Apparatus using a balloon supported reflective surface for reflecting light from the sun

• US 5,404,868 A
• Filed: 03/31/1992
• Issued: 04/11/1995
• Est. Priority Date: 03/31/1992
• Status: Expired due to Term

• Current Assignee: Vedanta Society Of Western Washington
• Original Assignee: Vedanta Society Of Western Washington
• Inventors: Sankrithi, Mithra M. K. V.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): NGUYEN, HOANG M
• Application Number:
  US07/861,031
• Time in Patent Office: 1,106 Days
• Field of Search: 126/696, 126/697, 126/684, 126/600, 126/604, 126/607
• US Class Current: 126/604
• CPC Class Codes: F24S 2030/115 Linear actuators, e.g. pneumatic cylinders
• CPC Class Codes: F24S 2030/131 in the form of articulated bars
• CPC Class Codes: F24S 2030/135 in the form of threaded elements
• CPC Class Codes: F24S 23/81 flexible F24S23/715, F24S23/745 take precedence
• CPC Class Codes: F24S 30/48 with three or more rotation axes or with multiple degrees of freedom
• CPC Class Codes: Y02E 10/47 Mountings or tracking

Abstract

The invention provides a family of apparatus using a balloon supported reflective surface for reflecting light from the Sun. A basic embodiment of such an apparatus is a light weight, low cost heliostat using a balloon supported reflective surface. Another embodiment is a solar power concentration apparatus using multiple heliostats with balloon supported reflective surfaces. Yet another embodiment is a solar electric power apparatus, also using multiple heliostats with balloon supported reflective surfaces. Variant embodiments of these apparatus can be sited on land or water surfaces or in the air or in space.

Claims

1. A heliostat, comprising a reflective surface with a reflective side and an other side, support means for supporting said reflective surface above a ground surface, said support means comprising an inflated base balloon supported by said ground surface and located between said ground surface and said other side of said reflective surface, and control means for rotationally orienting said reflective surface as a function of time so as to reflect incident solar radiation, falling on said reflective side of said reflective surface from a solar radiation incident direction which is a function of time, to a target region

2. The heliostat of claim 1, wherein said inflated base balloon is an inflated toroidal balloon.

3. The heliostat of claim 1, wherein said support means provide means for supporting said reflective surface above a ground surface.

4. The heliostat of claim 3, wherein said inflated base balloon is an inflated base balloon supported by said ground surface.

5. The heliostat of claim 1, wherein said inflated base balloon maintains a substantially constant shape configuration when said control means changes the orientation of said reflective surface.

6. The heliostat of claim 1, wherein said inflated base balloon maintains a substantially constant volume configuration when said control means changes the orientation of said reflective surface.

7. The heliostat of claim 1, wherein said inflated base balloon as a whole changes orientation along with said reflective surface, when said control means changes the orientation of said reflective surface,

8. The heliostat of claim 1, wherein said reflective surface is a mirror.

9. The heliostat of claim 1, wherein said reflective surface is a stretched membrane reflector.

10. The heliostat of claim 1, wherein said reflective surface is concave on its reflective side.

11. The heliostat of claim 3, wherein said support means further comprises support structure anchored in said ground surface.

12. The heliostat of claim 1, further comprising means for maintaining said reflective surface in a desired shape configuration.

13. The heliostat of claim 12, wherein said reflective surface is a reflective membrane and wherein said means for maintaining said reflective surface in a desired shape configuration comprises means for minimizing reflective membrane deflections.

14. The heliostat of claim 12, wherein said reflective surface is a reflective membrane and wherein said means for maintaining said reflective surface in a desired shape configuration is provided by said support means, which support means further comprises support structure means on the periphery of said reflective membrane for supporting said reflective membrane in tension.

15. The heliostat of claim 12, wherein said reflective surface is a reflective membrane, wherein said desired shape configuration of the reflective surface is concave on its reflective side, and wherein said means for maintaining said reflective surface in said desired shape configuration comprises means for providing differential pressure across said reflective surface, with pressure acting on the reflective surface other side being lower than pressure acting on the reflective surface reflective side.

16. The heliostat of claim 15, wherein said pressure acting on said reflective surface reflective side is ambient pressure, wherein said pressure acting on said reflective surface other side is sub-ambient pressure which is contained in an enclosed volume whose bounding surfaces include said reflective surface above said enclosed volume and a bottom surface below said enclosed volume.

17. The heliostat of claim 12, wherein said reflective surface is a reflective membrane, wherein said desired shape configuration of the reflective surface is concave on its reflective side, and wherein said means for maintaining said reflective surface in said desired shape configuration comprises membrane shaping tether elements.

18. The heliostat of claim 12, wherein said support means for supporting said reflective surface also incorporates said means for maintaining said reflective surface in a desired shape configuration.

19. The heliostat of claim 1, further comprising internal tether means within said inflated base balloon for affecting the shape of said inflated base balloon.

20. The heliostat of claim 1, wherein said inflated base balloon comprises an inflated volume enclosed by plural enclosing surface elements, with adjacent enclosing surface elements attached to each other along seam lines.

21. The heliostat of claim 1, further comprising means for varying the gas pressure in said inflated base balloon.

22. The heliostat of claim 4, wherein said support means further comprises additional support means for contributing to the support of said reflective surface above said base balloon.

23. The heliostat of claim 22, wherein said additional support means comprises an inflated toroidal balloon.

24. The heliostat of claim 22, wherein said additional support means includes a substantially rigid structure of substantially toroidal topology for supporting said reflective surface around its periphery.

25. The heliostat of claim 1, wherein said inflated base balloon includes multiple related inflated chambers.

26. The heliostat of claim 3, further comprising hydrostatic support means for contributing to the support of said reflective surface above said ground surface.

27. The heliostat of claim 3, further comprising aerostatic support means for contributing to the support of said reflective surface above said ground surface.

28. The heliostat of claim 1, with means for inflating said inflated base balloon with a lighter-than-air gas.

29. The heliostat of claim 23 wherein said support means further comprises means for securing said reflective surface around its periphery to said toroidal balloon.

30. The heliostat of claim 1, wherein said inflated base balloon is an elongated approximately linear balloon, and wherein said control means for rotationally orienting said reflective surface provides means for orienting said reflective surface in a single degree of freedom.

31. The heliostat of claim 1, wherein said control means for rotationally orienting said reflective surface provides means for orienting said reflective surface in two degrees of freedom.

32. The heliostat of claim 31, wherein said two degrees of freedom are elevation angle and azimuth angle.

33. The heliostat of claim 1, wherein said control means for rotationally orienting said reflective surface includes at least one controllable positioning motor.

34. The heliostat of claim 1, wherein said control means for rotationally orienting said reflective surface includes an elongated control element and means for controlling effective length of the elongated control element.

35. The heliostat of claim 34, wherein said elongated control element is a control tether.

36. The heliostat of claim 34, wherein said elongated control element is a control rod.

37. The heliostat of claim 3, wherein said control means for rotationally orienting said reflective surface includes at least three elongated control elements, which elongated control elements provide tension links between substantially rigid structure to which said reflective surface is connected, on the first hand, and base elements affixed to said ground surface, on the other hand.

38. The heliostat of claim 37, wherein said substantially rigid structure comprises a substantially rigid control ring.

39. The heliostat of claim 37, further comprising an inflated toroidal balloon , and wherein said substantially rigid structure comprises said inflated toroidal balloon in combination with a plurality of balloon holding frames distributed around the outer periphery of said inflated toroidal balloon and pressed against said inflated toroidal balloon by means of circumferential tension bands.

40. The heliostat of claim 37, with load distribution means for distributing tensile loads from each of said elongated control elements to at least two locations on said substantially rigid structure.

41. The heliostat of claim 1, wherein said control means for rotationally orienting said reflective surface includes computer means for computing the required orientation of said heliostat as a function of time.

42. The heliostat of claim 1, wherein said control means for rotationally orienting said reflective surface is calibrated by calibration means for precisely calibrating the orientation of said heliostat.

43. The heliostat of claim 1, further comprising means for maintaining said reflective surface in good condition.

44. The heliostat of claim 29, wherein said inflated toroidal balloon exerts outward inflation-induced forces tending to maintain said reflective surface in tension.

45. The heliostat of claim 44, wherein said reflective surface is a reflective membrane, wherein a second membrane in tension is also secured around its periphery to said toroidal balloon, and wherein means are provided between said reflective membrane and said second membrane for causing said reflective membrane to deflect to a shape which is concave on the reflective side of said reflective membrane.

46. The heliostat of claim 1, further comprising damping means for damping motions of said reflective surface.

47. The heliostat of claim 1, wherein a solar receiver is located substantially at said target region.

48. The heliostat of claim 47, wherein the solar receiver is attached to the heliostat, wherein the reflective surface is maintained in a configuration which is concave on said reflective side and wherein the area of the target region is substantially smaller than the reflective area of the reflective surface.

60. The heliostat of claim 4, wherein said base balloon executes a rolling motion on said ground surface when said control means changes the orientation of said reflective surface.

49. A solar power concentration apparatus comprising a solar receiver located at a target region and a plurality of heliostats, wherein at least some of said plurality of heliostats are balloon supported heliostats, which balloon supported heliostats each comprises a reflective surface with a reflective side and an other side, support means for supporting said reflective surface above a ground surface, said support means comprising an inflated base balloon supported by said ground surface and located between said ground surface and said other side of said reflective surface, and control means for rotationally orienting said reflective surface as a function of time so as to reflect incident solar radiation, falling on said reflective side of said reflective surface from a solar radiation incident direction which is a function of time, to said target region.

50. The solar power concentration apparatus of claim 49, wherein said balloon supported heliostats are arranged in an orderly pattern above said ground surface, and wherein elements of said control means associated with neigboring heliostats are secured to the ground surface at common points in the interstices of said orderly pattern.

51. The solar power concentration apparatus of claim 49, wherein said solar receiver is upheld at a specific position above said plurality of heliostats.

52. The solar power concentration apparatus of claim 51, wherein said solar receiver is upheld at least partially by aerostatic lift.

53. The solar power concentration apparatus of claim 49, wherein said plurality of heliostats reflect incident solar radiation onto said solar receiver, causing said solar receiver to receive a concentrated solar energy flux, which concentrated solar energy flux heats a working fluid passing through the solar receiver to a high temperature.

54. The solar power concentration apparatus of claim 53, further provided with means for storing heat.

55. The solar power concentration apparatus of claim 53 wherein said solar power concentration apparatus is sited close to locations having deposits of oil shale, further provided with means for utilizing said high temperature working fluid to provide a heat source for retorting said oil shale to extract oil.

56. The solar power concentration apparatus of claim 49, wherein said solar power concentration apparatus is a solar thermal powerplant, which solar thermal powerplant further comprises conversion means for converting at least a portion of solar power received at said solar receiver into electric power.

57. The solar power concentration apparatus of claim 56, further comprising energy storage means for receiving electric power from said conversion means over some time period, storing the energy received over a second time period, and finally transmitting stored energy as electric power over a third time period.

58. The solar power concentration apparatus of claim 56, further comprising two bodies of water at different elevations, pump means for using electric power from said solar power concentration apparatus to pump some water from the lower body of water to the upper body of water when excess solar electric power is being produced relative to electric power consumption, and generator means for generating electric power from the passage of some water from the upper body of water to the lower body of water at times when insufficient solar electric power is being produced relative to electric power consumption.

59. The solar power concentration apparatus of claim 49, further comprising means for moving the solar receiver as a function of time,

61. Solar electric power apparatus for providing electric power to consumers of electric power, comprising:

(i) a plurality of heliostats each comprising a reflective surface with a reflective side and an other side, support means for supporting said reflective surface above a ground surface, said support means comprising an inflated base balloon supported by said ground surface and located between said ground surface and said other side of said reflective surface, and control means for rotationally orienting said reflective surface as a function of time so as to reflect incident solar radiation, falling on said reflective side of said reflective surface from a solar radiation incident direction which is a function of time, to a solar receiver located at a target region;

(ii) generation means for converting at least a portion of solar power carried by the solar radiation reflected by the heliostats to the solar receiver into electric power;

and

(iii) means for transmitting the electric power from the generation means, through conditioning means for conditioning the electric power, to the consumers of electric power.