ENERGY SOURCES—ALTERNATIVES 299
The medium-range forecast for the year 2000, summarized
in Table 1 indicates a shift in energy demand to electricity
generated in centralized plants with its share of direct resource
usage increasing from about 22% in 1968 to 43% in 2000.
This shift is apparent in current trends with the demand for
total energy growing at about 4% per year while the demand
for electricity is growing at around 7% per year not consider-
ing the question of future acceptance. Nuclear power is pro-
jected to account for over half of the electrical generation in- Such changes in energy demand patterns are seen to
have profound effects on the amount of resources consumed
and, consequently, on environmental effects. For example, in
the case of space heating which constitutes a growing market
for electrical energy, fossil resources may be used directly for
their thermal effect at an average efficiency about twice that
involved in the conversion to electricity in central station power
plants. This results in a doubling of the amount of fossil fuel
that must be burned to provide a given amount of space heat
to the consumer. Although this substitution would be expected
to result in the production of more wastes and emissions, it
may be justifiable on the basis of the economies of scale that
are at work in the centralized operation, which permit better
control of emissions, and the opportunity it provides to utilize
the more abundant nuclear fuels which cannot be applied eco-
nomically in small decentralized conversion systems.
In a different example, for space heating and probably
also some demand of process heating thermal power plants
(coal, lignite, and nuclear) could be used by the double pur-
pose electricity generating and district heating system, that
would increase substantially the efficiency of such power
plants, involving however the high investment costs for the
take-out of heat in the power plants and the long distance
tube circulating system to the main demand centers.
The demand indicated in Table 1 for petroleum in 1968
in the various sectors requires more detailed attention since
this energy resource is consumed in a variety of product
forms. The total demand for petroleum products was 4.9
10 9 barrels and Table 3 shows how this total breaks down
among the various products. The end use of most of these
is self-evident and it may be seen that less than 2% of the
product was consumed as petrochemical feedstock. Diesel
fuel for mobile and stationary power plants is included along
with the lighter fuel oils in the distillate fuel oil category.
Naphtha-type jet fuel is generally used in military aircraft
while the kerosine-type fuel is used in civil aircraft.
The non-energy demand for natural gas as petrochemi-
cal feedstock and in the production of carbon black for
the rubber industry accounted for about 2½% of the total
demand for that resource. In the case of coal, about half of
the resources used in the industrial sector were consumed
as coke, carbonized from coal. About 1% of the total coal
demand is consumed as industrial raw materials for the pro-
duction of crude light oil and coal tars. There is much con-
cern over the depletion of petroleum and natural gas for energy
purposes when the demand for these materials, as organic
molecular building blocks in the petrochemical industry, is
growing rapidly and will expand further as natural mineral
resources are depleted and must be replaced in their markets
TABLE 1
Total US energy consumption by fuel and consuming sector
(trillions of Btu’s in direct fuels used)19683 20004
(actual) (projected)Household and commercial:
Gas 6,451 19,066
Petroleum 6,581 2,000
Coal 568
Total 13,600 21,066
Industrial:
Gas 9,258 17,504
Petroleum 4,474 13,090
Coal 5,616 2,000
Total 19,348 32,594
Transportation:
Gas 610 1,000
Petroleum 14,513 41,649
Coal 12 —
Total 15,135 42,649
Electric utilities:
Gas 3,245 4,128
Petroleum 1,181 861
Coal 7,130 18,720
Hydro (coal equiv.) 2,359 5,056
Nuclear 130 43,526
Total 14,045 72,291
Miscellaneous:
Gas — —
Petroleum 295 —
Coal 1 —
Total 296 —
Total Consumption 62,424 168,600TABLE 2
Utility electricity distribution by consumer sector
(trillions of Btu’s in electrical form)19683 20004
Household and commercial 2,469 20,045
Industrial 2,043 10,793
Transportation 18 100
Total 4,530 30,938The forecast methodology with its multiple “demand sce-
narios” has led to the development of computerized demand
models with more or less comfort on the input side. Such
models are useful for the analysis of different “scenarios”
and consequences for the energy application. The uncer-
tainty of some factors of the consumer market recommends
to limit the comfort of full particulars of demand models.C005_006_r03.indd 299C005_006_r03.indd 299 11/18/2005 12:05:46 PM11/18/2005 12:05:46 PM