Encyclopedia of Environmental Science and Engineering, Volume I and II

ENERGY SOURCES—ALTERNATIVES 305

carry petroleum products. In 1969 there were 1007 reported

spills of oil in quantities over 100 bbl each. Vessels were

identified as the source of 53 of the seaspills, 331 were

from shore facilities, and 144 were unidentified. Individual

discharges can be quite large however. In 1967 the tanker

Torrey Canyon ran aground and discharged approximately

400,000 bbl of crude oil into the sea. It has been estimated^21

that the oil well blowout in the Santa Barbara channel in

1969 released about 75,000 bbl of oil by the 100th day of

discharge. Smith^22 has outlined methods of dealing with spills

after they have occurred that have been applied in the United

Kingdom, including skimming, absorption, jelling, sinking,

and emulsification.

Acid mine drainage, consisting of sulfuric acid and iron

compounds formed by the reaction of water and air with sulfur-

bearing minerals, contaminates local streams in coal mining

areas. Martin,^23 in 1968, estimated that over 4 million tons of

polluted water was released annually in the United States to

about 11,000 miles of streams and other receiving waters from

both abandoned and active mines. Control measures include

eliminating the source of polluted water drainage by seal-

ing off underground mines and restoring the surface of strip

mines, and by collection and treatment of the drainage.

The petroleum- and coal-producing industries, in 1964,

discharged about 7.3 
 10 12 gal of industrial waste, or about

10% of the total discharge of industrial waste water. This

waste involved 500 
 10 6 lb of biochemical oxygen demand

(BOD), only about 2% of the total industrial waste water

BOD. These industries also required 1.2 
 10 12 gal of cool-

ing water in the same year which was 2.4% of the total indus-

trial cooling water demand. Electrical utilities accounted

for 81.3% of the total demand by using 40.7 
 10 12 gal of

cooling water. This water is returned to the environment in

a heated condition, which reduces the amount of dissolved

oxygen that can be retained and thus has an effect similar

to oxygen demanding wastes, but it is not otherwise con-

taminated. The need for cooling water is discussed in a more

general context, along with alternate means of heat rejection,

in the following section.

Thermal Effects

Heat must be rejected from all thermodynamic power cycles

in quantities that depend on the efficiency of the energy

conversion operation. The primary sources of waste heat

are central station power plants, which can reject heat from

their condensers to water or to the atmosphere through cool-

ing towers, and automotive power plants, which discharge

their waste energy to the atmosphere in exhaust gases.

Atmospheric discharges of thermal energy can lead to local

meteorological effects while discharges to water can have

effects on the marine ecology.

In a 1000 MW (electrical output) fossil fuel power plant

of 40% thermal efficiency, about 1275 MW of thermal

energy must be rejected to the condenser coolant while about

225 MW is discharged directly to the atmosphere in the flue

gas. A nuclear power plant of the same electrical capacity

operating at 33% efficiency must reject all of its waste heat,

2000 MW, to the condenser coolant.

Discharges of waste heat can be controlled by improv-

ing the thermal efficiency of power plants, and the severity

of local effects may be reduced by distributing the waste

energy in large quantities of air or water. Many regulatory

agencies have placed restrictions on the allowable tempera-

ture difference between inlet water and the water returned to

the marine environment. Cooling ponds may be employed in

such instances to hold up the effluent water until it has cooled

to the allowable discharge temperature. Applications for this

“waste” energy have been proposed,^24 including space heating

and refrigeration in urban areas, thawing of ice-bound sea-

ways, agricultural use to stimulate growth and to extend the

growing season, and in aquaculture to stimulate the growth of

algae, shellfish, and other potential marine food sources.

The use of waste heat for district heating systems may

have a good chance to be applied on a large scale, although

this technology needs a relatively high initial investment.

Radiation

There has been little addition to natural radiation levels in the

environment as a result of energy related activities, exclud-

ing nuclear weapons testing as a source.

In the nuclear industry radiation problems begin with the

mining of uranium-bearing ores. The alpha particle emitters,

particularly radon gas, in the uranium-238 decay chain that

ends with stable lead-206 pose the major health problem.

Radon is chemically inert and diffuses from rock surfaces

into the mine atmosphere where it and its daughter products

can be inhaled by workers. Exposure standards and control

measures have been published by the Bureau of Mines.^25

Mine tailings also contain these radiation sources which

complicate the disposal of these solid wastes.

The largest source of radioactive materials are the prod-

ucts produced by the fissioning of uranium and plutonium fuel

in nuclear reactors. These fission products are formed in the

encapsulated fuel elements and must be handled in the reactor

waste treatment system only in small amounts that may leak

from the elements during reactor operation. Other radioactive

materials found in the reactor system are isotopes produced by

the irradiation of materials of construction, corrosion products,

and coolant additives. The fission products must be handled in

the fuel processing plant where uranium and plutonium that

has not fissioned is recovered for use in new fuel elements.

Table 11 indicates the activity of the long-lived radioactive

materials that are generated in the fuel elements of a nuclear

reactor and that pose a long-term disposal problem. Isotopes

with a short half-life may be simply held-up until they decay

to a harmless product that may be released to the environment,

but the others must be chemically reacted and concentrated

for disposal by some other technique. The long half-life mate-

rials must be sequestered in a manner such that they cannot

be released to the environment for centuries. A most promis-

ing approach to long-term disposal under study by the Atomic

Energy Commission (AEC) involves the concentration of

radioactive wastes and their conversion into an inert solid form

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