Thursday, December 6, 2007

Cheaper than Coal – Developing A Solar Power Supply

Cheaper than Coal

According to what I have read recently, the people over at Google are planning to spend tens or even hundreds of millions of dollars on research into renewable energy sources that are ‘cheaper than coal’. This has spurred me to begin research on the development of a solar cell based upon phosphorescence, which is the most logical and sensible approach to take towards developing a renewable energy source. The more research I do, the more I become convinced that all the pieces required to implement this technology are already in existence, and that it is just a matter of putting the pieces together in the right way. This is doable.

No other invention would do more to benefit the human race at this point in time than the development of a proper solar battery. If you are concerned about such things as human impact on the environment, in particular deforestation in undeveloped countries, for the primitive purpose of generating energy by burning wood, then this technology offers a solution. A proper solar cell does not require the investment of hundreds of billions or even trillions of dollars in utility infrastructure, and if developed cheaply enough, is capable of revolutionizing life by delivering inexpensive (free) power to people all over the world (the cost of the power would be the cost of purchasing the device, while the power of the sun is free)…It goes without saying that such a device would also spur development since the cost of energy is greatly reduced, which then acts as a stimulus. As well the building materials of the future will be based upon complex carbon composites, rather than upon wood from forests, and for this reason it has always seemed ruinous to me that people would be burning up the oil and burning up the coal, since in effect they are burning up the future when they do so.

Phosphorescence: nature’s solar battery

Nature has already supplied us with the fundamental components of a solar power device.
Phosphorescent substances are natural solar collectors that also incorporate a battery. Conventional solar power devices, as they exist today, rely upon silicon and require a separate battery for storage, which is much less efficient than the method already employed by nature.

One of the problems with nature’s solar cell is that the battery ‘leaks’. You may be familiar with phosphorescent material if you have ever had a glow in the dark novelty toy. The device captures photons of light and then gradually over a period of time releases the photons, and is this gradual release of stored energy that is responsible for the glow in the dark effect. Phosphorescent material glows after exposure to light because light energy is stored (the battery effect) but the battery is ‘leaky’ (the glowing effect, which eventually fades completely when the battery has been drained).

Some materials are transparent to certain types of radiation, while having the ability to absorb other forms of radiation. As one example, a human being or a wall in a house is transparent to radio waves, which is why people can listen to a radio within their home, since the radio wave frequencies pass transparently through walls. Human beings are not transparent to UV radiation, but rather absorb this form of radiation, which then explains why people get sunburned.

Phosphorescent material is not transparent to certain portions of the spectrum and thus is able to absorb light energy. One of the fundamental principles of quantum physics states that a phenomenon such as light is composed of discrete packets or quanta (in the case of light this packet is known as a photon). Such quanta are discrete because they can only assume certain fixed energy levels, and we speak of ‘quantum jumps’ between these various steps, since there are no intermediate values, and thus the energy levels of such quanta are said to be discrete and not continuous. This is demonstrated by the lines of the spectra which take the form of discrete bands. The energy level available to any quanta, such as a photon or an electron, is described by four quantum numbers, which together describe all the available discrete energy levels of that particle.

A substance is able to absorb radiant energy when the energy level of the radiation matches one of the fixed energy levels of that quanta. If no exact match can be made, the substance exhibits transparency to that radiation, while if the energy level of the quanta combined with the energy level of an electron about a nucleus results in am exact match for one of the higher energy levels available to an electron, then the result is that the electron absorbs energy, and is raised to what is referred to as an ‘excited’ state, leaving behind the normal state of that electron which is referred to as the ground state.

When a photon of light is absorbed by an electron in an atom of a phosphorescent material the electron does a quantum jump to a higher level excited state, which is short lived. The electron then falls into an intermediate state which lies between the excited state and the normal ground state, which is referred to as a metastable state. When the electron reaches this metastable state, there exists no quanta of energy that is allowed that the electron could release so as to allow the electron to return to the ground state, and for this reason returning to ground is referred to as a condition which is ‘forbidden’. The metastable state thus forms an energy trap and this energy trapping characteristic is the basis of the battery storage potential of phosphorescent material, which is capable of capturing photons emitted by the sun and then converting these photons to useful electrons, which then are held within a type of energy trap from which escape for the electron is forbidden due to the lack of an existing allowable quantum energy level. In order for the electron to release energy and drop back to ground the energy of the emission must exactly match the difference between the energy of the metastable state and the ground, and since no such match can be found to exist, the electron becomes a store of energy transferred by the photon of light which the electron is unable to release.

A metastable state is not stable, for if it was stable then an electron would be permanently trapped in the state, but as we can see when a glow in the dark toy glows in the dark, eventually, over a period of time, electrons do manage to drop out of the metastable state and return to ground, so in this case we can say that ‘forbidden’ actually means ‘improbable’ but not impossible. It is interesting to note that the characteristic ‘lime green’ color of glow in the dark toys is an example of discrete indivisible quanta since it is this frequency of light which is produced by the difference between the energy of the metastable state and the ground state, since it is this frequency of light which the electron releases in the form of an energetic photon when the electron eventually returns to ground.

One of the principle reasons that a metastable state eventually decays and results in the emission of the photon (which is also the failure of the material to form a lasting solar battery, from our point of view) is because of thermal oscillations. This suggests that one way to convert phosphorescent material into a long lasting battery for energy storage would be to keep the material at close to absolute zero, since phosphorescence is a temperature dependant phenomenon. However, if we are looking to design a useful solar collector that is also its own solar battery, we would want a design that works at ambient temperatures, so this is a poor solution to our problem. Some small quanta of energy is exchanged between atoms in the form of heat. The process is random and sooner or later an electron loses enough energy so that its energy level exactly matches the difference between its elevated state and the ground state. Once this occurs the electron emits a photon of a specific frequency (as we can see by the greenish glow we see in glow in the dark toys, this frequency matching the energy difference between the elevated state of the electron and the ground state). The electron then falls back to its natural ground state, and the useful energy is lost having been emitted as a photon of light. For a power source we would want our device to emit useful electrons and not photons of light.

The Laser

It has occurred to me that given the similarities that exist between the device known as the laser and a phosphorescent solar cell, I am convinced that if we can design a device like a laser we should also be able to design an effective solar power source based upon phosphorescent materials.

There are some similarities as well as some differences between these two devices, and a study of the laser also gives us some clues as to how to go about creating a useful solar cell.

A laser is a light amplification device. When light or electricity is used to excite electrons in a gain medium, the electrons do a quantum jump to a short lived excited state, just as they do in phosphorescent material. The electrons in the laser gain medium then fall down to the equivalent of the metastable state. Light of a specific frequency is employed to cause the electron to release a matching photon and return to the ground state. There are now two photons with identical frequency, and for this reason laser light is described as being ‘coherent’. Typically mirrors are employed to bounced the light back and forth through the gain medium, which contributes to the amplification effect, as more electrons are excited and then encouraged to release more light at the specific frequency. The process is referred to as stimulated emission. Typically one of the mirrored surfaces is partially transparent, and so a coherent beam of laser light is allowed to escape from the cavity resonator. The light can increase exponentially within the cavity as excited electrons are stimulated and release coherent photons which continue to bounce (resonate) within the cavity contributing to the release of more coherent photons before eventually passing through the semitransparent mirror (the laser beam).

The Auger Effect

The Auger Effect refers to a form of stimulated emission, this time of electrons, rather than photons as in the case of the laser. When an electron is excited and jumps to a higher state, it leaves behind ‘an electron hole’. When the electron and the hole ‘recombine’ the results can either be the release of a photon, as is the case with the glow in the dark toy, or an electron can be ejected. If our purpose was to create a solar cell we would intend to stimulate the emission of electrons, rather than photons, and the Auger Effect leads us to consider a process of amplification similar to that which occurs in a laser, whereby electrons are excited by photons and jump to a higher quantum energy state, and then electrons within a magnetic field are employed to stimulate the cascading release of electrons, much as resonating photons bouncing off a mirrored surface are employed to stimulate the release of coherent photons.

Electrons can be found in what is referred to as the valence band, which corresponds to the ground state, or when an electron is excited it can move upward into what is referred to as the conduction band. No electrical current can flow if the electrons are found in the valence band, however when an excited electron achieves enough energy to reach the empty conduction band it can move freely and it leaves behind an electron hole in the valence band and electrical current can then flow. In a solar cell the process would involve ‘carrier generation’ (when an electron is excited to a higher energy level by a photon of light) which would then be followed by a ‘recombination event’. In normal phosphorescence the recombination event occurs when a photon of light of a certain frequency is released and the excited electron returns to ground state. However in a solar battery it would be required that the recombination event by the result of the Auger Effect and result in the ejection of an electron (referred to as an Auger Electron) rather than the emission of a photon. In Auger recombination when an electron and an electron hole recombine the energy is given to an electron in the upper conduction band, which then increases the energy of that electron. When a photon causes an electron to jump to a higher energy level (leaving behind an electron hole) the photon ceases to exist, and so in effect the energy of the photon has been transferred to an energetic electron. This is referred to as a transition without radiation, and it is this form of energy release (in the form of electrons rather than radiation in the form of photons) that is required in a functional solar cell. Just as the emissions of photons in laser can be caused by resonating photons, so Auger electrons can be emitted by energetic electrons.

Population Inversion and Emission

An electron can exist in a higher energy level excited state, or at the lower energy level ground state. When more electrons exist at a higher energy level state than the lower ground state, it is said that a population inversion has occurred. Because the higher level is more heavily populated than the ground state, emission rather than absorption is more likely to occur.

An electron remains trapped in a metastable state because no allowable quantum energy state exists which matches the difference between the energy level at the metastable state and the energy level at ground. The difference in energy between the excited state and the ground state can be widened by the application of an external magnetic field, such that when the difference in energy states is equal to one of the allowable quantum energy states, the electron is liberated from the energy trap and is free to emit energy, either as a photon, which would be undesirable for our purposes, or as an electron.

The Auger Effect can also be achieved by the introduction of energetic electrons, and thus it seems quite possible that the same magnetic field that widens the gap, liberating the trapped electron, could also be the magnetic field that employs electrons to achieve the desirable Auger Effect.

Double Helix Super Conducting Dipole Magnets

Magnets wound in the form of a double helix are now considered ideal for purposes requiring a magnetic super conductor (such as particle accelerators). The magnets produce a powerful field, but without the complicated and expensive windings typical of previous generations of super conducting magnets. They are cheap and easy to produce.

Currently such magnets are being employed by power utility companies for the purposes of load balancing. The magnets are employed in a super cooled cyrogenic environment where electrical resistance ceases to exist, which minimizes any possible loss of energy in the form of heat. Large amounts of power are then stored in the magnetic field generated by these magnets, and when a sudden surge of demand places a peak load on the power grid, the energy which had been trapped within the magnetic field is suddenly released onto the grid. The magnetic field is then recharged and ready for another sudden release of energy when the grid once again experiences a peak load.

It is obvious that if a functioning solar cell is to be constructed from phosphorescent material, it must incorporate a magnet in order to achieve the Auger Effect, and thus release electrons rather than photons.

What consideration of these facts reveals is that nature has supplied the solar collector and the utility companies are already employing methods to draw power from a magnetic field. Any electrons liberated from our solar cell would be carried by the magnetic field and then become useful energy. Therefore it becomes clear that in order to employ solar power all that is required is that a proper solar battery be developed, since the collector exists already in nature, and the technology required to use the electrons liberated into a magnetic field already exists.

Resonance and Damping – a thought experiment

One of the problems with nature’s solar cell is that it is subject to random thermal oscillations, which then allows energy to be transferred, lost and gained, and where sufficient thermal energy has been lost, an electron can reach the required energy level that matches the difference between the metastable state and the ground state, and the battery discharges. The second problem with nature’s solar cell, from out point of view, is that the battery discharges photons, rather than the useful electrons we require.

The first step in constructing a useful battery is to prevent the damn thing from leaking. If I had a lab and the money to spend on experimentation, I would be interested in testing the following hypothesis. Since it is thermal oscillations which is ruining my solar battery and causing leakage, it therefore makes sense to me to take matters into my own hands and employ resonance to prevent this from happening. Thermal oscillations are a form or resonance, and this cannot be avoided if a battery is to be constructed that will function at ambient temperatures rather than at temperatures close to absolute zero. Therefore, since there will be resonance, it seems reasonable to me that it should be a resonance chosen by me.. Therefore my hypothesis would be that I can supersede thermal oscillations by introducing a stronger resonance such that thermal oscillations are no longer of any consequence.

However there could be a problem here in that resonance can itself encourage the trapped electron to fall back to ground, and given that the resonance that I would be introducing would not be random, it is also possible that all I would accomplish would be to encourage an electron to fall to ground more quickly than might otherwise be the case.

With this thought in mind it has occurred to me that what I might want is to construct an energy trap for an energy trap, by introducing what is known as ‘critical damping’. Damping is the solution whenever there is undesired resonance. I want my trapped electrons to behave, and I want their behavior to be uniform. Therefore I want to introduce my own selected resonance and then to complete the trap I want to introduce ‘critical damping’.

Parallel RLC circuits

Let us assume that we were successful in preventing the emission of photons, and that what was once a metastable state has become a stable state. To complete the creation of the solar battery we need to employ a magnetic field and energetic electrons to mimic what happens in a laser, by using a small current to create an amplification effect and produce what would probably be a coherent flow of electrons.

Parallel RLC circuits are capable of producing resonance. When you tune in a radio station on a radio you are using a parallel RLC circuit. Such circuits are capable of producing resonance at extremely narrow bands (in this case the radio would be very difficult to tune, but the reception would excellent and interference free) or they are capable of producing resonance in broader bands of frequencies. The resonance we would require would depend upon the characteristics of the phosphorescent medium, just as the gain medium in a laser resonates at a particular frequency of light (the energy equivalent to the difference between the metastable state and the ground state, or in more modern four state lasers, the difference between the metastable state and a lower excited state which exists between the metastable state and the ground state).

Parallel RLC circuits create resonance by exploiting resistance, inductance, and capacitance. It is interesting to note that the double helix magnet is a solenoid, and thus has a natural inductance, and the capacitance is demonstrated by the fact that magnet is used as an energy storage device by power utilities. As for the resistance element, we would be using our magnets at ambient temperatures, rather than at super cooled, super conducting temperatures, and this naturally entails resistance, which is a normal feature of a parallel RLC circuit, and therefore we have just made a virtue out of a necessity.

When the time came to draw power off of our solar battery, we can imagine ‘tuning’ our RLC circuit such that the energy employed and the resonant frequency widens the energy gap between the metastable state and the ground state such that the trapped electron is liberated. Our device will require some capacitance (a small store of energy in the form of a capacitor) since we will need to introduce a small flow of energetic electrons into the magnetic field, which will be employed to liberate electrons (the Auger effect) much as photons are employed in a laser to liberate more photons at the selected frequency. Our device should be tunable so that the energy is produced at useable frequencies (for example I believe that in North America the useable frequency is 60 hertz). The liberated electrons will move into the magnetic field, much as they do in the load balancing super conducting magnets employed on the power grid, and from there the technology already exists to employ the electric current for useful purposes.

Design Characteristics of the Solar Cell

Our solar cell should be a circular disc, since it must conform to the shape of the magnetic field. This could be in the form of a hollow shell, composed of our phosphorescent medium, with an enclosed magnet inside. Given Einstein’s famous equation E=MC(2) we know that it is possible to store a massive quantity of electrical energy in a small quantity of matter, so we can assume that the size of the disk would be dictated by the requirements of the collector.

Questions for further study

I am convinced that it is feasible using current technology to construct a useful solar cell based upon what nature has already given us – phosphorescent medium. I plan to continue my research and hopefully flesh out my proposal further in the hopes of spurring the development of such an important device.

Some questions I would like to research further include the following.

For a given phosphorescent medium, does there exist an energy level which would be allowable for an electron, but would be forbidden to a photon. Here I am concerned in that we must achieve the Auger Effect, and that means that we must preclude the emission of photons. An electron must return to ground, and so therefore if there exists an energy level that is allowable to an electron and forbidden to a photon, it logically follows that we have just ensured that an electron will be emitted.

I would assume that for any given current there should follow a given amplified output. Therefore for a smaller input current there would be a corresponding amplified output current. This is required if we want to control the output. Therefore we could assume that voltage could be employed to control the output level. Is this correct?

If a phosphorescent medium is responsive to a broad spectrum (as seems to be the case with certain doped samples) then it seems possible to create a given output by resonance at only specific frequencies.

It would seem that given that nature has supplied the solar collector, and the utility companies employ technology to remove useful electrons from a magnetic field, the problem of creating a workable solar power supply comes down to solving just two problems.

The first is to find a way to transform a meta-stable state into a stable state while doing so at ambient temperatures. This will prevent the solar battery from leaking.
The second is to find a way to emit electrons rather than emitting the photons that are normally produced by a phosphorescent medium.

When these two problems are solved, we will have created a useful solar cell.
Now in regards to the second problem, electrons and photons can be described by the four quantum numbers. For example, one of the numbers is the measure of 'quantum spin', with an electron having spin 1/2 and a photon having spin 1. Pauli's Exclusion Principle states that no two 'fermions' (a class of quantum particles, such as the electron) can occupy the same quantum state, and so therefore the four quantum numbers must be different. All the available states of the fermion are described by these four quantum numbers. So in the case where only the spin numbers differ, and given that an electron can have spin +1/2 and spin -1/2 only two electrons would be allowed in the electron shell.

Therefore it seems logical that if out intention is to emit electrons into a surrounding magnetic field, it is required that the four quantum numbers describe an electron and not a photon. A photon can be absorbed by an electron and then an electron can emit a photon (as we can see when phosphorescent medium absorbs light and then emits the eerie greenish colored light we associate with certain inexpensive forms of phosphorescence incorporated into toys). Therefore, given that there is no hard line separating photons and electrons, and given that an electron is described by four quantum numbers, and a photon is described by four quantum numbers, therefore to cause out solar collector to emit electrons we are required to ensure that the four quantum numbers that describe the emission describe an electron rather than a photon.

I have an hypothesis which intuition suggests makes good sense. There exists a resonant frequency such that it would be possible to match the energy level of an electron trapped in a metastable state, creating the resonance (and the critical damping) described above, while at the same time not creating interference with the absorption of photons by the phosphorescent medium, since both the ground state and the higher excited state are energy levels which differ from the electron trapped in the metastable state.

Given that we only have these two problems to solve I remain fully convinced that creating a powerful new solar energy source is within the reach of our current technology and our current understanding of quantum physics. This project is doable.