Introduction:
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Figure 1. Simplified Thermal Pollution(1) |
Thermal Pollution:
Merriam Webster dictionary defines thermal pollution as, "the discharge of heated liquid (as wastewater from a factory) into natural waters at a temperature harmful to the environment". The environment is referring to various groups including humans, animals, and aquatic life.
The blog is mostly going to discuss the fundamental issues occurring as a result of thermal pollution caused by nuclear power plants. In the picture stated above, Figure 1, we present a simple explanation of how nuclear power plants work and the negative byproducts they give off. Nuclear power plants use water as a cooling agent. After the water is used, it is recycled back into the ocean at 9-20 degrees Celsius warmer than its original intake temperature. In addition to warmer water put directly back to the water supply, emissions from the nuclear plant cooling tower also increase the temperature of the ambient water bodies.
The blog is mostly going to discuss the fundamental issues occurring as a result of thermal pollution caused by nuclear power plants. In the picture stated above, Figure 1, we present a simple explanation of how nuclear power plants work and the negative byproducts they give off. Nuclear power plants use water as a cooling agent. After the water is used, it is recycled back into the ocean at 9-20 degrees Celsius warmer than its original intake temperature. In addition to warmer water put directly back to the water supply, emissions from the nuclear plant cooling tower also increase the temperature of the ambient water bodies.
Figure 2: ASTER Thermal Infrared Image of Power Plant Thermal Pollution in Illinois(3) |
“These ASTER false-color images were acquired over Joliet 29, a coal-burning power plant in Illinois. Joliet 29 can be seen in the VNIR image (top) as the bright blue-white pixels just above the large cooling pond. Like many power plants, Joliet 29 uses a cooling pond to discharge heated effluent water. In the bottom image a single ASTER Thermal Infrared band was color-coded to represent heat emitted from the surface. The progression from warmest to coolest is shown with the following colors: white, red, orange, yellow, green, blue, and black" (3) Through this thermal imager, the problem of warm water is not a phenomena, but an actual problem. The water is considerably hotter as can be seen from the infrared image. The redish portion of the picture displays that the water is much hotter than it is taken in. This results in a serious problem to the aquatic life around the area where the heated-up water is dumped in.
History:
Since the 1950’s nuclear power plants became the idle source of power for large populated areas. Southern California coasts began experiencing the building of nuclear power plants during the mid 1950’s. The first nuclear power plant created in Southern California was the Santa Suzanna power plant, it was active from the years of 1957-1964. (18) The power plant in the few years it was operating immediately had a nuclear meltdown. (18) This brought to attention the dangers of nuclear power plants, however the building of these refineries continued. The Humboldt Bay Power Plant utilized changes that would prevent meltdowns from occurring and was operating during the years of 1963-1976. (18) The plant was confined to be closed down for restructuring, and flaws were found prolonging the closure until this day. The problems which arose from such failures originally were not looked into depth as a result of lack in technological advances (4). Thermal pollution resulting from coastal power plants was originally studied by P.R.O Barnet in the early 70’s looking at the effects of power plants on the sand collected around the refineries. He realized that their was a loss in life amongst all the power plants he observed in various different parts of Scotland especially in Ayrshire, Scotland. (4)
Thermal pollution has been a controversial issue that has been improving according to legislature on one hand and becoming increasingly harmful based off of environmental group studies. The issue has been improving through the legislature passed to have cleaner nuclear power plants, however this does not mean there has been dramatic improvements. The main bill passed to combat thermal pollution as well as potential meltdowns are the Clean Water Act Section 1316 and the Nuclear Safety, Research, Demonstration, and Development Act of 1980. (14) The Clean Water Act Section 1316 in title B ensures that nuclear power plants using water for cooling need to have, "best technology available for minimizing adverse environmental impact". (13) This is a statement that the legislature argues forth, that costs are not a factor rather safety is. This was enacted in October 18, 1972. (13) In order to have another buffer zone, the government also enacted the Nuclear Safety, Research, Demonstration, and Development Act of 1980 stating that nuclear power plants had to display, “safety and efficiency” in a five year period before they were used on a large scale. (14) Although such strong measures are emplaced, activist groups are still fighting to stop the use of nuclear power. The Atomic Energy Commission now replaced by the Nuclear Regulatory Commission have been sued countless times as a result of the safety and environmental risks imposed by these structures. (15) The most recent lawsuit that affected the California nuclear power plants was, Friends of Earth vs. Nuclear Safety Research.(16) Friends of Earth argued the devastating effects on the local aquatic life as well as how it would eventually have serious problems as a result of the fault lines surrounding the nuclear power plant. (16)
Thermal pollution has been a controversial issue that has been improving according to legislature on one hand and becoming increasingly harmful based off of environmental group studies. The issue has been improving through the legislature passed to have cleaner nuclear power plants, however this does not mean there has been dramatic improvements. The main bill passed to combat thermal pollution as well as potential meltdowns are the Clean Water Act Section 1316 and the Nuclear Safety, Research, Demonstration, and Development Act of 1980. (14) The Clean Water Act Section 1316 in title B ensures that nuclear power plants using water for cooling need to have, "best technology available for minimizing adverse environmental impact". (13) This is a statement that the legislature argues forth, that costs are not a factor rather safety is. This was enacted in October 18, 1972. (13) In order to have another buffer zone, the government also enacted the Nuclear Safety, Research, Demonstration, and Development Act of 1980 stating that nuclear power plants had to display, “safety and efficiency” in a five year period before they were used on a large scale. (14) Although such strong measures are emplaced, activist groups are still fighting to stop the use of nuclear power. The Atomic Energy Commission now replaced by the Nuclear Regulatory Commission have been sued countless times as a result of the safety and environmental risks imposed by these structures. (15) The most recent lawsuit that affected the California nuclear power plants was, Friends of Earth vs. Nuclear Safety Research.(16) Friends of Earth argued the devastating effects on the local aquatic life as well as how it would eventually have serious problems as a result of the fault lines surrounding the nuclear power plant. (16)
Science behind:
Figure 3. Once-Through Cooling System (11) |
All the twelve power plants in the coastal area of Southern California use once-through cooling system to prevent reactors from meltdown. As found out by Natural Resources Defense Council, this “once-through cooling” technique is the most water-intensive method for thermoelectric power generation, and it also has the most harmful environmental and ecological impact.
The main mechanism of the power plant to utilize water is to withdrawn it from nearby water-bodies, flow it through the condenser, let water absorb enough heat to reach its boiling point, and use the hot water steam to spin the turbine and generate electricity. After flowing through the turbine, how water vapor cools down, condense to liquid water, yet still at high temperature, and flow back to the original water bodies.
There are two major ecological effects of the hot water that discharged back to the water bodies. First, after being heated up to boil, the dissolved oxygen in water drops dramatically, which means that there is much less oxygen for the marine creatures to breathe with. According to Moradian’s literature (5), the dissolved oxygen in water drops from 60 ppb (part per billion) to around 1 ppb when the temperature increases from 10 to 50 degree Celsius. This dissolved oxygen in water will approach closer to zero as the water temperature increases. With fewer oxygen in water, fish, and other aquatic creatures will be severely affected, and even suffocate to death. Additionally, the high-temperature discharged water can also “increase the metabolic rates of aquatic animals and cause them to consume more food than they normally do in unchanged environment”. (6) High consumption of food accelerate the depletion of producers in the food chain, which may lead to a major food shortage for all predators near the water bodies. A more direct impact of high-temperature water on human being is that at high temperatures, fish absorb more heavy metal ions, like mercury, than normally (7). The ingested mercury is stored inside the fish until humans ingest those heavy metal ions from their fish meal.
There are two major ecological effects of the hot water that discharged back to the water bodies. First, after being heated up to boil, the dissolved oxygen in water drops dramatically, which means that there is much less oxygen for the marine creatures to breathe with. According to Moradian’s literature (5), the dissolved oxygen in water drops from 60 ppb (part per billion) to around 1 ppb when the temperature increases from 10 to 50 degree Celsius. This dissolved oxygen in water will approach closer to zero as the water temperature increases. With fewer oxygen in water, fish, and other aquatic creatures will be severely affected, and even suffocate to death. Additionally, the high-temperature discharged water can also “increase the metabolic rates of aquatic animals and cause them to consume more food than they normally do in unchanged environment”. (6) High consumption of food accelerate the depletion of producers in the food chain, which may lead to a major food shortage for all predators near the water bodies. A more direct impact of high-temperature water on human being is that at high temperatures, fish absorb more heavy metal ions, like mercury, than normally (7). The ingested mercury is stored inside the fish until humans ingest those heavy metal ions from their fish meal.
Figure 4. Curve of Dissolved Oxygen against Water Temperature (5) |
Further, the once-through cooling system also affects environment negatively. Without recycling the cooling water, power plants in southern California withdraw around 14.5 billion gallons of seawater, which kills about six thousand fish and 4.7 million larvae, every day, which consisting about 8 to 30 percent of the normal fish caught in the Southern California Bight. (6)
Financially, the decrease in the amount of fish populations has a strenuous effect on the financial well being of individuals fishing these species. They are unable to effectively harvest the amount of fish needed to meet their quota, thus increasing the price of fish for the consumer, and leaving the producer ultimately to get out of business.
Figure 5. Impact of power plant on environment (6) |
In term of impact on human beings, due to the increase in temperatures, the fish in the surrounding waters start to have an increase in their rate of metabolism. The problem that occurs with this is that the fish tend to overeat and consume large amounts of mercury and other metals. In Pack’s study he found that at a high temperature, the inorganic mercury tend to react with a methyl group and form a MeHg complex, which is easier for fish to digest. In other words, in warmer water, fish would increase their absorption of mercury from what they eat, and those extra mercury ions would be absorbed by human beings in the end. The ingested mercury may cause damage to brains, kidneys, and lungs, and in some rare cases death occurs. (8)
There are 17 coastal Californian power plants using once-through cooling systems. These plants can withdraw more than 14 billion gallons per day from the Pacific Ocean. Nearly 5 billion gallons of that flow is withdrawn by two nuclear plants: the San Onofre Nuclear Generating Station near San Clemente and the Diablo Canyon plant near San Luis Obispo.
These power plants kill an astounding number of fish. The annual entrainment of larval fish at the Diablo Canyon plant at average flow is estimated to be over 1.5 billion individuals. At the San Onofre Nuclear Generating Station on the Southern California coast, 121 tons of midwater fish are entrained, causing a 34 to 70 percent decline in Pacific Ocean fish populations within about two miles (three kilometers). Unit 3 of the San Onofre plant alone is estimated to entrain an average of over 3.1 billion individual aquatic organisms.
The Pittsburg and Contra Costa plants in the San Francisco Bay Delta impinge and entrain more than 300,000 endangered and threatened fish per year, including the Sacramento splittail, Chinook, salmon and steelhead trout. The Contra Costa and Pittsburg power plants entrain and impinge threatened Delta smelt and endangered Longfin smelt. In addition to the entrainment of young life stages, Californian coastal plants impinge and kill huge numbers of older fish on their filter screens. At average flow rates, San Onofre’s Units 2 and 3 combined were estimated to impinge 1.3 million fish with a total weight of over 14 tons. This is the worst example on the California coast, but other plants also impinge significantly large numbers of fish. Units 6 and 7 at the Moss Landing plant were estimated to annually impinge a quarter of a million fish weighing 4,060 pounds, even though the plant’s average intake flow is a relatively modest 387 million gallons per day. In May 2010, California adopted a strong state policy requiring most coastal power plants to upgrade over the next decade to achieve protections equivalent to those offered by closed-cycle cooling. However, the dirty energy industry continues to fight these requirements. When contemplating the beauty of the Golden State, admirers invariably point to the breathtaking shoreline that has shaped California both culturally and historically. Power plants must help protect the beauty and economic vitality of the California Coast by using modern cooling system technologies. (9)
Possible Solutions:
The most practical solution for relieving the thermal pollution of power plants is utilizing the close-cycle cooling system instead of the once-through system of California. As introduced in NRDA’s article Power Plant Cooling and Associated Impacts: The need to Modernize U.S. Power Plants and Our Water Resources and Aquatic Ecosystems, the cooling water, after absorbing heat and raising in temperature, is drawn back to the cooling towers instead of discharging directly back to the original water bodies. This technique has been brought into operation by some power plants since early 1970s, and amount of water withdrawn from oceans has been reduced greatly. The aquatic impact of power plant’s thermal pollution has also been reduced by around 95 percent. Further, dry air was introduced as an alternate cooling agent other than water, yet it is much less efficient than water in hot regions and its overall cooling performance is still under hot debate. Another method is the Hybrid cooling system, which combines closed-cycle cooling and dry cooling systems together. The efficiency in hot areas is improved. Even though all these three systems are approved by EPA and the National Pollutant Discharge Elimination System (NPDES) Permit Program, the closed-cycle cooling system is still the most accessible and efficient industrial cooling method. (6)
Regulation:
The industrial thermal pollution was first addressed as an environmental-harmful issue in 1970 in the United States. Since then, the Congress entitled the Atomic Energy Commission authority to serve as a regulatory agency for the thermal pollution problem from Nuclear Power Plants. In two years, the Clean Water Act was published, which offered EPA a more comprehensive authority to regulate heat as a pollutant from all types of power plants. Regulation can be operated in various ways: laws can be established to set a specific limit for the temperature of discharged water, or alternate power plant designs are require in order to get the approval of building a power plant.(12)
Regulation:
The industrial thermal pollution was first addressed as an environmental-harmful issue in 1970 in the United States. Since then, the Congress entitled the Atomic Energy Commission authority to serve as a regulatory agency for the thermal pollution problem from Nuclear Power Plants. In two years, the Clean Water Act was published, which offered EPA a more comprehensive authority to regulate heat as a pollutant from all types of power plants. Regulation can be operated in various ways: laws can be established to set a specific limit for the temperature of discharged water, or alternate power plant designs are require in order to get the approval of building a power plant.(12)
Conclusion:
Up until now, most power plants are utilizing water vapor to spin the turbine thus generating electricity according to Faraday’s Law of Induction. Water plays an indispensable role in both converting thermal energy into electric energy and cooling down the reactor to keep the machines work properly. Water is still most most accessible and least expensive material to be utilized in the industry, so it may be hard and even impossible to find an substitution. Yet various operations can be conducted to relieve the effects of thermal pollution of power plants. The once-through cooling system can be replaced with closed-cycle cooling system, in which the cooling water is recycled and used to cool the condenser of the power plant. Additionally, dry air can also be used to replace water in the cooling tower, yet this dry cooling method is still in the research stage and quite controversial. (6)
Water
is used as a crucial fact or in cooling turbines. The problem with this is that
the waste product, warm water, gets deposited back into the ocean thus causing
damage. The overarching lesson to be learned from this dilemma is that an abundance
of a resource should not be exploited. Exploitation of resources that are
believed to be abundant has always resulted in negative consequences throughout
history. As we will demonstrate, the exploitation of natural resources
ultimately takes a toll on nature. Logging was once considered an abundant
resource with vast forests ranging throughout Wisconsin. In a thirty year
period from 1890-1920 with the new technological advances available forests in
Wisconsin were greatly reduced.(17) Not only were there less trees
to be cut down, the streams the logs were being sent downstream were also be
damaged according to the US Geological Survey. This problem was also apparent
in South America. From 1990 to 2005, Honduras experienced a decline of 37% of
its total forest cover. Over half of the entire country was covered by forests,
historically. Yet as the industries started to log desperately without proper
governmental regulation, only 16% of the country land remains a frontier forest
state. (10)
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13. Subsec. (c). Pub. L. 99–514substituted “Internal Revenue Code of 1986” for “Internal Revenue Code of 1954”, which for purposes of codification was translated as “title 26” thus requiring no change in text.
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12. Chinese Academy of Science and Chines Academy of Engineering. 2004. Urbanization, energy, and air pollution in China: the challenges ahead. National Research Council (U.S.) National Academy of Engineering. Page 296
13. Subsec. (c). Pub. L. 99–514substituted “Internal Revenue Code of 1986” for “Internal Revenue Code of 1954”, which for purposes of codification was translated as “title 26” thus requiring no change in text.
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18. "Nuclear Energy in California." - California Energy Commission. Web. 10 Mar. 2015. <http://www.energy.ca.gov/nuclear/california.html>.
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