CA3009370A1 - An optical mechanism for solar energy generation - Google Patents

Description

AN OPTICAL MECHANISM FOR SOLAR ENERGY GENERATION.
This invention relates to an optical mechanism for solar energy generation.
Parabolic troughs are useful means for concentrating solar rays for clean energy generation on the ground and electric generation for satellite communication. They basically consist of parabolic mirrors, directional control mechanisms, and water heating pipes, steam turbine and electric generator. The parabolic mirrors are mounted onto the direction control mechanism so that they point towards the sun and follow it in day time hours to intercept the maximum amount of solar radiation. Solar thermal equipment consists of large mechanical and optical equipment such as parabolic troughs, absorber water, and solar tracking equipment. The receiver is located at the focal point of the parabolic troughs. The parabolic troughs focus the solar rays to heat the water inside the absorber tube converting it to steam. The steam is then used for power generation via the turbines and electric generator.

2 However, existing parabolic mirrors have a number of disadvantages which limit their wide spread use. They are made of mirrors which consist of solid glass and other reflecting surfaces. The solid materials require manufacturing, transportation, installation and maintenance which increase costs. Solid components are also difficult to scale up. Their size is another problem. An average parabolic mirror has ten times the size of the common satellite dish. Therefore they cannot be used for individual homes and buildings or small villages for rural electrification where energy is required most.
The solid material of parabolic mirror is rigid and cannot be extended or adjusted to meet customer requirements and advanced product development. For advanced product.
They also rely on reflection for focusing solar radiation in which the reflecting surface absorbs some of the energy causing energy losses.

3 They require large areas of land and must be must be installed in remote desert locations.
A large solar farm may consist of 3000 parabolic mirrors and generate around 300 Megawatts of power and occupy 2000 acres of land and provide power for 73,000 homes. This increases the energy generation cost for the customer.
It is therefore important to design an alternative method which vertically oriented and the focusing of solar rays takes place in the atmosphere.
Space-based solar has a major advantage. Solar energy is only available during the day on earth and not available at night. However solar energy is available during the day and night in outer space and hence providing a more reliable energy source. But it is difficult and expensive to deploy and use existing solar equipment in outer space. Parabolic mirrors and electric generator require large rockets to carry them into space in one piece.

4 They are difficult to assemble in outer space. Ground based solar equipment is affected by weather conditions and clouds but this problem does not exist in outer space. Solar energy intensities are higher in outer space that on earth. But existing solar equipment is too heavy to be installed in outer space.
Integrating solar energy with fossil fuel burning power plants is required for reducing carbon emissions. However, electric generator and wind turbines require large areas for their installation and hence are difficult to integrate with power plants.
The earth receives around 1000 Watts per square meter of energy during the day and it is estimated that it emits 100 million gigawatts as infrared into the atmosphere. This has the potential to meet the energy shortage on earth. Existing solar equipment cannot harvest this energy source and Nanoantennas, rectinnas and nanotubes are currently under development

5 provide but both method are not suitable for harvesting infrared energy due to their limited surface areas.
Existing solar thermal equipment therefore fall short of meeting the increasing demand for clean energy particularly in developing countries with limited income.
In this invention there is provided optical mechanism for solar energy generation consisting a laser diode 1, an axicon 2, receiver 4, battery 5, steam turbine 7 and tracking mechanism 8, perforated frame 9 and support frame 10 in which the battery is connected to the laser diode to generate a Gaussian laser beam 6a which the impinges on the axicon 2 which converts the laser beam into a hollow cone or a Bessel beam 6b to further receive the incoming solar radiation 11 and in which further laser beams have a suitable wavelength for atmospheric water vapor absorption so that the air layer in the atmosphere around the laser

6 beams making up the hollow cone are heated to a higher temperature than the surrounding air thus changing the refractive index of the air and generating a mirage effect in the atmosphere and in which further the incoming solar radiation is incident on the heated air layers at a suitable angle of incidence to cause a total internal reflection and hence focus the incoming solar radiation onto The receiver 4 further connected to the steam turbine 7 for power generation as directed by the tracking mechanism 8 thus providing a non-solid optical method of focusing solar rays on a larger scale than is possible with existing parabolic mirrors.
Mirages depend on heat generation and do not require factory manufacturing. They are also non solid. They require less equipment and low energy input for mirage generation and directional control. They can

7 also cover large areas in the atmosphere and reduce the amount of land area required.
The heated air layers are non-solid and require no factory manufacturing, transportation, installation and maintenance. The solar rays are reflected from the heated air layer because their refractive index is lower than that of the surrounding air. Therefore they act like mirrors and reflect the solar rays. The solar rays are then focused on the receiver located at the focal point of the laser diodes heated air layers.
The atmosphere contains both CO2 and water vapor which absorb infrared radiation for heating the air layer. The heated air layer can be generated in outer space, urban and rural areas more conveniently than existing equipment. The laser diodes beams point upwards and the vertical orientation of the heated air layers always point towards the sun.

8 The non-solid design can be extended by increasing the area which the infrared laser cover to meet customer energy output requirements and for more advanced product development.
The present invention relies on total internal reflection of solar radiation which has 100% efficiency rather than normal reflection in solid mirrors which has a lower efficiency thus increasing the utility of the invention.
Existing solar thermal farms occupy much land surface due to their horizontal orientation. In our proposal the rotating laser diodes beams can cover large areas in the atmosphere to reduce land use for increasing

9 output and are hence more suitable for meeting the increasing for clean energy than existing solutions.
There are two types of laser diodes beams i.e. Continuous wavelength (CW) laser diodes r beams and pulses wave (PW) laser diodes r beams.
Continuous wave laser diodes beams tend to lose their intensity or attenuate during their propagation in the atmosphere.
This is due to their encounter with dust particles, moisture and other chemicals. Laser diodes beams are therefore prone to loss of focus strength and heating capacity. These losses reduce the distance which the CW laser diodes beam travels in the atmosphere and hence their atmosphere air layer heating performance and mirage formation. The losses increase at distance greater than 0.5 km in most of the existing laser diodes machines.
This means the mirage formation can take place within this distance by using different types of laser diodes machine and laser diodes beams of different wave length thus extending the utility of this invention.

10 The heated air layers can therefore cover large areas of 1 km diameter without losing their intensity for solar energy generation. Parabolic mirrors of this size are difficult to manufacture and the invention therefore extends solar energy generation capacity with simplified solar equipment. Pulse beam laser diodes beams consist of energy packets with higher intensity and hence can cover larger distances with losing their coherence and atmospheric heating capacity. This invention utilizes pulsed laser diodes for distance larger than 0.50 km to enhance its utility for mirage generation and solar energy generation.
The ax icon converts the normal laser beam into a cone shaped Bessel beam as shown in Fig. 2. The laser beams overlap after the leaving the axicon lens which results into constructive interference of the laser in the overlap area. Normal laser beam are prone to attenuation but the Bessel beam can cover larger distances with attenuation thus increasing the efficiency of heated air layer and hence mirage formation thus enhances the utility of the invention further.
The invention consists of few components and hence has the capacity to be integrated in existing power plants to enhance the reduction of carbon

11 emissions. Furthermore, power plants generate water vapor and steam into the atmosphere and these can be used for infrared absorption and mirage generation due to their high concentration around cooling towers thus extending the utility of the invention further. During the day when the sun is shining the invention is used for concentrating incoming solar rays. During the night when the sun is not shining the invention can be used for concentration infrared energy which the earth emits into the atmosphere thus insuring continuous and reliable energy generation.
Furthermore, the earth receives large amounts of solar radiation during the day and reemits millions of gigawatts of infrared energy during the night and this can an important clean source. The problem is that existing technologies are not suitable for harvesting this energy source due to their limited surface area. The mirage effect can cover large areas in the atmosphere and has the potential to refract and focus infrared rays thus increasing the utility of the invention to improve energy access during the night when solar energy is not available thus extending energy access particularly in tropical regions.

12 The non-solid solar energy increases the surface area of parabolic to reduce the amount of equipment and land use and hence has the capacity to reduce energy generation costs for the customer for more affordable energy access especially in developing countries.
The invention therefore has the capacity to overcome the above problems facing space based and other solar energy generation methods.

13 An embodiment of the optical mechanism for solar energy generation Mechanism will now be described using the following drawing in which:
Fig. 1 shows the laser diode, an axicon, concave mirror, receiver fixed inside the support frame and the receiver connected to the steam turbine as well as the location of the tracking mechanism perforated frame and support frame.
Fig. 2 shows detail of the laser diode, an axicon , concave mirror , receiver with the laser beams incident on the axicon forming the Bessel beam to receive and focus the incoming solar radiation and their focus on the receiver.
Fig. 3 illustrates the law of refraction in layer of air layer at different temperatures and hence refractive index and the deflection of light herein for mirage generation.

14 Fig. 4 shows a comparison of atmospheric water and carbon dioxide infrared absorption spectrum.
Fig. 5 shows method of focusing solar radiation using the external circular surface of Bessel beam during the day time and infrared radiation during the night.

15 According to the accompanying drawings the optical mechanism for solar Energy generation mechanism consists consisting a laser diode 1, an Axicon 2, receiver 4, battery 5, steam turbine 7 and Tracking mechanism 8, perforated frame 9, support frame 10, rotation Motor 20 and rotation platform 21.
The laser diodes diode 1 is mounted facing the axicon as shown in Fig. 1 and Fig. 2. The laser diode 1 and connected to the battery 5 as shown in Fig. 1 and Fig. 2. The laser diode 1 , battery 5 are installed on the metal frame 10 and housed in a perforated casing 9 as shown in Fig. 1. The tracking mechanism is connected to the support frame 10 as shown in Fig.
1. The rotation motor 20 is connected to the rotation platform 21 supporting the laser diodes 1 as shown in Fig. 5.

16 Mirages form in nature in hot weather or desert conditions or on tarmac roads on sunny days as illustrated in Fig. 3. The dark surface of the asphalt first absorbs energy from the sun. This in turn heats up the air layer L1 immediately above the road surface to a temperature Ti while the air layer L2 above it remains at normal temperature T2 as shown in Fig. 2.
This results into two air layers at different temperatures and hence different refractive indexes n1 and n2. The two air layers are separated by an interface X1-X2.
The light AB passing from the cooler air layer L2 to hooter air layer L1 is first refracted from its original path BC to BD a shown in Fig. 3. Then on further increase of the angle of incidence an incoming light is reflected back into the atmosphere along BE causing total internal reflection at 100 %

17 efficiency. This because the interface between the two air layers act like mirrors and reflect light rays thus result into a mirage effect. The temperature difference of the heated air layers is only 2 or 3 Deg. C.
Which lower the energy consumptions and hence increases the utility of the invention?
The earth's atmosphere contains water vapor as well as 0.04 % or 400 PPM of carbon dioxide. This is a small but important quantity because carbon dioxide absorbs heat and has an important role in global warming.
The heat absorption happens because the gas molecules absorb infrared radiation at different wavelength.
Water and carbon dioxide consist of polar molecules which absorb infrared radiation at a suitable wavelength. The molecules act like masses connected by a spring mechanism and hence vibrate and reemit the infrared energy of a suitable frequency. Water molecules change from steam to liquid on cooling and hence do not cause global warming. Carbon

18 dioxide remains as gas and continues to absorb infrared energy at these wavelengths as a gas and hence causes global warming.
Fig. 4 shows a comparison of the infrared absorption spectra of water and carbon dioxide. Carbon dioxide contributes towards global warming by trapping and absorbing infrared radiation which the earth emits. But the absorption depends on the wavelength and hence varies as shown in Fig.
4. It is important to avoid using laser energy which increases the global warming effect.
This invention therefore utilizes laser beams where absorption of the gas is lowest as shown by the dark arrows at wavelengths 4-5 microns and 15-17 microns. It is preferable to utilize the lower former wavelength as it has a higher energy density than the latter and hence more suitable for temperature and refractive index gradient generation in the atmosphere for more efficient mirage formation.
The battery 5 is connected to the laser diode 1 to generate a laser 6a as shown in Fig. 2. This laser beam is then incident on the axicon 2 which converting it into a Bessel beam which expands further as it travels through

19 the atmosphere to result into a heated air layer for mirage generation. Solar energy generation is achieved as follows.
The incoming solar radiation 11 is incident on the heated air layer at an incident angle (a) as shown in Fig. 2. If the value of this angle is large enough then total internal reflection takes place. In this case all the energy in the solar rays is reflected to focus on the receiver 4.
The Bessel beam 6b formed by the axicon is more coherent than that of the laser beam and can travel more distance without losing much of it power thus enhancing mirage generation efficiency of mirage generation and performance of the present invention.
Furthermore, the Bessel beam consists of concentric circles of laser beams as shown in Fig. 2. The incoming solar radiation passes between the concentric laser beam and undergo total internal reflect and hence the concentric beams act like wave guides for the incoming solar radiation much like fiber optic cables. This facilitates the focusing of the solar

20 radiation from large areas in the open atmosphere thus enhancing the utility of the invention further.
Our proposal is therefore different from existing solutions in a number of ways. The heated air layers are non-solid and require less manufacturing, transportation, installation and maintenance. The solar rays are reflected from the heated air layer because their refractive index is lower than that of the surrounding air.
Therefore they act like mirrors and reflect the solar rays. The solar rays are then focused on the receiver located at the focal point of the laser diodes heated air layers. The atmosphere contains both CO2 and water vapor which absorb infrared radiation for heating the air layer.
The heated air layer can be generated in urban and rural areas more conveniently than existing solutions. The laser diodes beams point upwards towards the sun as shown in Fig. 1.

21 Existing solar thermal farms occupy much land area due to their horizontal orientation. In our proposal the laser hollow cone can cover large areas in the atmosphere for increasing output and are hence more suitable for meeting the increasing for clean energy than existing solutions.
Infrared radiation is used for remote sensing, infrared sounding, atmospheric profiling, astronomy and many other important purposes.
The process is therefore environmentally friendly and does not introduce foreign material into the atmosphere. Our proposal is a new concept but the existing knowledge will assist our proof of concept.
High temperatures are not required for mirage generation. The main requirement is a temperature difference which is only 2 or 3 Deg. C as can be observed from the natural setting of mirage generation.

22 This minimizes the energy input into the process of focusing solar rays compared to existing solar thermal farms.
The price of clean energy generation has been falling in the past thirty years to make it more and more affordable and compete with the price of oil. Solar panel provides a good example. The price of clean energy generation from electric generator was $77 per Watt in the 1970's. The current price is $ 1 per Watt. The price for residential electricity price range from 1 cent to 2 cent per Watt. Clean energy is therefore still too expensive to compete with fossil fuels which have a much higher energy density.
Our business model is to continue this trend to make clean energy affordable in developing countries. This cannot be achieved with existing technologies due to their low efficiency and old designs.
More portable and higher energy density products are required for this purpose.

23 We believe this also a practical way for achieving carbon emissions, meet climate change mandates sustainable development for rural communities The electric power generated must be first taken to the nearest power plant via high voltage transmission lines to reduce the voltage and then retransmitted to rural areas. This has two major disadvantages.
The long distance power transmission requires the installation of large infra structures which increasers costs.
Existing energy generation products were designed decades ago when energy supply was plenty and pollution levels were low or unknown.
Machine efficiency and environmental protection were therefore hardly a part of the equation at design stage. These technologies are based on linear designs which rely on increasing equipment size for more output. For example, existing solar cells and wind turbines have one thing in common.
They have a low efficiency of around 10-20% and hence fall short of meeting the clean energy affecting many regions of the world.

24 New and more sustainable industrial products are therefore required. Size increases manufacturing, installations, transportation; processing and operation costs thus make these technologies too costly for large scale utilization in vast and isolated rural areas.
Silicon is a major component of solar cells and the capacity for clean energy conversion is fixed by the chemical properties which cannot be changed. The design of wind turbines has not changed for decades and is still based on that of ancient wind mills. These constraints limit the clean energy generation capacity. Wind turbines rely on increasing the size of the blades for more energy generation due to this old design. This contributes to high component costs.
Rural areas require clean energy generation equipment and high efficiency and also affordable at the same time. These design requirements are difficult to achieve in existing technologies. We believe designs taken from natural systems such electric resonance have the capacity to make this design challenge possible.

25 Green technology is also closely linked to natural systems and this design approach can be useful for future product development.
Solar thermal equipment consists of large mechanical and optical equipment such as parabolic troughs, absorber water, and solar tracking equipment.
The receiver is located at the focal point of the parabolic troughs. The parabolic troughs focus the solar rays to heat the water inside the absorber tube converting it to steam.
The steam is then used for power generation via the turbines and electric generator. The Parabolic troughs are the major component of solar thermal installation. They are made of mirrors which consist of solid glass which requires manufacturing, transportation, installation and maintenance.
It is estimated that half of the solar energy reaching the earth consists of infrared radiation. However existing clean energy generation is not designed to make use of infrared radiation for energy conversion.

26 In our proposal the reflecting medium utilizes infrared laser diodes beams for solar focusing and has the capacity to harvest more infrared radiation than existing solutions to provide cheaper and more efficient clean energy method but more tests and prototyping are required.
Moreover, they centralized and cannot be used in smaller units for individual homes and buildings or small villages for rural electrification where energy is required more directly.
They require large areas of land and must be must be installed in remote desert locations. They cannot be installed in urban areas where energy is needed most. They are too large to fit on top of buildings because of the enormous size of the parabolic mirrors. Also, more parabolic troughs are required for increasing output. Solar thermal farms therefore require more investment to meet the demand for more clean energy.

27 Our proposed method utilizes heated air layers which will be cheaper to manufacture and maintain than existing solutions consisting of the solid materials listed above and hence has the potential to compete with them in the market.
Space-based solar energy holds much hope for clean energy supply but the weight of electric generator is major challenge is the high cost of deploying equipment made of solid materials in outer space.
It is therefore important to design an alternative and a more suitable method I for space applications. In this invention we propose here an alternative method which is based on the natural concept of mirages.
Solar rays are made of electromagnetic waves and therefore travel at different speed in different mediums depending on medium density. Air at high temperature has a lower density than air at lower temperature. Solar rays travel faster in the air layer at the higher temperature than that of the

28 lower temperature. The difference in in the speed causes the solar rays to deflect, refract or change direction.
It is important to reduce carbon emissions from existing power plants to protect the environment. From the above we can see that infrared energy absorbs carbon dioxide and water vapor and generated heated air layers for mirage generation.
Infrared energy is within the solar spectrum and hence obeys the laws of reflection and refraction described above for incoming solar radiation. It is estimated that the earth receives millions of gigawatts of infrared radiation during the day when the sun is shining in tropical regions.
This is then then re-emitted during the night. Existing retinas are too small to harvest this energy source.
But the present invention has a large surface area for harvesting this energy source. This will be useful for developing countries t in tropical areas facing energy shortages due to high solid equipment costs.

29 The other problem is that carbon emissions concentration is are already high in the atmosphere and bound to increase due to industrial activities in developed countries. The emissions are causing increasing pollution levels and global warming and must be controlled to safe levels. However existing solid equipment is too costly to use on such large scale. The present invention can provide a more affordable method for reducing carbon emissions.
Alternatively, two adjacent laser beams 6D and 6E can be rotated on a horizontal plane in the air to simulate the mirage effect explained above. A
rotation platform 21, a battery 5 and an electric motor 20 are provided for this purpose as shown in Fig. 5. In this version of the invention the circular outer surface of the laser beam receive the incoming solar 11 radiation as shown in Fig. 5. Total internal reflection takes place at a tangentially and the solar radiation is then focused on an energy absorber 14 for steam end power generation. The rotating laser beams can generate the mirage effect on a large area. Furthermore, the earth's infrared radiation 12 coming

30 from the ground level below the energy absorber can also be focused during the night in a similar manner thus extending the utility of the invention. This arrangement is suitable for replacing large solar farms with minimum equipment to reduce solar energy costs further.
The invention therefore has the capacity to overcome the problems mentioned above facing solar energy equipment.