Encyclopedia of Environmental Science and Engineering, Volume I and II

298 ENERGY SOURCES—ALTERNATIVES

are used at efficiencies of 60% to 75%, while fuels used

for transportation are converted first to thermal and then to

mechanical energy at an average over-all efficiency of about

25%. The source of the 1968 data is the Minerals Yearbook^3

while the projections are those of Morrison and Readling,^4

who developed a loglinear relationship between the major

subcomponents of energy demand and several independent

variables that are assumed to influence demand, such as;

population, economic indicators, and technological devel-

opments. Coefficients of the independent variables were to

be obtained by regression analysis using data for the period

1947 to 1965.

The year 2000 projection of a total energy resource

demand of 168.6 
 10 15 Btu is a medium range case, and

assumes a normal rate of improvement in energy conversion

efficiency and the continuation of present trends of competi-

tion and substitution in energy markets. Other projections

were made by Morrison and Readling on the basis of differ-

ent assumptions, including high- and low-range cases that

reflect changes in energy demand patterns and technologi-

cal developments anticipated in energy conversion systems.

The high-range case forecasts a demand of 209.4 
 10 15 Btu

in the year 2000 and assumes the establishment of an all-

electric economy, where electricity is generated in fossil,

hydroelectric, and nuclear power plants at an average effi-

ciency of 43% and is consumed in household, commercial,

and industrial sectors at 10% efficiency and in transportation,

with battery-driven vehicles, at an efficiency of 42%. The

low-range forecast is 106.5 
 10 15 Btu and assumes that

energy inputs to the household, commercial, and industrial

sectors are satisfied with electricity from fuel cells operating

at an efficiency of 75% with 50% recovery of waste heat,

and energy requirements in the transportation sector are

also provided by fuel cells but at an efficiency of 50%. This

again, is an all-electric economy but no central station power

generation is needed under these circumstances. Natural gas

was the fuel considered for all sectors in the low-range case,

however, alternative fuels suitable for fuel cells could also

be provided by hydrogen or methane produced by the gas-

ification of coal, or by hydrogen made by the electrolysis of

water. Of course such forecasts are highly speculative since

it is not certain that fuel cells will be economical in such

application in the next 30 years. Numerous other forecasts

of energy demand have been made and are summarized in

a review^5 performed by Batelle-Northwest for the Energy

Policy staff of the Office of Science and Technology (OST).

All of these forecasts neglected supply restraints and thus do

not reflect the effect of possible energy cost variations due to

shortages of resources, increased requirements for environ-

mental protection, and technological developments. None

indicate any significant exploitation of solar, geothermal or

tidal energy resources.

Energy resources

System

hardware

Refined

fuels

By-

products

Energy

Energy Goods and products

Wastes

Wastes

Agricultural

resources

Mineral

resources

Wastes:

Hydrocarbons

Ash

CO 2 and CO

SO 2

NOx

Radioactive

wastes

Waste energy

Energy conversion

1. Centralized
   2. Decentralized
   a. Stationary
   b. Mobile

Materials processing

1. Fuel refining
   2. Petrochemicals
   3. Food products
   4. Metal products
   5. Structural products


2. Textiles

Final consumption

1. Household
   2. Commercial


2. Industrial


3. Transportation

FIGURE 3 Materials flow diagram in economic activity.^2

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