Solar mirror

From Wikipedia, the free encyclopedia

You have new messages (last change).
This article may require cleanup to meet Wikipedia's quality standards.
Please discuss this issue on the talk page or replace this tag with a more specific message.
This article has been tagged since October 2005.
It has been suggested that this article or section be merged with Solar power satellite. (Discuss)

A solar mirror is a viable means to collect fairly dispersed solar radiation and concentrate it to increase the intensity and redirect to an end user. Several applications have been studied and partially implemented.

Contents

[edit] Solar Thermal Applications

The intensity of Solar thermal energy from Solar radiation at the surface of the earth is fairly diffuse, amounting to a maximum of about 1 kilowatt of energy per square meter of area normal to the direction of the sun, under ideal conditions. To use this energy as direct heat for anything from cooking to powering a heat engine or turbine-electrical generator, this energy must be concentrated, a task normally assigned to flat or parabolic arrays of solar mirrors.

[edit] Terrestrial Application

Such solar thermal systems have been constructed and demonstrated on Earth[1][2]The large Sandia Lab Solar power tower uses a stirling engine heated by a solar mirror concentrator[3]. Another configuration is the Trough System[4].

[edit] Space Power Application

"Solar Dynamic" energy systems have been proposed for various spacecraft applications, including Solar Power Satellite, where a reflector focusses sunlight on to a heat engine such as the Brayton cycle type[5].

[edit] Photovoltaic Augmentation

Photovoltaic cells (PV) which can convert solar radiation directly into electricity are quite expensive per unit area. Some types of PV cell, e.g. Gallium Arsenide, if cooled, are capable of converting efficiently up to 250 times as much radiation as is normally provided by simple exposure to direct sunlight.

In tests done by Sewang Yoon and Vahan Garboushian, for Amonix Corp.[6] photocell percent conversion efficiency actually increased at higher levels of concentration, often by significant amounts, provided external cooling is available to the photocells.

[edit] Terrestrial Application

To date no large scale testing has been performed on this concept. Presumably this is because the increased cost of the reflectors and cooling generally is not economically justified.

[edit] Solar Power Satellite Application

Theoretically, for space-based Solar Power Satellite designs, Solar Mirrors could reduce PV cell costs and launch costs since they are expected to be both lighter and cheaper than equivalent large areas of PV cells. Several options were studied by Boeing corporation[7]. In their Fig. 4. captioned "Architecture 4. GEO Harris Wheel", the authors describe a system of solar mirrors used to augment the power of some nearby solar collectors, from which the power is then transmitted to receiver stations on earth.

[edit] Space Reflectors for Night Illumination

Another advanced space concept proposal is the notion of Space Reflectors which reflect sunlight on to small spots on the night side of the Earth to provide night time illumination.

An early proponent of this concept was Dr. Krafft Arnold Ehricke, who wrote about systems called "Lunetta", "Soletta", "Biosoletta", "Powersoletta"[8][9].

A preliminary series of experiments called Znamya was performed by Russia. The first, designated Znamya-2, was launched aboard Progress-TM-15 on 27 October 1992. After visiting the EO-12 crew aboard the Mir space station the Progress-TM-15 then undocked and deployed the reflector[10] [11] this mission was successful. The next flight Znamya-2.5 failed[12]. Znamya-3 never flew.

One interesting theoretical method to construct such an orbiting Solar Mirror is the "Tension Stabilized Steerable Orbiting Mirror" [13].

[edit] See also

[edit] References

  1. ^ Sandia Labs - CSP Technologies Overview
  2. ^ PowerTower The large design developed by Sandia National Labs
  3. ^ Sandia Lab - Solar Dish Engine
  4. ^ Sandia Lab - Trough System
  5. ^ Mason, Lee S.; Richard K. Shaltens, James L. Dolce, and Robert L. Cataldo (2002-01-XX). Status of Brayton Cycle Power Conversion Development at NASA GRC (PDF). NASA Glenn Research Center. Retrieved on 2007-02-25.
  6. ^ Yoon, Sewang; Vahan Garboushian (pub date unknown). Reduced Temperature Dependence of High-Concentration Photovoltaic Solar Cell Open-Circuit Voltage (Voc) at High Concentration Levels (HTML). Amonix Corp.. Retrieved on 2007-02-25.
  7. ^ Potter, Seth D.; Harvey J. Willenberg, Mark W. Henley, and Steven R. Kent (May 6, 1999). "Potter Architecture Options for Space Solar Power". High Frontier Conference XIV, Princeton, NJ, U.S.A.: Space Studies Institute. Retrieved on 2007-02-25. 
  8. ^ Ehricke, Krafft Arnold (Sept. 1-4, 19). "Power Soletta: An industrial sun for Europe - Possibilities for an economically feasible supply with solar energy". Raumfahrtkongress, 26th: 85-87, Berlin, West Germany: Hermann-Oberth-Gesellschaft. vol. 14, no. 3. Retrieved on 2007-02-25. 
  9. ^ Ehricke, Krafft Arnold (January-February 1978). "The Extraterrestrial Imperative". Air University Review Vol. XXIX (No. 2). Retrieved on 2007-02-25. 
  10. ^ McDowell, Jonathan (1993-02-10). Jonathan's Space Report - No 143 - Mir (HTML). Jonathan's Space Report. Jonathan McDowell. Retrieved on 2007-02-25.
  11. ^ Wade, Mark (pub date unknown). Mir EO-12 (HTML). Encyclopedia Astronautica. Mark Wade. Retrieved on 2007-02-25.
  12. ^ Wade, Mark (pub date unknown). Mir News 453: Znamya 2.5 (HTML). Encyclopedia Astronautica. Mark Wade. Retrieved on 2007-02-25.
  13. ^ Gould, Len. Tension Stabilized Steerable Orbiting Mirror (HTML). self published. Retrieved on 2005-01-03. “TSSOM” (no longer available February 25, 2007)
Retrieved from "http://en.wikipedia.org../../../s/o/l/Solar_mirror.html"