Fix it when the Sun Shines - Photovoltaics

In our last post we expressed the need to find an energy resource which could solve our energy problems not only by providing power but being clean as well. And some say the obvious answer is the sun. And here is a good reason for this; if we can utilize 0.1% of the total energy absorbed by the earth over the course of a year from the sun, we can produce enough energy to eclipse the current energy generation by 10 times! The energy from the sun is mapped in the figure below.

Solar energy has been harnessed by humans since antient times and the technology is still evolving. Other renewable resources including wind, wave power, hydroelectricity and biomass wich are most of the renewable energy resources on the planet are secondary derivatives of the sun. A single post will definately not be enough for this, so here to a sunny summer.

Photovoltaic Cells

Photovoltaic cells translate solar energy to electrical energy because of the photovoltaic effect. The photons (packets of energy) in sunlight include energy corresponding to the diverse wavelengths of sunlight. When light strikes upon a photovoltaic cell these photons may pass through, be reflected or absorbed by the panel. On absorption of photons the energy contained in the photon is redirected to an electron contained in the atom of the semiconductor material the photovoltaic cell is made of.

General photovoltaic cells contain two layers of silicon wafers doped with phosphorous and boron. The layer doped with phosphorus (called the n-Layer) contains excess free electrons and the layer doped with boron has a tendency to attract electrons (called the p-Layer). Though neutral individually when stacked on top of each other a “p-n junction” is formed due to transfer of electron from the “n-Layer” to the “p-Layer” creating a barrier to prevent more electrons from moving between the layers and also reversing their polarity. This leads to poles, negative for the “n-Layer” and positive for the “p-Layer”. When placed under the sun photons in light strikes electrons in the “p-n junction”, energizing them and knocking out the atoms, thus attracting the electrons to the positive n-layer and repelled by the negative “p-layer” and hence generating electricity.

The simplest photovoltaic cell can produce much less energy as it does not fully utilize the entire spectrum of light. Photovoltaic cells are distinguished between each other by the type of the crystal used. As can be seen from the table below, Multi-junction cells boast the highest efficiencies in photovoltaic technology and are best with concentrators, however due to their expense Multi-junction are mostly used in aerospace operations.

Multi-junction photovoltaic cells

Multi-junction photovoltaic cells offer high-performance scientific development passageway for low cost electricity generated by concentrating sunlight. These photovoltaic cells consist of several thin films/layers that allow them to confine more solar spectrum to translate to electrical power. Semiconductors have a distinguishing band gap energy that allows absorption of light (electromagnetic radiation) very efficiently for a certain colour (spectrum portion). These semiconductors are needed to be cautiously selected to take up most of the spectrum of sunlight, leading to higher electricity generation.

Multi-junction PV cells use numerous layers of PV films, made of differing alloys of III–V semiconductor material. The band gap of each layer can be adjusted to allow the absorption of a specific band of electromagnetic radiation from the sun. However, it should be ensured that each layer is lattice matched to the other. The Layers are aligned optically in series with the largest band gap material on top. The top layer receives entire range, the photons with band gap higher than the layer are absorbed and the rest is channelled through to the lower layers.

The best know and available Multi-junction cells for terrestrial use are produced by “Spectrolab” called Ultra Triple Junction (UTJ) solar cells consisting of In0.56Ga0.44P / In0.08Ga0.92As / Ge layers shown in the figure above, on test have shown to provide efficiency of 40.7% with a concentration level of 240 suns and a general efficiency of 24.3 %.

Sources:

Wikipedia, need.org, Us Department of Energy, solarserver.de, Spectrolab

- Energy Engineers to the rescue

- OSSA

What the Future Demands from an Engineer

Through our years of development we have reached a stage where we are threatened by our own ingenuity in the past. It may be said that, it was the engineers who doomed the world with the inventions why should they should be trusted again? Well you know what, you have no other choice.

We argue as to why we can't go back to the way we had been living before, downgrade ourselves to save the planet, but as far as I know, we are not good for settling for less, I myself am not. We enjoy the convenience the development has brought about, and in many cases we can't live without them, we have been molded into this system as such. However, its not only the matter of convenience. We all acknowledge that we are living in a dying world, we have reached a stage where we might have to go back to being cavemen to actually save the planet. We are not only looking at retracing our footsteps but reversing the effects on the planet. To explain in the form of an example, we have released so much carbon-dioxide into the atmosphere, its time to suck it in.

Area of focus: ENERGY

Anything we do, we need energy; this is one of those things that has become an intricate part of our lives and we cannot do without. As technology advances, so does our demand for energy as can be seen in the figure below. So what is the problem? just build power plants, and the problem is solved? Not quite.

The source of energy is a big concern, though oil is a stable industry it is running out, so is gas and causing harm to the environment, nuclear energy is highly unstable, renewable energy is underdeveloped, weather dependent. The need is hence for a substitute for oil for the generation of electricity and for transport. We have the sources, but do we have the technologies to tap into these sources?

Energy utilization defines all the valuable requirements for life in today's world; food, the air we breathe, and the most precious, energy also plays and will play a huge role in is for the production of water in most parts of the world. There are very few sources of fresh water left and in arid areas (like deserts) desalination is required which uses up a lot of energy. The figure below shows the water resource distribution around the world.

Sources in focus: ALTERNATIVE ENERGY SOURCES

Alternative energy sources defines any source of usable energy that can be used to replace fuel sources in this case Petroleum without its undesired consequences. They can be further categorized into Renewable (which utilize sources such as sun, wind, water and other naturally available energy sources), Nuclear (including Fission, Fusion), Hydrogen and Fuel Cell technologies. These technologies are relatively, and in some cases far cleaner, than the conventional technologies. However they are riddled with their own problems.

Over the course of our posts we shall try to highlight these technologies, the problems associated with these technologies and showcase the engineering solutions proposed and being worked on to solve these problems and may be leave a few suggestions of our own.

Photos:
whyfiles.org ,eia.gov,islamicity.com

- Energy Engineers to the rescue
- OSSA

Thermal Energy!

Thermal energy is generated and measured by heat of any kind is due to the increased activity or the speed of molecules in a substance, which in turn causes temperature causes rise accordingly. There are many natural sources of thermal energy on the earth, making it an important component of alternative energies.

To explain the laws of thermodynamics, that energy can be exchanged to another in the form of heat from a physical object. For example, putting fire under a pot with water, the water is heating up as a result of the increased molecular motion. In this way, the heat or thermal energy, the fire is partially transferred to the water.

Understanding the principles of thermodynamics has allowed people to use to create the natural sources of heat, thermal energy from a variety of sources. The sun, ocean and geothermal sources such as geysers and volcanoes, all sources of thermal energy. As an exhausted people, sustainable forms of alternative energy instead of fossil resources, such as try again, much attention has focused on improving the methods of harnessing the heat energy to the power of human activity.


Solar thermal power plants is one of the most common forms of thermal energy. Although Assembly solar energy is available only when the sun is visible in the sky, scientists have many different options for storage and use of developed included the performance of solar systems. On a small plane, a man his pool by low-temperature ducts to heat in or around the water. By absorbing sunlight and distribute it on the water, the temperature throughout the day and even after the sun has risen. Solar panels, evaporative pools and other advanced systems can perform this function on a much more widespread level, which saved enough energy to run a factory or city on solar thermal.

The Earth is around a molten core of the incredible heat that built up substantially reduced, as it reaches the surface, or crust level. But is generated by the use of some of the heat below the surface of the planet, humans can extract enormous amounts of energy. The easiest way is to do so by geothermal energy sources such as geysers, or at the boundaries of tectonic plates. Geothermal wells pump out energy in the form of hot water or steam can be converted into usable energy, or simply be used directly.

Thermal energy is an awesome force that is just beginning to be understood. to focus through the creation of new devices and methods of storing and transporting of course creates thermal energy, the human dependency on non-sustainable forms of energy. Thanks to the power of heat, hot baths, boiled water and thermally driven cities are possible.

source:wisegeek.com

Sound Energy!

Sound is produced, the energy of sound waves as they travel through a particular medium. Sound waves cause vibrations of the pressure that lead to a certain degree of condensation and rarefaction in the media, through which the sound waves. Sound energy is also a form of mechanical energy, it is not contained in discrete particles and is not to cause a chemical change you, but is purely to pressure its vibrations that you want. Sound energy is used in general non-electric energy or for other human energy needs since the amount of energy that can be made from clay, is quite small.




Energy is the amount of work by a given power system, object, or anything else can be done in a position to perform work. The work is simply the ability to cause changes in defining a system that can include everything from a change in the position to a change in heat energy. The amount of work that can be performed by common every day sounds, is quite small, so that no sound is often thought of in terms of the energy it contains. Sound energy is there, however, change sound waves cause a vibration, even if such changes small.


Instead of measuring sound in typical units of energy such as joules, tend scientists and others measure it in terms of pressure and intensity with units such as Pascal and decibels. Sound measurements are, by their very nature, compared to other sounds that cause more or less pressure. Normally, the tone in regard to the way it is perceived to be of healthy human ears described. A sound that is produced from 100 Pascal pressure at an intensity of about 135 decibels, for example, commonly described as the pain threshold. There is enough pressure and intensity, which are often combined in the common term "loudness" to cause physical pain.

Sound energy is closely related to the ability of the human ear to perceive sound similar. The wide outer region of the ear is maximized in order to collect sound waves. Sound energy is amplified and passed through the outer ear, striking the eardrum, which transmits sound to the inner ear. Auditory nerve to fire the special vibrations of sound waves in the inner ear, which refer to such things as pitch and loudness of the sound. The ear is in an optimal way to interpret the energy in the form of sound vibrations set.

Ethanol Production Industry

Do you know who is the largest ethanol producer in the world? America? Some country in Europe? South Africa? It actually depends on the geographical area that you are speaking about. Let's check out who they are...

Largest ethanol producer in the world

Brazil is currently the world's leader in ethanol production. Because of government subsidies, large sugarcane crops, and high sales taxes on gasoline, Brazil has built a profitable national ethanol industry. Sugarcane is grown in the country as the climate presents perfect conditions for its cultivation and production. It converts very easily to ethanol, and provides Brazil with huge supplies of ethanol.

Largest producer of ethanol in the U.S.

The largest producer of ethanol in the U.S. is a company that many of us have probably never heard of. The company is Archer Daniels Midland. ADM is a company that is an agricultural giant in the United States, and has decades of experience. They have a vast network of railcars, trucks, storage facilities, and barges that are capable of delivering high-grade ethanol.

Hmmm... there are actually more to discuss and more to share about the Ethanol Producers. It's tough to share all those technical, economical and other related information about ethanol producers in a short blog post like this. To have a clearer and precise information sharing on ethanol business, I would like to recommend Ethanol Producer magazine.

The magazine is known throughout the ethanol industry for its authoritative plant construction lists, compelling profiles and engaging features on production, research, science, technology, equipment, environmental and safety compliance, marketing, policy and industry events. Most importantly it is free... Yep..no cost at all. However, I'm sorry to say only those in US, Canada and Mexico is eligible to request for it.

To get the Ethanol Producer magazine, click here.