Earth based solar collector

Description

A BRIEF SUMMARY OF THE INVENTION

This invention relates to the collection of sunlight for heat which is used for heating and for the conversion of heat to electricity with a steam or an Organic Rankine Cycle ORC system. Where a large area of land is prepared then covered with a solar collecting film of plastic or glass. The air or water under the film will heat up and is then circulated around the collector over a heat exchanger. This heat exchanger carries a working fluid such as Freon which has been heated to perform work in the ORC system.

BACKGROUND OF THE INVENTION

The invention relates an earth based solar collector. Prior art shows how to create flat-plate or concentrating collectors however, because solar energy is a diffused energy source such devices are of limited practical value for large scale power generating systems as the complexity of such systems when scaled to a large size results in a system cost that exceeds the value of the electricity that can be generated over the useful life of the system. By using the earth itself as the back and side panels of the collector the collector cost drops from dollars per square meter to pennies per square meter. This innovation in collector design will result in lower system efficiency which is at first counterintuitive, however because of the diffused nature of sunlight it will be apparent that reducing the collector cost by an order of magnitude or more will far outweigh any reduction of efficiency. The useful temperature range of this collector will range from 150 degrees Fahrenheit to 450 degrees Fahrenheit. Prior art such as UTC Carrier patent #7,174,716 defines a low temperature ORC system that could be used with this invention.

Objects and Advantages:

Accordingly I claim the following as my objects and advantages of the invention: to provide a solar collector that uses prepared earth as a back plane and a covering plate or plates of plastic or glass. The plastic and glass can be treated to maximize their transmission of sunlight while limiting the re-radiation loss of infrared or heat energy out of the collector. The background of the collector being the earth itself will provide insulation with porous material such as vermiculite or foam insulation and the surface of the earth inside the collector will be painted or sprayed black with black material such as carbon black or a solar selective paint to maximize the ability to absorb sunlight. The angle of the earth will be modified to maximize the collectors light collecting ability, such as bulldozing the land so that the maximum amount of area faces the sun so that the maximum amount of sun light will be received. In this way very large areas of land maybe covered with this solar collector at the lowest possible cost.

In addition I claim the following as objects and advantages of the invention: to provide a solar collector system that can be built in a circular or oval manner so that the air or water inside the collector can be blown or pumped around a circular or oval path so that the hot solar heated air or water can pass through a heat exchanger so the heat can be extracted in the form of steam or a refrigerant such as Freon or other hydrocarbon may be so heated for use in a steam turbine or in the case of heated Freon or other organic fluid may be used in an ORC system for the generation of electricity.

DRAWING FIGURES

FIG. 1 shows a cross section of the solar collector.

FIG. 2 shows a 1,000 meter long collector covering a large area

DRAWING REFERENCE NUMERALS

FIG. 1

• Element 10: insulating material
• Element 20: earth
• Element 30: solar absorbing coating
• Element 40: clear layer #1
• Element 50: clear layer #2
• Element 60: infrared coatings
• Element 65: insulating air-gap
• Element 70: insulating side panel
• Element 75: heated air or water
• Element 80: heat absorbing thermal mass

FIG. 2

• Element 90: heat exchanger
• Element 100: solar collector
• Element 110: fan or pump
• Element 120: Organic Rankine Cycle—ORC system

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an earth based solar collector where the earth 20 has been formed into a solar collector and has been formed at angles to maximize the absorption of sunlight. An insulation material 10 is used under the heat absorbing mass 80 to limit heat loss into the ground below the collector. This mass which can be water retains the collected heat above the insulation acting as a thermal buffer. The collector is covered with one or more clear membranes 40 and 50 such as glass or plastic or both. This membrane may be treated with an infrared retention coating 60 internally or externally. The sides of the collector maybe formed from the earth or insulating side panels 70 may be used.

FIG. 2 shows a large scale earth based solar collector. To extract the heated air or water 75 which is circulated with a fan or a pump 110. This heated air or water then passes over the heat exchanger 90 heating a working fluid such as Freon for use in the Orgainc Rankine Cycle system 120.