Coastal Thermal Pollution and Related Policy Issues in the United
States: An Overview. ©
By Brock McCracken
Coastal Policy Class
Dr Steffen Schmidt
Nova Oceanographic Center
© Copyright, Brock McCracken. Any citation must attribute this research to the author.
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INTRODUCTION
Thermal Pollution
Pollution is the contamination of Earth’s environment with materials that interfere with
human health, the quality of life, or the natural functioning of ecosystems (living
organisms and their physical surroundings). Although some environmental pollution is a
result of natural causes such as volcanic eruptions, most is caused by human activities.
Water Pollution is the contamination of streams, lakes, underground water, bays, or
oceans by substances harmful to living things. Water is necessary to life on earth. All
organisms contain it and some live in it and most drink it. Plants and animals require
water that is moderately pure, and they cannot survive if their water is loaded with toxic
chemicals or harmful microorganisms. If severe, water pollution can kill large numbers of
fish, birds, and other animals, in some cases killing all members of a species in an
affected area. Pollution makes streams, lakes, and coastal waters unpleasant to look at, to
smell, and to swim in. Fish and shellfish harvested from polluted waters may be unsafe to
eat. People who ingest polluted water can become ill, and, with prolonged exposure, may
develop cancers or bare children with birth defects.
The major water pollutants are chemical, biological, or physical materials that degrade
water quality.
Water is often drawn from rivers, lakes, or the ocean for use as a coolant in factories and
power plants. Almost half of all water withdrawn in the United States each year is for
cooling electric power plants. The cheapest and easiest method is to withdraw water from
a nearby body of surface water, pass it through the plant and return the heated water to
the same body of water. The water is usually returned to the source warmer than when it
was taken. This process is called once through cooling or wet cooling as opposed to dry
cooling. The water absorbs the excess heat of nuclear rods or other machinery and then
returned to the environment. See Figure 1.
Large inputs of heated water from a single plant or a number of plants using the same
lake, ocean or bay region, or slow-moving stream can have harmful effects on aquatic
life. This is called thermal pollution. Even small temperature changes in a body of water
can drive away the fish and other species that were originally present, and attract other
species in place of them. Thermal pollution can accelerate biological processes in plants
and animals or deplete oxygen levels in water. The result may be fish and other wildlife
deaths near the discharge source.
Thermal pollution can also be caused by the removal of trees and vegetation that shade
and cool streams. The deforestation of shoreline aggravates soil erosion and increases the
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amount of light that strikes the water. Soil erosion leads to muddy water, which lowers
the clarity of water, with the introduction of impurities in water, containing microbes and
dissolved minerals, which increase the light absorption from the atmosphere. The waters
increased light absorption will see a rise in the temperature of water from the heat energy
of light.
Figure 1. The figure depicts wet cooling or once through cooling tower versus dry
cooling tower. Dry cooling is the newer technology. Dry cooling is more efficient,
reduces air emissions, uses less water, and lowers the temperature of water discharges
more effectively. Many existing facilities are replacing wet cooling towers with dry
cooling towers. Dry cooling towers are also smaller in size and do not produce as much
noise as wet cooling towers. Although, once through cooling towers is the preferred
technology in coastal areas.
Source: U.S. Department of Energy.
Effects Of Thermal Pollution
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Warmer temperatures lower dissolved oxygen content by decreasing the solubility of
oxygen in water. Temperature often determines the kind of microorganism that exists in
an aquatic environment. Warmer water also causes aquatic organisms to increase their
respiration rates and consume oxygen faster, and it increases their susceptibility to
disease, parasites, and toxic chemicals. Discharge of heated water into shallow water near
the shore of a lake also may disrupt spawning and kill young fish. This will upset balance
in the whole system.
Because of complexity of natural systems, it is misleading to generalize on temperature
effects on aquatic biota. More proper is to study locally important species. Temperature is
important to maintenance of optimum characteristics in water based ecological systems.
Fish and other organisms adapted to a particular temperature range can also be killed
from thermal shock, which is the effect of sharp changes in water temperature when new
power plants open up or when plants shut down for repair. One example is temperatures,
which do not kill fish, or shellfish may produce effects in metabolism, reproduction and
growth as well as reducing certain food organisms.
Many fish also die on intake screens used to prevent fish from clogging the heat
exchanger-pipes. This issue is rapidly becoming a hotly contested debate and has led to
new legislation that will be explored in another section of the paper.
Many reactions effecting water quality are biochemical and center around microbial
activity. Most reactions occur at low temperatures in presence of enzymes, which in turn
are temperature sensitive. Most are in the mesophylic classification and thrive on
temperature range of 10 to 40ºC.Maximum activity occurs between 30 and 37ºC and then
falls off.
Environmental engineers and chemical engineers take a narrow view of thermal
pollution, unfortunately. Their jobs are to remove heat from waste streams so that
discharge regulations are satisfied. The regulation may be stated as the volumes and
temperatures that are permissible for discharge or as the thermal rise that is that is
tolerable for the receiving water. In a broader sense, and with the concern about global
warming, engineers do little to mitigate the effects on earth because they take air or cool
water from the environment to exchange heat with their waste streams.
REGULATIONS AND POLICY ISSUES
Summary
As the nations population increases, so does the need for increased electricity and
drinking water supplies from surface waters and groundwater. Coastal populations are
overwhelmingly increasing as more and more people seek the comforts coastal
communities bring to everyday life. Electricity producing power plant sites are a priority
in meeting the nations needs for these resources. More and more states are looking at
coastal sites for power plants as the search for diminishing water supplies intensifies.
Proposed and existing facilities must meet and be in compliance with federal, state, and
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local siting criteria. The best technologies available must be used when planning such
facilities. Thermal discharges must be at a level that would assure protection and
propagation of a balanced indigenous population of fish, shellfish and wildlife.
For instance, in California and most other states, new facilities must apply for a National
Pollution Discharge Elimination System (NPDES) permit through the State Water
Resources Control Board (SWRCB), which applies to water discharge requirements. A
proposed facility must also meet state coastal zone management thermal plan legislation
as set forth by such state programs (i.e. California Coastal Commission), which deal with
biological and human health issues that are scientifically based in the Coastal Act. The
regulations at this level are usually different interpretations relating to water quality
issues. Approval must be obtained from these kinds of authorities. Coastal zone
management programs are federally approved. Finally, the facility must be in compliance
to the federal Clean Water Act and its guidelines addressing thermal discharges into a
body of water section 301(a) and 310(b). The effluent discharged must be within 20
degrees F of the existing water body temperature (receiving water) and use the best
available technology for minimizing adverse environmental impacts.
Individual states do have the authority to implement even more stringent regulations but
cannot approve a project that does not meet federal requirements. This section will focus
on some of the existing policies.
Background
In the United States, the serious campaign against water pollution began in 1972, when
Congress passed the Clean Water Act. The Clean Water Act defines pollutant very
broadly encompassing ant type of industrial, municipal, and agricultural waste discharged
into U.S. waters, including heat. This law initiated a national goal to end all pollution
discharges into surface waters, such as lakes, rivers, streams, wetlands, and coastal
waters.
The law required those who discharge pollutants into waterways to apply for federal
permits and to be responsible for reducing the amount of pollution over time. The law
also authorized generous federal grants to help states build water treatment plants that
remove pollutants, principally sewage, from wastewater before it is discharged. The EPA
sets standards, approves state control plans, and steps in when necessary if state programs
are failing to enforce its own rules.
The EPA has equivalents in many countries, although details of responsibilities vary. For
instance, the federal governments may have a larger role in pollution control, as in
France, or more of this responsibility may be shifted to the state and provincial
governments, as in Canada. Because many rivers, lakes, and ocean shorelines are shared
by several nations, many international treaties also address water pollution. For example,
the governments of Canada and the United States have negotiated at least nine treaties or
agreements, starting with the Canada-U.S. Boundary Waters Treaty of 1909, governing
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water pollution of the many rivers and lakes that flow along or across their common
border.
The oceans, as vast as they are, are not invulnerable to pollution. Several major treaties
deal with oceanic pollution, including the 1972 Convention on the Prevention of Marine
Pollution by Dumping of Wastes and Other Matter and the 1973 International Convention
for the Prevention of Pollution from Ships (known as MARPOL). International controls
and enforcement, however, are generally weak.
NPDES Permitting
Pollution may reach natural waters at spots we can easily identify, known as point
sources, such as waste pipes, ditch, channel, or mine shafts. The Clean Water Act
prohibits the discharge of pollutants through a known point source into existing U.S.
waters unless they have an NPDES permit (US EPA, 1999). The permit will contain
limits on what can be discharged, monitoring and reporting requirements, and other
provisions to ensure that the discharge does not seriously degrade water quality or
people’s health. The permit translates general requirements of the Clean Water Act into
specific provisions designed to meet the operations of each discharged pollutant (US
EPA, 1999).
NPDES permits are issued by states that have obtained EPA approval to issue such
permits or by EPA Regions in states without such approval (US EPA, 1999). The permit
requires the facility to sample its discharges and notify EPA and the state regulatory
agency when the facility determines it is not in compliance with the requirements of the
permit. EPA and state regulatory agencies also periodically send inspectors to ensure
compliance with permits. Injunctions or penalties, such as fines, can be administered if a
facility is deemed in violation of the issued permit requirements. The Clean Water Act
limits the length of NPDES permits to five years but they can be renewed at any time (US
EPA, 1999).
On a side note, non-point sources are more difficult to recognize. Pollutants from these
sources may appear a little at a time from large areas, carried along by rainfall or
snowmelt. For instance, the small oil leaks from automobiles that produce discolored
spots on the asphalt of parking lots become non-point sources of water pollution when
rain carries the oil into local waters. Most agricultural pollution is non-point since it
typically originates from many fields.
Coastal Power
Coastal power plants use ocean water in once through cooling system designs. The
plants intake ocean water through cooling water intake structures and use this water for
heat exchanges between the water and their equipment and then discharge this water
directly along the shore. Most current regulations require discharges to be a significant
distance from the shore depending on the biological aspects of the immediate aquatic
species in the coastal zone. The discharge pipes lie on the seafloor and can extend 1000
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feet or more. The use of ocean water for cooling such structures is given a high priority
by regulatory agencies as opposed to fresh water sources. In other words, it is the
preferred method and strongly encouraged when new sites for facilities are being
proposed even though the dry cooling and hybrids between the wet cooling and dry
cooling methods are more efficient and use smaller amounts of sea water.
The modernization or re-powering of existing power supply plants is gaining widespread
acceptance in the industry. This involves the reuse of existing discharge and intake
facilities at an existing power plant site while replacing the power generating facility. Repowering of these projects may result in the regional water quality control board treating
the thermal discharge as a new discharge, and usually require the reevaluation of federal
and state permit conditions. Typically, establishment of a comprehensive database on the
existing biological resources potentially being impacted is required for any proposal to
re-power or modernize. For example, in California, the California Coastal Commission in
its Coastal Act and the SWRCB policies give preference to and top priority in using
existing plants to increase energy output. By retrofitting the plant and by not increasing
the intake and discharge flow a generator is able to use existing grand fathered NPDES
discharge permits. The procedure is subject to review by the proper authority on a caseby-case analysis of course. Generators are accelerating this procedure with the
apprehensive and almost reluctant support from regulatory agencies. In addition in
California, the SWRCB has adopted an Ocean Plan and a Thermal Plan, with which such
projects must comply.
The state of California is leading the crusade to find a solution to the immediate need to
increase energy supplies while not exhausting potable water sources and further
degradation of the coastal environment. Several state energy commissions are extremely
interested in addressing power plant water requirements and water supply issues
promptly so that water supply dos not create a constraint to permitting desperately needed
new plants. The main coastal issues related to such projects include flow reduction,
decreased discharge temperatures, and reduction in the size of towers all of which can be
improved upon leading to more efficient forms of energy production and better
environmental protection. This is a direct result of federal regulations imposed on new
facilities that are extremely difficult to comply with.
In the face of energy shortages, many states are scrambling to meet energy needs with
little help from the federal government. Federal regulations under 316(a) require new
discharges from power supplying facilities to meet a 20 degree F temperature difference
between the discharge and the receiving waters (US EPA, 1972). Ocean discharges are
also required to meet a 4 degree F difference between your discharge and the receiving
water at 1000 feet (US EPA, 1972 and 2002). Governing state, regional, or local water
authority agencies often implement the thermal regulations. The federal government has
chosen to delegate the authority to implement sections 316(a) and 316(b) down to
regional water boards similar to their stance towards the Clean Air Act (California
Energy Commission, 2001). These regulations are significant constraints on new
facilities. There are currently many claims from power generators that this particular
piece of legislature has no credible scientific studies proving the fact that particular
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species are threatened above this temperature level. Even though in the scientific
community it is common knowledge that some species, in particular microscopic
plankton, can be affected at a 1 degree F temperature increase.
An interesting issue about water quality standards for the discharge of heat is that the
federal Clean Water Act also includes a provision in section 316(a) that essentially says
the thermal standards can be waived as long as it can be shown scientifically that
population balance of fish, shellfish, and wildlife can be obtained (US EPA, 1972). That
is the balanced indigenous population of fish, shellfish, and wildlife can be supported in
the body of water where the discharge occurs. Exceptions to the legislation must undergo
close scrutiny by regulatory agencies and be backed by strong long-term scientific
evidence.
Developers of coastal facilities must present an accurate profile of the proposed discharge
waters. Short-term studies in the range of 30 to 90 days are required to determine water
temperatures. Mathematical models of the thermal plume of water and what the predicted
biological effects might be of that discharge based on historical knowledge is also
considered with a particular thermal discharge. Extensive short-term studies can help
establish baselines that can be confirmed in a relatively short period of time but long-tern
studies would solidify accurate environmental scenarios. Suggested long-term studies of
a year or more need to be implemented in order to ensure accurate information before
expediting such important projects. Biologically sensitive areas such as estuaries need to
be avoided.
Best Available Technology (BAT)
Legislation calls for the Best Available Technology (BAT) to be used in designing or
modernizing existing thermal emitting facilities. This particular legislation when
applicable has significantly improved coastal environments from the effects of thermal
discharges. Advanced technologies can reduce discharge temperatures, decrease water
usage, lower air emissions, and improve energy producing efficiencies. BAT involves
technology based standards established by the Clean Water Act as the most appropriate
means available on a national basis for controlling the direct discharge of toxic and nonconventional pollutants to navigable waters. BAT effluent limitations guidelines, in
general, represent the best existing performance of treatment technologies that are
economically achievable within an industrial point source category or subcategory.
Cooling Water Intake Structures
Section 316(b) of the Clean Water Act requires the EPA to ensure that the location,
design, construction, and capacity of cooling water intake structures reflect the best
technology available for minimizing adverse environmental effects (US EPA, 200). The
EPA has developed national standards in three phases: Phase I for new facilities, Phase II
for existing electric generating plants that use large amounts of cooling water, and Phase
III for electric generating plants using smaller amounts of cooling water and for
manufacturers. The Phase I rule applies to new electric generating plants and
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manufacturers that withdraw more than two million gallons per day (MGD) from waters
of the U.S., if they use 25% or more of their intake water for cooling. New facilities with
smaller cooling water intakes will still be regulated on a site-by-site basis (US EPA,
2001).
For facilities that choose certainty and fast permitting over greater flexibility, the
rule sets standards to limit intake capacity and velocity. Facilities who locate
where fisheries need additional protection must use special screens, nets or similar
devices. Facilities withdrawing less than 10 MGD are not required to reduce
intake capacity, but must use special screens, nets or similar devices if they do
not. For facilities that choose to perform site-specific studies, the rule sets a
framework for demonstrating that alternative approaches provide comparable
protection. All facilities must limit their withdrawals to no more than a defined
proportion of their source water body.
The EPA Administrator approved this proposed environmental regulation on February
28, 2002. The regulation is designed to protect fish, shellfish, and other aquatic life from
being killed or injured by cooling water intake structures. The rule remains flexible and
would not close any existing electric generating facilities adversely affecting energy
supply, distribution or use. Strong technology based performance standards would apply
unless a facility shows that these standards would result in very high costs or littler
environmental benefit at their site. Facilities could choose to demonstrate to permitting
authorities that protecting wetlands or restoring degraded aquatic habitat would result in
comparable environmental performance within a water body as meeting technology
requirements.
With EPA approval, states could set alternative requirements for facilities that achieve
comparable environmental performance within a watershed. The new legislation is a step
forward in protecting coastal resources and requiring power generators to accept some
responsibility in providing environmentally safe energy to consumers by using the most
advanced technology economically feasible so that electricity prices do not skyrocket.
This is where the flexibility has to be weighed by regulatory agencies. Affordable energy
prices without harming biological resources and human health is the ultimately the
overall goal of all participants.
Case Studies
Not all thermal discharges are from power generating facilities. The South Island Public
Service District located on Hilton Head Island, South Carolina drilled into the Cretacious
aquifer below the Upper Floridian some 3600 feet in search of a new source of drinking
water. The temperature of the water drawn from this aquifer exceeds 140 degrees F. The
new source of potable water is now part of a reverse osmosis plant that supplies drinking
water to a rather modest population except during the summer months when the resort
island is at full capacity population wise. The reverse osmosis treatment of drinking water
does produce a wastewater by-product that can be high in temperature and salinity. The
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wastewater from this process is piped underground through a forest preserve and into the
Calibogue Sound where it meets somewhat sub-tropic Atlantic Ocean water. The
temperature in the area of the sound where the discharge is applied has increased slightly.
Interestingly, the service district and the state choose this location that has already been
rendered extremely polluted by the state due to a rather large and exotic marina called
Harbourtown even though abundant recreational activities are common in the sound.
Groundwater drinking water supplies the island during the winter months when demand
is low. Vacationers flocking to the island during the summer months increase demand so
the reverse osmosis is then operating at full capacity because the wastewater generated
from this process can meet federal thermal discharge requirements in the warmer Atlantic
waters during the summer months. The shellfish and shrimp in the sound have no chance
of recovering from the increasing activities.
There is currently a Duke Energy power plant on the Central Coast of California in the
city of Morro Bay that is undergoing a re-power project. Morro Bay has a protected
estuarine ecosystem in place called the Estero Bay. Located south of the bay is the
nuclear energy plant Diablo Canyon. Both energy facilities discharge once through
cooling waters directly on-shore slightly altering the cold-water species indigenous to the
area to that of warm water species that you would find around San Diego.
The Morro Bay project is located in town very close to a public beach. It is a sore sight to
see while at the beach. It can also be extremely noisy. The cooling towers protrude close
to 200 feet. The cooling water is discharged near Morro Rock, a popular surfing spot, sea
kayaking, and sea otter habitat. Sea otters have a well-documented sensitive
environmental history in California.
Duke Energy proposed to modernize this plant to address some of the perceived harmful
characteristics of this plant. The cooling towers are to be replaced with smaller more
efficient hybrid wet/dry cooling towers. The noise will be reduced significantly, the use
of cooling water will decrease therefore reducing the amount of discharged heated water
into the bay, the new towers will emit less air pollution, and the profile of the plant will
be smaller in size. The project is really an entire replacement of the electricity producing
facility while attempting to remain using the existing intake and discharge units so a new
NPDES permit will not have to be applied for. As mentioned before, the new regulations
are extremely difficult to comply with. The project is a direct result of an increase in
demand for power in the rapidly developing area. The project has been approved even
though environmental groups are not happy that a thermal plume is discharged so close to
the shore. The same shore that has been recently designated a bird sanctuary for the
endangered Snowy Plover. The bottom line in the approval process was that the public’s
benefit and coastal access near this area has not been adversely affected.
South of Estero Bay is Diablo Canyon nuclear power facility. The area surrounding the
facility is off limits due to security reasons. The nuclear facility intakes water directly
from the shore and discharges thermal water along the shore. The amount of thermal
discharge is significant enough to have altered the coastal ecosystem to a warm water
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habitat. The plant would not meet the new EPA regulatory criteria concerning thermal
discharges into the ocean. The PG&E facility has no public coastal benefits except the
production of a significant amount of electricity for San Luis Obispo County.
Immediately north of the facility is Montano de Oro, a state park that has been supported
by the power generator. The recreational area is considered more of a buffer zone
between the facility and local communities. So some public benefit has been associated
with the reasoning behind such a facility.
Another example of the exception to the thermal discharge limitations demonstrating that
the existing limitations are more stringent than necessary to protect and maintain
balanced indigenous communities in the affected water body, taking into consideration
the interaction of such thermal components with other pollutants is the San Onofre
Nuclear Generating Station (SONGS) (CA SWRCB, 1999). SONGS employs one
through cooling water systems, withdrawing cooling water from the Pacific Ocean and
discharging it to the ocean through separate underwater diffusers situated on the ocean
bottom approximately one-half to one and one-half miles offshore (CA SWRCB, 1999).
The diffusers are placed such that sensitive near shore marine habitat, especially intertidal and shallow sub-tidal habitat, will not be affected by heat from the discharge. The
generators produced extensive scientific research to the California SWRCB in order to
increase power production through the retrofitting of existing structures within the plant.
The state of Oregon has also been active in thermal discharge issues. The problem they
face is with inland streams. Approximately 700 Oregon streams are impacted by the
excedance of temperature standards than by any other water quality parameter (USGS,
1999). Watershed authorities have acknowledged this may be the most difficult problem
they encounter when addressing water quality issues. The problem may require
extraordinary efforts to achieve temperature standards. The Oregon thermal pollution
situation is considered a non-point source pollution problem because of the many sources
of heat-loading sources. They are experimenting with an innovative approach with the
possibility of effluent credit trading serving as an incentive for non-point sources as an
aggressive effort to mitigate the pollution (USGS, 1999). Effluent credit trading identifies
the often difficult to identify non-point pollution sources. A tracking record would then
be implemented regulating such sources.
SOLUTIONS FOR REDUCING THERMAL POLLUTION
There are a number of ways to minimize the harmful effects of excess heat on aquatic
ecosystems as indicated by the following suggestions.
Prevention
Using and wasting less electricity can help and make a difference. In coastal areas, this
means less strain on existing power suppliers and therefore a reduction in the intake of
water to cool existing electricity producing mechanical machinery. Limiting the amount
of heated water discharged into the same body of water is the most obvious choice.
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Control by Dilution
Returning the heated water at a point away from the ecologically vulnerable shore zone.
Extensive research in determining the point at which no adverse biological effects on the
ecosystem will have to be employed in order for this to be successful. Also, more
efficient transferring of the heat from the water to the atmosphere by means of wet or dry
cooling towers lowers discharge temperatures accordingly.
Discharging the heated water into shallow ponds or canals, allowing it to cool, and
reusing it as cooling water can lower water use. This method is useful where enough
affordable land is available for application.
Another solution is the desalinization of seawater. The water vapor exchanges heat with
colder cooling water, thus condensing to form distilled water. From this process we can
use up more of the would be waste heat and get drinking water at the same time.
We could live more efficient lives. This includes the last three solutions on the list. We
could turn to wind power, hydroelectric power, solar power, or hydrogen fuel cells in
order to use less nuclear power, which would in turn expend less excess heat. We could
restrict the removal of trees that protect the shoreline from the suns warming rays. We
could even use the already known methods for preventing soil erosion. Things such as
plowing fields in a circular motion, disking fields instead of plowing them, and using
ground cover species where possible.
Thermal pollution truly is a global problem. It's ignorant to assume that the warming of a
river is a local problem, that the oceans are so vast we can't alter their temperature, that
we can continue abusing our environment as we have in the past. The rivers flow into the
interconnected seas. The atmosphere's temperature has been changed directly by humans.
If we continue in our denial of the destructiveness of our actions, we will kill not only
ourselves but also every species on the planet and destroy all chances for re-growth. This
may sound like a harsh stance to take but nonetheless it is the reality of the overall picture
that not only our generation but future generations may have to come to terms with.
Potential Benefits
While some scientists call the addition of excess heat to aquatic systems thermal
pollution, others talk about using heated water for beneficial purposes, calling it thermal
enrichment. Warm water from power plants can also be used for irrigation to extend the
growing season in frost-prone areas and cycled through aquaculture pens to speed the
growth of commercially valuable fish and shellfish. For example, waste hot water is used
to cultivate oysters in aquaculture lagoons in Japan and in New York's Long Island
Sound and to cultivate catfish and redfish in Texas.
Heated water could also be used to heat nearby buildings and greenhouses, desalinate
ocean water, and run under sidewalks to melt snow. However, because of dangers from
air pollution and release of radioactivity, most coal-burning and nuclear electric power
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plants and heat-producing factories are usually not located near to aquaculture operations,
buildings, and industries to make thermal enrichment economically feasible
It should also be pointed out that heated water results in longer commercial fishing
seasons and reduction of winter ice cover in cold areas.
Other Notable Facts
On national scale, industrial once through cooling waters is a first-order source of heat.
Electro power generation uses 80% of cooling waters see Table 1.
Table 1. The use of cooling water by various U.S. industries as determined by the U.S.
Department of Energy.
Cooling Water
(Billions of
M3)
(%)
Electric Power
153.7
81.23
Primary Metals
12.8
6.76
Chemical and Allied
Products
11.8
6.24
Petroleum and Coal
Products
4.6
2.43
Paper and Allied
Products
2.30
1.21
1.48
0.78
0.620
0.34
Rubber and Plastics
0.484
0.26
Transportation
0.386
0.21
All Other
1.03
0.54
Totals
189.2
100.0
Food
Machinery
Source: U.S. Department of Energy.
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The best single index of thermal pollution lies in projecting future electric power
generation, which will no doubtlessly increase as populations increase the demand for
more energy and electricity. Past experience has indicated that thermal pollution has not
multiplied as fast as power generation because of improvements in thermal plant
efficiency and development of hydropower. A reoccurring problem is one of managing
tremendous amounts of waste heat in a manner that will maintain or enhance, physical,
chemical and biological nature of our water resources.
Approximately one-half of all water used in U.S. is used for cooling by power and
manufacturing industries (Davidson, and others, 2002). During the past half-century
power generation has virtually doubled every 10 years (Davidson, and others, 2002). This
trend is expected to continue or perhaps increase.
Power generation has been either for hydropower or steam-electric. The latter requires
cooling water. Remaining sites for hydropower are limited. Thermal plants continue to
gain a larger portion of the market for power.
Nuclear power plants waste even a higher proportion of generated heat than fossil fuel
fired plants. Nuclear plants presently do not exceed 33% (metal strength) (Davidson, and
others, 2002). The best and most efficient fossil-fuel plants only operate at about 40%
(considered to be about limit) (Davidson, and others, 2002).
Conclusions
Supplying affordable electricity to growing populations without sacrificing existing
environmental regulations is a formidable challenge indeed. The demand for energy has
even caused blackouts in California where the demand is greater than the supply during
certain periods. Coastal populations are increasing at an alarming rate demanding more
energy and drinking water supplies.
Although at first, the two demands may seem to be very different and separate entities. A
closer evaluation of the two ties them together intrinsically. Electric generating facilities
are currently designed to use a large amount of water for heat exchange of cooling the
equipment necessary for generating power to the people. The heated water therefore
needs to be cooled before being discharged to avoid biological damage to aquatic species.
What better body of water to discharge into than the ever-expanding ocean? Federal,
state, and local regulatory agencies have stepped in to ensure that the necessary rules are
in place to minimize the damages environmentally, economically, and medically to
humans and the ecosystem. A concerted effort by all regulatory agencies involved is the
necessary solution to mitigate the existing problem.
The overall analysis of the legislation in place and the performance of the regulatory
authorities in place have been adequate. The focus is currently shifting to improving the
efficiency of existing facilities by modernizing these plants with the best available
technologies that are cost effective and environmentally sound. New facilities that will
include thermal discharges must provide long-term data using historical temperature
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baselines and ecological assessments of the immediate area to be affected by the
discharged thermal plume. Finally, the heat generated during this process could be used
in beneficial ways to minimize the waste of a perfectly good energy source through
unique local heating techniques.
REFERENCES
California Energy Commission. Comparison of Alternative Cooling Technologies.
California Power Plants: Economic, Environmental and other Tradeoffs. Publication
Number: not yet assigned (600-02-XXX). Publication Date: July, 2002.
California Energy Commission. Timing of Federal Permit Constraints. California
Environmental Office. Water Supply Paper. Publication Date: January, 2001.
California State Water Resources Control Board. San Onofre Thermal Plan Exception
Approval. Resolution No. 99-028. April, 1999.
Davison, D. and others. Thermal Pollution: A Global Problem. Academic Global
Thermal Pollution Conference, October 2002.
US EPA. Office of Water. Clean Water Act section 316. United States Environmental
Protection Agency. 1972 and Amendments 2002.
US EPA. Office of Water 4303T. Fact Sheet: Cooling Water Intake Structures at Large
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US EPA. Office of Water. Criteria and Standards for the National Discharge Elimination
System. United States Environmental Protection Agency. Code of Federal Regulations.
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USGS. Water Resources Research Grant Proposal. Mitigation of High Stream
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