Power from the Sun: Its Future
22 Nov 1968-Science (American Association for the Advancement of Science)-Vol. 162, Iss: 3856, pp 857-861
About: This article is published in Science.The article was published on 1968-11-22. It has received 786 citations till now. The article focuses on the topics: Energy source & Renewable energy.
Citations
More filters
TL;DR: It is concluded that a broad range of intensive research and development is urgently needed to produce technological options that can allow both climate stabilization and economic development.
Abstract: Stabilizing the carbon dioxide-induced component of climate change is an energy problem. Establishment of a course toward such stabilization will require the development within the coming decades of primary energy sources that do not emit carbon dioxide to the atmosphere, in addition to efforts to reduce end-use energy demand. Mid-century primary power requirements that are free of carbon dioxide emissions could be several times what we now derive from fossil fuels (approximately 10(13) watts), even with improvements in energy efficiency. Here we survey possible future energy sources, evaluated for their capability to supply massive amounts of carbon emission-free energy and for their potential for large-scale commercialization. Possible candidates for primary energy sources include terrestrial solar and wind energy, solar power satellites, biomass, nuclear fission, nuclear fusion, fission-fusion hybrids, and fossil fuels from which carbon has been sequestered. Non-primary power technologies that could contribute to climate stabilization include efficiency improvements, hydrogen production, storage and transport, superconducting global electric grids, and geoengineering. All of these approaches currently have severe deficiencies that limit their ability to stabilize global climate. We conclude that a broad range of intensive research and development is urgently needed to produce technological options that can allow both climate stabilization and economic development.
1,396 citations
TL;DR: The authors pointed out that the economic profession is the most opportunistic of all, and that economists' attention has continually shifted from one problem to another, the problems often being not even closely related.
Abstract: There is an appreciable grain of truth in one of Percy Bridgman's remarks that the economic profession is the most opportunistic of all. Indeed, economists' attention has continually shifted from one problem to another, the problems often being not even closely related. Search all economic periodicals of the English-speaking world before 1950, for example, and you will hardly find any mention of "economic development." It is curious, therefore, that economists have over the last hundred years remained stubbornly attached to one particular idea, the mechanistic epistemology which dominated the orientation of the founders of the Neoclassical
801 citations
TL;DR: This analysis is but a preliminary investigation of a significant agricultural problem that deserves careful attention and greater study before the energy situation becomes more critical.
Abstract: The principal raw material of modern U.S. agriculture is fossil fuel, whereas the labor input is relatively small (about 9 hours per crop acre). As agriculture is dependent upon fossil energy, crop production costs will also soar when fuel costs increase two- to fivefold. A return of 2.8 kcal of corn per 1 kcal of fuel input may then be uneconomical. Green revolution agriculture also uses high energy crop production technology, especially with respect to fertilizers and pesticides. While one may not doubt the sincerity of the U.S. effort to share its agricultural technology so that the rest of the world can live and eat as it does, one must be realistic about the resources available to accomplish this mission. In the United States we are currently using an equivalent of 80 gallons of gasoline to produce an acre of corn. With fuel shortages and high prices to come, we wonder if many developing nations will be able to afford the technology of U.S. agriculture. Problems have already occurred with green revolution crops, particularly problems related to pests (57). More critical problems are expected when there is a world energy crisis. A careful assessment should be made of the benefits, costs, and risks of high energy-demand green revolution agriculture in order to be certain that this program will not aggravate the already serious world food situation (58). To reduce energy inputs, green revolution and U.S. agriculture might employ such alternatives as rotations and green manures to reduce the high energy demand of chemical fertilizers and pesticides. U.S. agriculture might also reduce energy expenditures by substituting some manpower currently displaced by mechanization. While no one knows for certain what changes will have to be made, we can be sure that when conventional energy resources become scarce and expensive, the impact on agriculture as an industry and a way of life will be significant. This analysis is but a preliminary investigation of a significant agricultural problem that deserves careful attention and greater study before the energy situation becomes more critical.
755 citations
TL;DR: The idea of wireless power transfer (WPT) has been around since the inception of electricity and Nikola Tesla described the freedom to transfer energy between two points without the need for a physical connection to a power source as an?all-surpassing importance to man? as discussed by the authors.
Abstract: The idea of wireless power transfer (WPT) has been around since the inception of electricity. In the late 19th century, Nikola Tesla described the freedom to transfer energy between two points without the need for a physical connection to a power source as an ?all-surpassing importance to man? [1]. A truly wireless device, capable of being remotely powered, not only allows the obvious freedom of movement but also enables devices to be more compact by removing the necessity of a large battery. Applications could leverage this reduction in size and weight to increase the feasibility of concepts such as paper-thin, flexible displays [2], contact-lens-based augmented reality [3], and smart dust [4], among traditional point-to-point power transfer applications. While several methods of wireless power have been introduced since Tesla?s work, including near-field magnetic resonance and inductive coupling, laser-based optical power transmission, and far-field RF/microwave energy transmission, only RF/microwave and laser-based systems are truly long-range methods. While optical power transmission certainly has merit, its mechanisms are outside of the scope of this article and will not be discussed.
745 citations
Cites background from "Power from the Sun: Its Future"
...Though still in the experimental stage, researchers working in SPS have made advancements in energy conversion at great distances and high powers (greater than 1 W) to enable electricity to be shared via radio waves, namely collecting solar energy in orbital stations around earth and beaming it to ground stations via microwave power transfer [5], [6], [7]....
[...]
IMEC1
TL;DR: The feasibility of harvesting is discussed, leading to the conclusion that RF energy transport is preferred for powering small sized sensors by radio-frequency energy harvesting or transport.
Abstract: This paper presents an overview of principles and requirements for powering wireless sensors by radio-frequency (RF) energy harvesting or transport. The feasibility of harvesting is discussed, leading to the conclusion that RF energy transport is preferred for powering small sized sensors. These sensors are foreseen in future Smart Buildings. Transmitting in the ISM frequency bands, respecting the transmit power limits ensures that the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure limits are not exceeded. With the transmit side limitations being explored, the propagation channel is next discussed, leading to the observation that a better than free-space attenuation may be achieved in indoors line-of-sight environments. Then, the components of the rectifying antenna (rectenna) are being discussed: rectifier, dc-dc boost converter, and antenna. The power efficiencies of all these rectenna subcomponents are being analyzed and finally some examples are shown. To make RF energy transport a feasible powering technology for low-power sensors, a number of precautions need to be taken. The propagation channel characteristics need to be taken into account by creating an appropriate transmit antenna radiation pattern. All subcomponents of the rectenna need to be impedance matched, and the power transfer efficiencies of the rectifier and the boost converter need to be optimized.
629 citations
References
More filters
01 Jan 1967
TL;DR: In this article, the authors proposed a power transmission line to carry 100 GW (1011watts) of direct current over a distance of 1000 km, where the power must be transmitted as direct current, rather than as alternating current, because the very large (comparatively) alternating-current losses would require excessive refrigeration capacity.
Abstract: As an application of high-field, high-current superconductors we sketch the design of a power transmission line to carry 100 GW (1011watts) of direct current over a distance of 1000 km. (It is interesting to note that the present peak power generating capacity of the United States is approximately 200 GW, or just twice the capacity of the proposed line.) Such a line, in contrast to one made of ordinary metal, would dissipate none of the power transmitted through it, although it is necessary to tap power from the line for refrigeration. The consequences of negligible transmission loss are substantial: power transmission would be more economical than the present practice of shipping coal to the region in which electricity is generated and consumed; generating-plant site selection could be made almost entirely on economic considerations; at the same time, thermal and air-pollution problems could be minimized; novel power sources could be considered. The power line would be made of Nb 3 Sn and would be refrigerated to 4°K. The power must be transmitted as direct current, rather than as alternating current, because the very large (comparatively) alternating-current losses would require excessive refrigeration capacity. Specifically, we shall discuss a line at 200 kV carrying 0.5 × 106A. The investment in the line will be approximately $806 million, or $8.06/kW. Of this, some $6.06/kW is line cost, the remainder being converter cost, which, of course, is the same for an ordinary dc line. In comparison with the shipping of coal, the investment cost would be repaid in ten months. We have investigated in some detail the problems of refrigeration along the line, including those of heat leak through the wires which deliver power to customers at room temperature. The efficiency of the line is greater than 99.9 percent (power transmitted less the power drawn off to run refrigeration equipment, all divided by transmitted power). While the technical discussion is probably correct, the cost figures do not include engineering expeditures and do not consider in detail the costs involved in providing the redundancy and safety factors for, say, a failure rate of one per ten years with a time of a few seconds to restore power. This is not an engineering study but rather a preliminary exploration of feasibility. Provided satisfactory superconducting cable of the nature described can be developed, the use of superconducting lines for power transmission appears feasible. Whether it is necessary or desirable is another matter entirely.
74 citations
TL;DR: The long-range planning of research for an oil-energy company requires a continuous appraisal of all factors; political, social, economic, and technological, that might affect the energyconsumption pattern of the future, even beyond the next 20 or 30 years when other studies of this type usually stop.
14 citations
13 citations
01 Apr 1968
TL;DR: In this paper, thermal analysis of large flexible paraboloid antenna indicates RF losses due to thermal distortions significant for X band and higher transmissions for X-band and higher frequency bands.
Abstract: Thermostructural analysis of large flexible paraboloid antenna indicates RF losses due to thermal distortions significant for X band and higher transmissions
1 citations