Recently, attention also has been given to other substances, such as volatile organic compounds VOCs , chlorides, ozone, and trace metals that may participate in a complex set of chemical transformations in the atmosphere, resulting in acid precipitation and the formation of other regional air pollutants.
It is well known that some energy-related activities are the major sources of acid precipitation. Additionally, VOCs are generated by a variety of sources and comprise a large number of diverse compounds.
Obviously, the more energy we expend, the more we contribute to acid precipitation; therefore, the easiest way to reduce acid precipitation is by reducing energy consumption. A global environmental problem is the depletion of the stratospheric ozone layer, which is caused by the emissions of chlorofluorocarbons CFCs , halons chlorinated and brominated organic compounds , and NOx. Ozone depletion can lead to increased levels of damaging UV radiation reaching the ground, causing increased rates of skin cancer and eye damage to humans, and is harmful to many biological species.
It should be noted that energy-related activities are only partially directly or indirectly responsible for the emissions that lead to stratospheric ozone depletion. The most significant role in ozone depletion is played by the CFCs, which are mainly used in air-conditioning and refrigerating equipment as refrigerants, and NOx emissions, which are produced by the fossil fuel and biomass combustion processes, natural denitrification, and nitrogen fertilizers.
Full recovery is predicted to occur in ; however, the rate of recovery is affected by the climate change Dincer, The term greenhouse effect has generally been used for the role of the whole atmosphere mainly water vapor and clouds in keeping the surface of the earth warm. Additionally, several other gases, such as CH4, CFCs, halons, N2O, ozone, and peroxyacetylnitrate also called GHGs , produced by the industrial and domestic activities can contribute to this effect, resulting in a rise of the earth's temperature.
Increasing atmospheric concentrations of GHGs increase the amount of heat trapped or decrease the heat radiated from the earth's surface , thereby raising the surface temperature of the earth. According to Colonbo , the earth's surface temperature has increased by about 0.
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These changes can have a wide range of effects on human activities all over the world. According to the EU, climate change is happening. There is an overwhelming consensus among the world's leading climate scientists that global warming is being caused mainly by carbon dioxide and other GHGs emitted by human activities, chiefly the combustion of fossil fuels and deforestation.
An ice core is a core sample from the accumulation of snow and ice over many years that has recrystallized and trapped air bubbles from previous time periods. The composition of these ice cores, especially the presence of hydrogen and oxygen isotopes, provides a picture of the climate at the time. The data extracted from this ice core provide a continuous record of temperature and atmospheric composition. Two parameters of interest are the concentration of CO2 in the atmosphere and the temperature.
If one considers, however, the present December CO2 level, which is Humans, through many of their economic and other activities, contribute to the increase of the atmospheric concentrations of various GHGs. For example, CO2 releases from fossil fuel combustion, methane emissions from increased human activities, and CFC releases contribute to the greenhouse effect. The impacts of such sea level increase can easily be understood and include flooding of coastal settlements, displacement of fertile zones for agriculture to higher latitudes, and decrease in availability of freshwater for irrigation and other essential uses.
Thus, such consequences could put in danger the survival of entire populations. Nuclear energy, although non-polluting, presents a number of potential hazards during the production stage and mainly for the disposal of radioactive waste. Nuclear power environmental effects include the effects on air, water, ground, and the biosphere people, plants, and animals. Nowadays, in many countries, laws govern any radioactive releases from nuclear power plants. In this section some of the most serious environmental problems associated with electricity produced from nuclear energy are described.
These include only the effects related to nuclear energy and not the emissions of other substances due to the normal thermodynamic cycle. The first item to consider is radioactive gases that may be removed from the systems supporting the reactor cooling system.
The removed gases are compressed and stored. The gases are periodically sampled and can be released only when the radioactivity is less than an acceptable level, according to certain standards. Releases of this nature are done very infrequently. Usually, all potential paths where radioactive materials could be released to the environment are monitored by radiation monitors Virtual Nuclear Tourist, Nuclear plant liquid releases are slightly radioactive. Very low levels of leakage may be allowed from the reactor cooling system to the secondary cooling system of the steam generator.
However, in any case where radioactive water may be released to the environment, it must be stored and radioactivity levels reduced, through ion exchange processes, to levels below those allowed by the regulations. Within the nuclear plant, a number of systems may contain radioactive fluids.
Those liquids must be stored, cleaned, sampled, and verified to be below acceptable levels before release. As in the gaseous release case, radiation detectors monitor release paths and isolate them close valves if radiation levels exceed a preset set point Virtual Nuclear Tourist, Nuclear-related mining effects are similar to those of other industries and include generation of tailings and water pollution.
Uranium milling plants process naturally radioactive materials. Radioactive airborne emissions and local land contamination were evidenced until stricter environmental rules aided in forcing cleanup of these sites. As with other industries, operations at nuclear plants result in waste; some of it, however, is radioactive. Solid radioactive materials leave the plant by only two paths:. These drums must be thoroughly dewatered. The drums are often checked at the receiving location by regulatory agencies.
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Special landfills must be used. LLW is shipped from nuclear plants and includes such solid waste as contaminated clothing, exhausted resins, or other materials that cannot be reused or recycled. Most anti-contamination clothing is washed and reused; however, eventually, as with regular clothing, it wears out. In some cases, incineration or super-compaction may be used to reduce the amount of waste that has to be stored in the special landfills. HLW is considered to include the fuel assemblies, rods, and waste separated from the spent fuel after removal from the reactor.
Currently the spent fuel is stored at the nuclear power plant sites in storage pools or in large metal casks. To ship the spent fuel, special transport casks have been developed and tested.
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Originally, the intent had been that the spent fuel would be reprocessed. The limited amount of highly radioactive waste also called HLW was to be placed in glass rods surrounded by metal with low long-term corrosion or degradation properties. Various underground locations can be used for this purpose, such as salt domes, granite formations, and basalt formations. The objective is to have a geologically stable location with minimal chance for groundwater intrusion.
The intent had been to recover the plutonium and unused uranium fuel and then reuse it in either breeder or thermal reactors as mixed oxide fuel. Renewable energy technologies produce marketable energy by converting natural phenomena into useful forms of energy. These technologies use the sun's energy and its direct and indirect effects on the earth solar radiation, wind, falling water, and various plants; i.
These resources have massive energy potential; however, they are generally diffused and not fully accessible, and most of them are intermittent and have distinct regional variabilities. These characteristics give rise to difficult, but solvable, technical and economical challenges.
Nowadays, significant progress is made by improving the collection and conversion efficiencies, lowering the initial and maintenance costs, and increasing the reliability and applicability of renewable energy systems.
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Worldwide research and development in the field of renewable energy resources and systems has been carried out during the past two decades. Energy conversion systems that are based on renewable energy technologies appeared to be cost-effective compared with the projected high cost of oil. Furthermore, renewable energy systems can have a beneficial impact on the environmental, economic, and political issues of the world. The benefits arising from the installation and operation of renewable energy systems can be distinguished into three categories: energy saving, generation of new working posts, and decrease in environmental pollution.
This action might not be possible to undo. Are you sure you want to continue? Upload Sign In Join. Home Books Science. Save For Later. Create a List. Summary Energy policy promoting sustainable development is transforming global energy markets. Read on the Scribd mobile app Download the free Scribd mobile app to read anytime, anywhere.
Introduction 1. General introduction to renewable energy technologies 1. Energy demand and renewable energy 1. Energy-related environmental problems 1. State of the climate 1. A brief history of solar energy 1.
Other renewable energy systems Exercise Chapter 2. Environmental Characteristics 2. Reckoning of time 2.
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Solar angles 2. The solar resource Exercises Chapter 3. Solar Energy Collectors 3.