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Nanowires Increase Efficiency of Solar Cells

Solar energy is a power source that has long been sought to implement for wide spread consumer use worldwide. The factor currently inhibiting its global integration into the power grid is attributed to its high production and maintenance cost. Although solar power is one of the truest renewable energy sources its integration in the modern power grid has been a slow process to say the least. All of this could change soon however due to research being conducted by scientists in Denmark and Switzerland from the Nano-Science Center and Ecole Polytechnique Federale de Lausanne.

The latest developments in solar technology have come about from the use of a type of nanowire which can concentrate light an estimated 15 times higher than normal sun light. These nanowires contain a light absorption property that enables them to concentrate the amount of sunlight absorbed by the silicon materials used in solar cells. Peter Krogstrup PhD published an article about the possibilities of the application of these nanowires to generate a greater amount of solar energy in the journal of “Nature Photonics”.

The nanotechnology used in this research uses crystals in a cylinder like structure approximately 1/10,000 of a human hair in diameter to concentrate light. Not only can this be used in the development of new high efficiency solar cells but this technology is also expected to be applied in electronics and for the development of quantum computers.

The principles behind the use of nanowire crystals is that the diameter of the wire is smaller than the wavelength of sun light which causes it to bounce and resonate in and around the crystals thus concentrating the amount of light that is impacted on the areas of silicon that convert this into energy. This can achieve a concentration of sun light up to 15 times higher than what was previously thought possible through the “Shockley-Queisser Limit”, also referred to as detailed balance limit, which is defined by physics as a theoretical maximum limit for solar efficiency.

The Shockley-Queisser Limit was devised to measure the efficiency of single p-n junction solar cells with a specific band gap defining an efficiency of about 33.7% although most consumer solar cells use mono-crystalline cells which are only 22% efficient due to sunlight being reflected from the surface layer. The p-n junction model refers to a solar cell which uses p-type silicon on the anode connection and n-type silicon on the cathode connection for the crystal semiconductor.

Although the actual percentage of concentration may seem relatively small, it is important to understand that the previously described maximum solar efficiency limit by William Shockley and Hans Queisser in 1961 has been perhaps one of the single most fundamental developments in solar technology. The discovery of nanowire crystal technology has broken the barriers of what physicists previously perceived as a landmark in solar cell technology by increasing the once thought theoretical limit of solar efficiency. The leading researcher for this technology comes from Peter Krogstrup who has recently received his PhD from the Niels Bohr Institute, University of Copenhagen who believes despite the excitement caused by this research the actual implementation of this discovery for international solar power production will still take several years of research and development.

Posted on: April 16th, 2013 by Anttu Lein | Physics

Stealth Technology: Sound Cloaks

Stealth Technology

Cloaking is a feat that has been a predominant area of research for military purposes to give our armed forces a decisive advantage over our opposition. The basic philosophy of developing cloaking technology involves figuring out how to minimize the scatter of waves be it light, sound or radio when they strike an object which creates a perceived signal. Objects that we are able to see are visible because of the light waves bouncing off them thus creating the visible world around us which holds similarly true for sound waves.

Research conducted by an electrical engineer, Jose Sanchez-Dehesa, out of the Polytechnic Institute of Valencia has led to the discovery of a new method to minimize the way sound waves scatter when they hit an object. Development of a plastic shell made up of a number of layer of rings has led to the discovery that manipulating the way sound waves scatter can cause noise cancellation similar to the technology used in noise canceling headphones which emits a sound to cancel out what is heard. The application of this development is the first successfully cloaked three dimensional object from sound waves.

The plastic shell is made up of 60 rings encases a sphere which utilizes the rings and their angles in a precise format calculated by a computer algorithm to achieve invisibility from sound waves. Although developed out of fairly primitive materials, the application of this technology has been precisely calibrated to achieve what many consider to be a masterpiece of stealth capability. Further development of the concepts outlined in this research is expected to be applied in sonar blocking technology for military ships and submarines for the Navy as well as minimizing sound pollution in metropolitan areas.

Previously research being conducted in invisible technology has used sophisticated synthetic materials to attempt to steer light and sound waves around an object, however the drawback has always been the cost and development time necessary to achieve this is largely unrealistic to mass produce. The technology developed by Sanchez-Dehesa uses a much simpler method of disguising sound using the reflection of audio waves within the rings to cancel each other out. The experiment conducted used a sphere encased in the ring device suspended from the ceiling in an echo free chamber while various levels of sound were emitted with a sensor behind the object to detect its presence. Although most sound waves projected were detectable, at 8.55 kilohertz (high pitch frequency) the sphere was undetectable by the sensors behind it.

Despite being in its early stages of development, the U.S. Office of Naval Research has already taken notice of this research being conducted out of Spain as it has provided funding for other programs to create technology to achieve sonar invisibility. The current technology was developed specifically for the sphere used in the experiment by using an algorithm to map the predicted sound trajectory before developing this device. This means that currently every object this is used on needs a custom design to achieve the same level of disguise which unfortunately does not look very promising for use in submarines in its current state. City planners on the other hand are very interested in the possible use of this research to develop better technology to block sound pollution caused by highways in residential areas.

Posted on: April 12th, 2013 by Anttu Lein | Technology

Synthetic Biology: Programming Life

Biology is a subject most are familiar with through their studies in grade school however revolutions in the way biologists utilize the application of their knowledge of living systems can potentially change the course of humans as well as other species. One of the growing trends in biological studies involves the application of synthetic biology to alter the genetic function of simple organisms. Synthetic biologists have already begun a process of genetic manipulation to alter what bacteria, yeast and other microorganisms produce with a primary focus on the production of fuel sources and medicinal chemicals.

Before we explore this subject further, many may wonder; what is synthetic biology? Synthetic biology is a combination of biology, engineering and chemistry with a focus on using the processes of bioengineering to create a result useful for humanity. This combination of science and technology is currently being used for the treatment of diseases and in research towards energy production needs.

How can a living organism be altered by scientists?

Much like the technological revolution of the digital age through the use of binary language, biologists have discovered that genetic coding can be manipulated through a variety of methods. In fact this process is a naturally occurring and ongoing process for organisms through genetic variation and evolution. Through the use of genetic manipulation biologists have discovered that they can enhance natural genetic engineering and alter the function and production of organisms. These benefits are expected to impact developments in biofuels and medicine. Advanced research is even being used to reprogram the human immune system to fight diseases such as cancer which has already been tested in a small number of terminally ill patients with astounding results.

Research being conducted out of UC Berkley in bioengineering has produced a pharmaceutical drug called artemsinin to combat malaria from a byproduct of yeast which is expected to be the first product synthesized from work in synthetic biology to reach a consumer market. Further research with engineering yeast is being conducted for the production of biofuels from microbes. New approaches are being devised to utilized an estimated billion tons of biomass which is currently considered to be waste materials along with producing “green” or “clean tech” alternatives to petroleum products. The integration of biofuels has been an ongoing process to accommodate the needs of the growing world population while enhancing the production of clean technology to a rate which is cost efficient for mass production.

Microbes are the leading focus of synthetic biology which is expected to achieve results in improving plant health and prevention of diseases to achieve a state of agricultural stability in the modern world with an ever growing human population. Despite the potential benefits in this type of research a debate continues to ensue about the ethics of manipulating living organisms to benefit the human species. Many believe that altering the evolutionary course of an organism through bioengineering can have dramatic effects in the future and is perceived as “playing God”. On the other side of these opinions some scientist point out that with the threat of climate change through human induced environment alterations needs dramatic measure to restore a suitable equilibrium to the compounding factors of the Earth’s changing climate.

Diagram of the Bioengineering Process

Posted on: March 29th, 2013 by Anttu Lein | Biotechnology

How Does Solar Energy Work?

What is solar energy?

Sunlight is a source of food and energy to almost all forms of plant life on the Earth. Ancient humans utilized this knowledge in architecture to enhance heating and lighting in buildings. With advancements in science and technology the question was posed, “how do humans harness the full potential energy from the sun?” This question was answered by Alexandre Edmond Becquerel in 1839 when he discovered the photovoltaic system which was later refined by Russell Ohl in 1941 to produce the first solar cell which is employed to this day to produce electricity from the sun’s rays.

How does solar power work?

Capturing solar power is a process which utilizes the heat and radiant light emitted from the sun’s rays to generate electricity. But how is energy created from light? When the photon particles which make up light strike an object it produces energy which can be felt in the form of heat. Certain compounds of elements let off electrons when sunlight strikes while other elements accept electrons when light strikes them. It was discovered that combining both of these types of compounds together could create a system that would conduct an electrical current through a conductor, thus capturing electricity.

How is solar energy captured?

The most commonly thought of type of solar energy is the photovoltaic system (or PV system) which utilizes panels of silicon or another similar material contained within a layer of tempered glass for protection. Further advancements have allowed these PV systems to take on a variety of practical applications to allow the consumer a wider variety of choices on how this technology can be employed effectively. These are known as PV modules, configurations, panels and cells which allow a customized energy solution for the right environment.

Solar Power Efficiency

Although the sustainability factor of solar energy is in theory one of the most viable, in application capturing electricity through solar rays is a costly endeavor due to the materials required to capture the electron transference. So how is the cost of energy production measured? The price of power is measured by using the cost of kilowatt per hour (kWh). Standard coal power is approximated to cost about 10 cents per kilowatt per hour, while solar power is at approximately 25 cents per kilowatt per hour. These costs of course are calculated by the life cycle of the solar system generating electricity.

Solar Incentives

There are three major ways in which solar power can be incentivized to allow it to flourish despite the costly expenses a user can expect to pay over its lifetime of use.

Government solar power incentives

Governments that offer solar power incentives for installation and usage is one of the most effective ways to produce a demand for the energy source. Human nature is not to be wasteful by default, however we sometimes waste limited resources to produce power for our day to day lives. Incentive programs provided by the government can help make its citizens both feel productive and receive a reward for utilizing a cleaner renewable power source rather than fossil fuels.

Electricity grid integration

Integrating a solar energy system, whether on a home or business, with the power grid run by the city or state is another good way in provide an incentive for more consumers to get on board with solar power. This allows the consumer to produce the electricity needed to cut out the need of fossil fuel energy and allows the consumer to sell any unused power to the electric companies for reuse among other areas of need. This allows the consumer to recoup some of the losses spent on installation along with generating typically a small source of income all while providing a renewable infrastructure to produce power for others.

Cut costs on current electricity bills

Finally, cutting the cost of your electricity bill is another benefit of employing solar energy in personal and business environments. Combining the power grid integration and government incentive programs allows many individuals to dramatically reduce their cost of electricity usage with the added benefit of improving the environment.

Overall it is common knowledge that integration of solar power can dramatically affect our current environmental state of well being along with creating a state of mind within the public that renewable energy is an excellent alternative to fossil fuels. Despite the benefits of utilizing the power of the sun, it is a costly endeavor which is currently creating a halt in the widespread implementation of this renewable power source. In the coming years we expect to see advancements in this technology to allow solar energy to become more cost effective and energy efficient, thus allowing it into a permanent part of our nation’s infrastructure to produce clean energy for our future.

Information referenced from http://www.getsolar.com/why_solar_types-of-solar-power.php

Posted on: August 24th, 2012 by Anttu Lein | Energy

How Does Geothermal Energy Work?

What is geothermal energy?

Geothermal energy is a process which utilizes thermal energy (heat energy) of the Earth to power turbines for the production of electricity on the power grid. This technology can be used on a variety of scales for national production of electricity or simply to provide additional power to a home on a smaller scale. This energy source is considered to be a renewable energy source since the Earth constantly produces heat internally through the circulation of magma and increased pressure in certain areas.

Where does the Earth’s thermal energy come from?

Thermal energy on our planet is produced initially at the Earth’s core where intense pressure forces rocks to heat up and melt creating magma. Magma, naturally lighter than the solid rocks contained in the layers above the core, finds every resource available to attempt to escape which creates thermal hotspots that can lead to formations of hot springs or volcanoes. Through the development of technology, this energy can be harnessed in the same ways that locomotive technology was created by using steam to power an engine.

How does geothermal power work?

When building a geothermal power plant, it is essential to first either find or create what is called a geothermal well. This is a pocket of water located in a hotspot within the earth that uses the natural thermal energy created to cause the heated water to evaporate or flow up a pipe to the power plant. From this stage there are three distinct processes which can be used to capture the energy to produce electricity. Both processes use a turbine which will be powered by the movement of particles heated from the geothermal well. The most common process used to mass produce electricity from geothermal energy is in the binary cycle power plant.

How is geothermal energy captured?

A binary cycle power plant is one which utilizes the geothermal energy available in the Earth to power turbines which in turn create electricity through a process known as hydrothermal convection. Hydrothermal convection is the process of which water is heated to a boiling point and is pushed towards the Earth’s surface from a geothermal well. There are three distinct processes currently in use by 28 nations in the world to produce power from thermal energy captured from the Earth. Currently the countries that use this energy technology are the United States, Philippines, Indonesia, Mexico, Ital, New Zealand, Iceland, Japan, El Salvador, Kenya, Costa Rica, Turkey, Nicaragua, Russia, Papua-New Guinea, Guatemala, Portugal, China, France, Ethiopia, Germany, Austria, Australia and Thailand. The three main ways in which energy can be captured are through dry steam, flash steam, and the binary cycle power plant.

Dry steam technology:

Dry steam technology uses water directly from the hydrothermal convection process to flow upwards into a pump which in turn uses the water to power a turbine that creates electricity. The steam is pumped from the heated well into a turbine system where it is used to spin the turbine blades and produce electricity. After the steam is used to power the turbine it is returned to the injection well where it is cooled back to its liquid state where it can be pumped back into the geothermal well for reuse in the cycle of creating electricity.

Flash steam technology:

Flash steam technology uses the same basic process as dry steam with the exception that the water it’s self is not used to power the turbines. The water gathered from the geothermal well is used only as a heating source the heat to evaporate a secondary fluid, one which must have a boiling point less than water, typically butane or pentane hydrocarbon. The secondary fluid is responsible for powering the turbines and is then sent through a cooling area which is made up of either cold air or cold water circulation systems to change it back to a fluid.

Binary cycle power plant:

A binary cycle plant uses a combination of both of the processes above to more efficiently capture the potential from the secondary agent for power. Hot water travels through a heat exchange which super heats the butane or pentane hydrocarbon causing it to spin the turbine to produce electricity. The working fluid is then passed through a cooling system to return it back to its original liquid state. Heated water then flows down into the injection well where it will be cycled back into the geothermal well for further use.

Sources for this article http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-geothermal-energy-works.html.

Posted on: August 21st, 2012 by Anttu Lein | Energy

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