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170 Biomass Utilization, Limits of

requirements for biomass energy production were added Associated with the possibilities of increased employ-
to this, the amount of required water would be more than ment are greater occupational hazards. Significantly more
double to about 1 million l/yr. occupational injuries and illnesses are associated with
In addition to the unpredictable rainfall, the greatest biomass production in agriculture and forestry than with
threat to maintaining adequate fresh water supplies is de- either coal (underground mining), oil, or natural gas re-
pletion of the surface and groundwater resources that are covery operations. Agriculture and forestry report 61%
used to supply the needs of the rapidly growing human more occupational injury and illness rates than mining. In
population. Aquifers are being mined faster than the nat- terms of a million kilocalories of output, forest biomass
ural recharge rate and surface water is also not always has 14 times more occupational injuries and illnesses than
managed effectively, resulting in water shortages and pol- underground coal mining and 28 times more than oil and
lution that threaten humans and the aquatic biota that de- gas extraction. Clearly, unless safe harvesting practices
pend on them. The Colorado River, for example, is used and equipment are developed and used, increased forest
so heavily by Colorado, California, Arizona, other states, harvesting and agricultural production for energy will re-
and Mexico, it is usually no more than a trickle running sult in high levels of occupational injuries and increased
into the Sea of Cortes. medical expenditures and workman compensation.
The future development of major biomass energy pro-
grams will require large amounts of cropland suitable
E. Air Pollution
for biomass production and ultimately result in increased
The smoke produced when fuelwood and crop residues prices for some consumer commodities. The use of com-
are burned is a pollution hazard because of the nitrogen, modities, especially grains, for energy leads to compe-
particulates, and other polluants in the smoke. A report in- tition with traditional uses of these commodities. Thus,
dicated that although only 2% of the United States heating with increased grain use for ethanol production, inflation
energy comes from wood, and about 15% of the air pollu- of farm commodity prices could result. This in turn would
tion in the United States is caused by burning wood. Emis- increase farmland prices and make it more difficult for
sions from wood and crop-residue burning are a threat to new farmers to enter the business and for existing small
public health because of the highly respirable nature of the farmers to cope with higher rents, taxes, interest payments,
200 chemicals that the emissions contain. Of special con- and production costs. Food prices in supermarkets would
cern are the relatively high concentrations of potentially be expected to increase.
carcinogenic polycyclic organic compounds and particu-
lates. Sulfur and nitrogen oxides, carbon monoxide, and
aldehydes are also released, but with wood there are usu- VI. CONCLUSION
ally smaller quantities than with coal.
Certainly increased use of biomass as a fuel could pro-
vide the United States and the world with more renewable
V. SOCIAL AND ECONOMIC IMPACTS energy. A major limitation of biomass energy production
includes the relatively small percentage (average 0.1%)
In the future, if the world biomass is used as a major of light energy that is captured by the earth’s plant ma-
source of the world energy supply, shifts in employment terial. This governs how much biomass can be produced
and increases in occupational health and safety problems per unit land area. In addition to solar energy, suitably
can be expected. Total employment would be projected warm temperature conditions, adequate amounts of wa-
to increase 5% if about 11% of the United States energy ter, and the absence of pests are essential for plant growth.
needs were provided by biomass. This labor force would In North America, for example, plant growth only occurs
be needed in agricultural and forest production to plant, for approximately three months of the year. In arid regions
cut, harvest, and transport biomass resources and in the of the world plant growth is restricted only to periods of
operation of various energy conversion facilities. adequate rainfall.
The direct labor inputs for wood biomass resources are The removal of biomass, such as crop residues, from the
2–30 times greater per million kilocalorie than coal. In ad- land for energy production intensifies soil erosion, water
dition, a wood-fired steam plant requires 2–5 times more runoff, and soil nutrient losses. In addition, the conversion
construction workers and 3–7 times more plant mainte- of natural ecosystems into energy-crop plantations would
nance and operation workers than a coal-fired plant. In- alterand/orreducethehabitatandfoodsourcesforwildlife
cluding the labor required to produce corn, about 18 times and biodiversity.
more labor is required to produce a million kilocalories of At present, about half of the world’s biomass is har-
ethanol than an equivalent amount of gasoline. vested as food and forest products. Thus, there is a limit