Category Energy Systems Engineering

Management of Radioactive Substances During Life-Cycle of Nuclear Energy

Radioactive by-products that result from the nuclear energy process include both materials from the nuclear fuel cycle and equipment used in the transformation of nuclear energy that becomes contaminated through continued exposure to radioactive fuel, impurity elements, and cooling media. Although these waste products, especially high-level radioactive wastes, are moderately to very hazardous, they are also produced in volumes that are much smaller than other types of waste streams managed by society 6For comparison, the per capita energy consumption values in 2004 of France, Germany, and the U. K. are 209.2, 208.8, and 197.8 GJ/person, respectively.

(e. g., municipal solid waste, wastewater treatment plant effluent, and so on)...

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Life-Cycle Energy and Environmental Considerations

Along with economic return on investment, PV technology must achieve an adequate energy return on investment in order to qualify as a truly green technology. PV panels are made using a number of different processes under differing conditions, so there is no
one standard for measuring the energy input required per panel. Also, recouping the energy investment in embodied energy in the panel will depend on the location where it is installed, with sunny locations being more favorable than cloudy ones. Thus, there is not yet consensus on the value of PV energy return on investment or energy payback at this time. For conventional silicon technology, estimates vary, with numbers as low as 3 years and as high as 8 years reported...

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Using Statistical Distributions to Approximate Available Energy

The distribution of wind speeds in Table 12-1 provides a solid basis for calculating available energy at this site. However, suppose we only knew U = 5.57 m/s, and did not have the hourly bin data for the year. Observations have shown that in many locations, if the average wind speed is known, the probability of the wind speed being in a given range can be predicted using a statistical “Rayleigh” distribution.2 The prob­ability density function (PDF) for this distribution has the following form:

exp[-(x/a)[51]]

a2

Подпись: f (x) = 2x • Подпись: for x > 0 Подпись: (12-2a)

f (x) = 0, for x < 0

where a is a shape parameter for the Rayleigh function, and x is the independent vari­able for which the probability is to be evaluated. The cumulative distribution function (CDF) for the Rayleigh is then

Подпись: (12-2b)F(x) = 0, for x < 0

F(x) = 1 –...

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Biofuels: Transportation Energy from Biological Sources

Biofuels for transportation include any products derived from living organisms, ranging from food crops, to plant and tree material, to microorganisms, that can be processed into substitutes for liquid transportation fuels. The use of biofuels for transportation dates back to the early years of the ICE, when Rudolf Diesel, inventor of the diesel engine, used peanut oil as a fuel in his early engine prototypes. One of Diesel’s motivations was indeed to create a source of mechanical power that could burn a wide variety of fuels, so that small businesses of the day would not be captives of the coal industry for their energy supplies. In recent years, interest in biofuels has surged as nations such as Brazil and the United States have sought to reduce petroleum imports...

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Pathways to a Sustainable Energy Future: A Case Study

Following from the advantages of the portfolio approach, as discussed above, most projections of primary energy production for the twenty-first century recognize that the three endpoint technologies of Table 15-1 will all play a role in meeting demand, although the relative contribution of each resource varies from projection to projection. In this section we consider a possible scenario for transformation of energy production during the course of the century, along with some variations on the scenario to illustrate the range of possible outcomes.

In analyzing the scenario, we focus on nuclear and renewable energy resources as options that are relatively small now (each one less than 10% of total primary energy generation) but that might play a much larger role in the future...

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Prospects for Geological Sequestration

Sequestration research up to the present time indicates that between subterranean and sea-bottom options, there is adequate capacity for sequestration of all foreseeable CO2 emissions from fossil fuel production, provided that we invest sufficiently in facilities to separate and sequester it. The risk associated with sequestration, both from leakage under ordinary conditions and from seismic activity, is a more complex issue, and is considered in greater detail here.

Risk of leakage can be divided into acute leakage, where a hazardous amount of CO2 is released suddenly, and chronic leakage, where continuous low-level leakage leads to detrimental effects over the course of time...

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Definition of Solar Geometric Terms and Calculation of Sun’s Position by Time of Day

In the preceding section, we considered sunlight traveling through the atmosphere, without necessarily considering the effect of the sun’s position in the sky on the amount of energy available. In this section, we introduce several other terms used to discuss solar geometry, and then chart the sun’s position in the sky as a function of various parameters. Measures used in this section capture the effect of changing tilt of the earth relative to the sun, changing distance from the sun as a function of time of year and time of day, and the changing angular distance traveled by the sun, as a function of the same.

Solar angle calculations are done in solar time, which is defined by solar noon being when the sun is due south of the observer...

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Heat Transfer in Flat-Plate Solar Collectors

Useful thermal energy obtained from a solar collector is the difference between incident solar radiation transmitted through the glazing and absorbed as heat, and heat lost back to ambient conditions. The difference is the heat transferred to the working fluid. In a steady state, the governing equation, normalized to the absorber plate area, is

qx = (m)Aap – ULAap (tap – ta) = mcp (to – tt) (11-2)

where A = area of the absorber plate, m2

ap

cp = specific heat of the transport fluid, J kg-1 K-1 I = instantaneous direct normal solar irradiation, W m-2 m = transport fluid mass flow rate, kg s-1 qx = useful heat gained, W ta = ambient air temperature, °C

t. = temperature of the transport fluid flowing into the collector, °C

Heat Transfer in Flat-Plate Solar Collectors

Figure 11-10 Example efficiency graphs for single – and doub...

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