha-1 yr-1 = 1.4 tons C ha-1 yr-1
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4
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Abernathy estimated that in 1800 people used
about 5.5 cords of wood per person per year.
Energy content of a cord he took as 20x106
BTU
Implies energy use per person per year of 5.5 x
20 x106 BTU = 110 x106 BTU
Carbon required to supply this energy
110 x10 6 BTU
1.1x10 8

kgC  4.1x10 3 kgC
1
4
26734 BTU (kgC)
2.67 x10
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Each person required 4.1 metric tons of C per
year, equivalent to about 8 metric tons of dry
wood or more than 15 tons of wood harvest
To apply needed carbon by sustainable harvest
each person would need
4.1ton C yr 1 person 1
 2.93ha person -1  7.25 acres person -1
1
1
1.4ton C ha yr
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Approximately 11% of the total global
land area is devoted to crops: about
15x106 km2 = 1.5x109 ha
If all of this land were devoted to
sustainable forestry with yields quoted
here, the carbon yield would amount
to 2.1x109 tons C yr-1
At a consumption rate of 4.1 tons C
(person)-1 yr-1, this could supply 512
million people
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There are indications that mid-latitudes of
the N. hemisphere are currently
accumulating carbon at a rate of about
2x109 tons C yr-1
Taking the 1800 per capita demand as 4.1
tons C yr-1, it follows that this would be
sufficient to supply (2/4.1) x 109 people or
487 million people at the 1800 consumption
rate.
Current fossil fuel use is about 6x109 tons C
yr-1 or about 1 ton C/person
US consumption per capita is about 4 ton C
yr-1 (person)-1
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Nutritional energy requirement for a typical
human  40 kcal day-1 (kg of body wt)-1
Energy requirement per unit of body mass for an
insect is about 10x higher than for a human or
about 20x higher for a small bird
Nutritional energy requirement for a typical 70 kg
adult human 
70 x 40 kcal day-1 = 2.8x103 kcal day-1;
1 kcal = 4 BTU
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Nutritional energy requirement for a typical 70 kg
adult  1.1x104 BTU day-1 
1.1x104 x 3.65x102 BTU yr-1 = 4x106 BTU yr-1. Allowing
for domestic animal feed  ~ 15 x106 BTU yr-1
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This compares with the energy demand for wood
per person per year in 1800 of 110x106 BTU
Energy/food factor = 28 or ~ 7 allowing for
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Estimate for carbon incorporated globally
in trees  3x109 tons C yr-1
How many people could this support at
utilization rate in 1800 New England?
About 0.7 billion (3x109/4.1)
Current global consumption of carbon in
fossil fuel is about 6x109 ton C/yr, roughly
twice the carbon potentially available from
trees
But, large amount of energy required to
harvest the trees. Plus transportation and
seasoning
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What is the better economic choice, to
grow food or timber?
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Timber is sold in units of board feet
1 board foot = 1 foot x 12 inches x 1 inch
Assuming a density of 1 g cm-3, the mass of a
board food is about 0.25 kg
Price for softwood: $35~$305/1000 board feet;
price for hardwood: $230~$580/1000 board feet
Take $300/1000 board feet as average 
timber worth $1200/metric ton
Rice costs $0.48/lb  $1.10/kg  $1100/metric
ton
It would appear that wood and food are
comparable as investments!
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Wood in English History
A Forest Journey, John Perlin, Harvard Univ. Press, 1991
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England was industrially relatively backward
in early 1500s. Henry VII built only four ships
for the Royal Navy during his reign (14851509)
Imported salt, iron, dyes, glass and arms
from continent
Change in 1530s. Concern about
Spanish/French intention to depose Henry
VIII (1509- 1547)
Development of arms industry in Sussex.
England is forefront of arms race to 1550
To produce 1 ton of bar iron required 48
cords of wood. Beginning of English
deforestation
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Wood in English History
A Forest Journey, John Perlin, Harvard Univ. Press, 1991
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Prior to Elizabeth I, England’s ships were
mostly made elsewhere or were hired.
Elizabeth took steps to promote domestic
industry. Subsidies for large ships, fishing,
policies on wine importation
To build a large warship took 2000 oaks
which had to be more than 100 years old.
Increased wood demands for iron, copper,
glass, construction. Wood becomes scarce.
James I prescribes permissible uses of
timber (houses, glass etc)
English reach to Ireland for new sources of
wood
Great fire of London, 1666
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Wood in English History
A Forest Journey, John Perlin, Harvard Univ. Press, 1991
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John Houghton proposed a strategic timber
reserve: “in times of peace, enough might be
laid up for war and I believe that once a tenyear store was gotten, we never need fear
the want of timber…when we are so
prepared, we need care for nobody”
Growth in use of wood for rail carriages,
mining, canal building, mills, water wheels
Abraham Darby develops method to use
coked coal rather than charcoal for metal
smelting. First coal-fired iron furnace in 1754
England moves from wood to coal age
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Diamond’s view of factors that can lead
to the collapse of a society
Collapse, Jared Diamond, 2005, Viking Penguin, member of
Penguin Group
1. Damage people inadvertently inflict
on their environment
2. Climate change
3. Hostile neighbors
4. Decreased support by friendly
neighbors
5. Society’s response to problems
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