Energy Resources And Systems Volume 1 Fundamentals And Nonrenewable Resources Pdf
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- Volumes | Energy Sustainability | American Society of
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- Can the World Run on Renewable Energy?
Conventional energy source based on coal, gas, and oil are very much helpful for the improvement in the economy of a country, but on the other hand, some bad impacts of these resources in the environment have bound us to use these resources within some limit and turned our thinking toward the renewable energy resources. The social, environmental, and economical problems can be omitted by use of renewable energy sources, because these resources are considered as environment-friendly, having no or little emission of exhaust and poisonous gases like carbon dioxide, carbon monooxide, sulfur dioxide, etc.
Volumes | Energy Sustainability | American Society of
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. A renewable electricity generation technology harnesses a naturally existing energy flux, such as wind, sun, heat, or tides, and converts that flux to electricity. Natural phenomena have varying time constants, cycles, and energy densities.
To tap these sources of energy, renewable electricity generation technologies must be located where the natural energy flux occurs, unlike conventional fossil-fuel and nuclear electricity-generating facilities, which can be located at some distance from their fuel sources. Renewable technologies also follow a paradigm somewhat different from conventional energy sources in that renewable energy can be thought of as manufactured energy, with the largest proportion of costs, external energy, and material inputs occurring during the manufacturing process.
Although conventional sources such as nuclear- and coal-powered electricity generation have a high proportion of capital-to-fuel costs, all renewable technologies, except for biomass-generated electricity biopower , have no fuel costs. The trade-off is the ongoing and future cost of fossil fuel against the present fixed capital costs of renewable energy technologies.
Scale economics likewise differs for renewables and conventional energy production. Larger coal-fired and nuclear-powered generating facilities exhibit lower average costs of generation than do smaller plants, realizing economies of scale based on the size of the facility.
Renewable electricity achieves economies of scale prmarily at the equipment manufacturing stage rather than through construction of large facilities at the generating site. Large hydroelectric generating units are an exception and have on-site economies of scale, but not to the same extent as coal-and nuclear-powered electricity plants. With the exception of hydropower, renewable technologies are often disruptive and do not bring incremental changes to long-established electricity industry sectors.
As described by Bowen and Christensen , disruptive technologies present a package of performance attributes that, at least at the outset, are not valued by a majority of existing customers. Christensen observes:. Disruptive technologies can result in worse product performance, at least in the near term.
Disruptive technologies bring to market very different value propositions than had been available previously. Generally, disruptive technologies underperform established products in mainstream markets.
But they have other features that a few fringe customers value. Disruptive technologies that may underperform today, relative to what users in the market demand, may be fully performance-competitive in that same market tomorrow. Traditional sources of electricity generation at least initially outperform non-hydropower renewables. The environmental attributes of renewables are the initial value proposition that have brought them into the electricity sector.
However, with improvements in renewables technologies and increasing costs of generation from conventional sources particularly as costs of greenhouse gas production are incorporated , renewables may offer the potential to match the performance of traditional generating sources. This chapter examines several technologies for generation of renewable electricity. It discusses the technology associated with each renewable resource, the state of that technology, and research and development needs until , between and , and those beyond Wind power uses a wind turbine and related components to convert the kinetic energy of moving air into electricity and other forms of energy.
Wind power has been harnessed for centuries—from the time of the ancient Greeks to the present. Both the development of wind technology and the installation of wind power plants have grown ever since. A typical wind turbine consists of a number of components: rotor, controls, drive-train gearbox, generator, and power converter , tower, and balance of system. In addition, improved understanding and better modeling capabilities have contributed to the rapid introduction of technical improvements.
What were initially small clusters of kW turbines in the early s have grown to clusters of hundreds of machines, including machines of 1. In general, wind speed increases with height, and the energy capture capability depends on the rotor diameter.
Figure 3. In the most common installed machine had hub heights of ft 84 m and a rotor diameter of ft 67 m. Turbines as big as 5 MW have been installed in offshore locations; these have ft m hub height and ft m rotor diameter IEEE, a. The U. As discussed in Chapter 1 , the installed wind power generating capacity worldwide at the end of was 75, MW. In general, the balance of system BOS is the system between the technologies that convert the renewable flux wind or solar into electricity and the electricity grid for power production or load for direct use.
The BOS might include the power-conditioning equipment that adjusts and converts the DC electricity to the proper form and magnitude required by an alternating-current AC load. For wind turbines, it typically includes all the related electronics required to provide the connection to the grid. Besides the mechanical characteristics, the development of the turbine mechanical to electrical conversion characteristics have evolved from machines based primarily on fixed-speed induction generators Type 1 , to variable-speed machines with electronic control Type 2 , and then machines incorporating vastly different outputs and controls Type 3.
These Type 3 machines are able to control for low-voltage ride-through LVRT , 3 voltage, 4 output 5 and ramp rate, 6 and volt-ampere-. Under FERC order A, low-voltage ride-through is the capability to continue to operate down to 15 percent of rated line voltage for 0. This capability keeps the plant from shutting down as a result of short-term voltage fluctuation.
Output control ability allows the power produced to be reduced by feathering the blades. Ramp rate management allows the power output to stay within the increase or decrease limits required by the system. The evolution of control technologies has made wind generators and their electricity output easier to integrate into the utility system. With these new control technologies, wind power plants are better at mimicking traditional generating plants.
It calls for wind facilities of 20 MW or larger to provide the ability. VAR support provides reactive power compensation to aid in electricity grid stability. These power integration capabilities have been incorporated into Type 3 machines. However, wind power generation takes place where and when the wind blows, and electricity must be used when it is generated. This intermittency has raised concerns about integrating wind power into the existing power system and requires wind turbines to provide LVRT, voltage control, output and ramp rate controls, and VAR support.
Integrating Type 3 machines into existing grids is not without its challenges. Circumstances such as wind fluctuations and overall grid stability are unique to each particular control area. Thus, even as technologies improve, it will be critical to carry out site-specific analyses of each control area, which will better aid grid operators in balancing the system within their control area. A number of studies on the integration of wind power into a utility capacity and dispatch structure indicate that wind can be integrated at up to approximately 20 percent of the total electricity mix without requiring storage, although the exact level depends on the power system Parsons et al.
As the studies point out, achieving such levels of renewables penetration will depend on upgrades to the grid necessary regardless of the energy mix and new transmission lines for more remote sources. Modern electricity grid systems are designed to handle loss of the largest power plant without disruption; to have ramp up and ramp down capabilities: and to increase or decrease generation as demand increases or decreases.
However, each system has its own generating capacity structure, transmission capabilities, and ability to purchase power outside its own boundaries, making wind power integration somewhat unique for each utility. The vast majority of wind power is generated by large wind turbines feeding into the electricity grid, while small wind turbines generally provide electricity directly to customers. The United States is the leading world producer of small wind turbines.
The manufacture and marketing of wind-powered electric systems sized for residential homes, farms, and small businesses have experienced major growth in the past decade. These small wind turbines Figure 3. The key technological issues for wind power focus on continuing to develop better turbine components and to improve the integration of wind power into the electricity system, including operations and maintenance, evaluation, and forecasting.
Goals appear relatively straightforward: taller towers; larger rotors; power electronics; reducing the weight of equipment at the top and cables coming from top to bottom; and ongoing progress through the design and manufacturing learning curve Thresher et al. Table 3. Although no big breakthroughs are anticipated, continuous improvement of existing components is anticipated, and many are already being actively developed. For example, there are advanced rotors that use new airfoil shapes specifically designed for wind turbines instead of those based on the design of helicopter blades.
These rotors are thicker at points of highest stress and reduce loads during turbulent winds by flying the blades using turbine control systems. Other improvements include the use of composite materials and advanced drivetrains. In particular, gearboxes are a major area of concern for reliability.
Approaches for improving this component include direct-drive generators; greater use of rare-earth permanent magnets in generator design; possibility of single-stage drives using low-speed generators; and distributed drivetrains using the rotor to drive several parallel generators. Advanced towers are a major focus for innovation, given the current need for large cranes and transport of large tower and blade sections.
Concepts under investigation include self-erecting towers, blade manufacturing on site, vibration damping, and tower—drivetrain interactions. There is certain to be some development of offshore wind in the United States in the near term, but it is not expected that this will have a significant impact before Nonetheless, there is a near-term opportunity to learn from offshore projects in Europe and the United States, if offshore wind is going to have an impact in the medium term.
Other near-term opportunities will lie in improving the integration of existing wind power plants into the transmission and distribution system, which includes using improved computational models for simulating and optimizing system integration Ernst et al.
Chapters 6 and 7 discuss the deployment and integration of wind-generated electricity. Manufacturing and learning curve a. Mid-term wind technology development will have two thrusts: the movement toward offshore, and its implications for turbine design; and the development of efficient low-wind speed turbines.
Development of offshore wind power plants has already begun in Europe approximately MW of installed capacity , but. Nine projects are in various stages of development in state and federal waters. In addition to technical risks and higher costs, these projects have been slowed by social and regulatory challenges DOE, In the mid-term, offshore turbines will have a larger size and generating capacity than onshore turbines, but, owing primarily to technical and cost concerns, development will likely lag behind onshore machines.
Transmission siting issues with offshore wind power plants will be simplified because of fewer siting impediments. However, underwater cables must be carefully constructed, and there will likely be a move to develop microgrids with high-voltage direct current to integrate the offshore resources. Offshore wind technologies face several transition problems as they move from near-shore, land-based sites to offshore sites of various depths and, finally, floating designs.
Assessment tools for sensitive marine areas, wind loads, and system design are not now ready for offshore development. Offshore projects must be built to handle both wind and wave loads, and components must be able to endure marine moisture and extreme weather. Offshore wind projects have a higher balance of station cost approximately two-thirds of total costs than do onshore projects, and thus will rely on cost reductions across the system in order to become more competitive.
All of these developments pose both technological and organizational problems and will require continuous research and development in order to be feasible.
It should be noted that challenges posed by the greater technical difficulties of offshore wind power development are being addressed by other countries. However, political, organizational, social, and economic obstacles may continue to inhibit investment in offshore wind power development, given the higher risk compared to onshore wind energy development Williams and Zhang, In terms of onshore development, as the higher wind speed sites are used, wind power development will move to lower wind speed sites, which will require turbines that are relatively efficient at lower wind speeds, necessitating larger rotors with lighter, stronger materials, as well as increased tower height.
At present, no revolutionary technology to extract energy from wind has been proposed, but several designs, e.
There have been conceptual proposals to access high-altitude winds using balloons or kites. Component improvements will continue, with. Floating offshore platforms may gain interest, but first must come experience from anchored offshore wind facilities.
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Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. A renewable electricity generation technology harnesses a naturally existing energy flux, such as wind, sun, heat, or tides, and converts that flux to electricity. Natural phenomena have varying time constants, cycles, and energy densities. To tap these sources of energy, renewable electricity generation technologies must be located where the natural energy flux occurs, unlike conventional fossil-fuel and nuclear electricity-generating facilities, which can be located at some distance from their fuel sources. Renewable technologies also follow a paradigm somewhat different from conventional energy sources in that renewable energy can be thought of as manufactured energy, with the largest proportion of costs, external energy, and material inputs occurring during the manufacturing process.
For the world to transition to low-carbon electricity, energy from these sources needs to be cheaper than electricity from fossil fuels. Fossil fuels dominate the global power supply because until very recently electricity from fossil fuels was far cheaper than electricity from renewables. This has dramatically changed within the last decade. In most places in the world power from new renewables is now cheaper than power from new fossil fuels. The fundamental driver of this change is that renewable energy technologies follow learning curves , which means that with each doubling of the cumulative installed capacity their price declines by the same fraction. The price of electricity from fossil fuel sources however does not follow learning curves so that we should expect that the price difference between expensive fossil fuels and cheap renewables will become even larger in the future.
Can the World Run on Renewable Energy?
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Historically, great powers have gone to great lengths to guarantee the energy necessary to compete in the international system. Today, as fossil fuel sources diminish and energy demands increase, the most powerful States, specifically China and the United States, are competing for energy resources, including renewable energy sources, while continuing to protect and procure remaining nonrenewable sources around the world. This article examines the efforts being made by China and the United States to maintain and improve their respective energy security, highlighting the incorporation of renewable energy sources. Because energy security is necessary for power, states use energy to guarantee national security and grow their global standing. Energy, therefore, has a central role in the structure, consolidation, and survival of states.
Without doubt, renewable energy is on a roll.