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Ballooning to make solar energy viable
Why stradivarius violins are best
Prof Yash
Pal I’m an avid reader of your weekly column in The Tribune. Many a time you solve the scientific queries of the common man. I’m a brick kiln owner and I have an interesting question regarding my trade. A brick kiln is semi-circular in shape. Unbaked earthen bricks are stacked in the vessel of a traditional brick kiln and then brick kiln is fired from one side. |
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Ballooning to make solar energy viable
With sky-rocketing energy prices and mounting fear of the climate change due to burning of fossil fuels, scientists are showing immense interest in renewable energy sources, especially the solar energy, which is zero pollution and called green energy. There is no shortage of sunny days on earth surface but the problem is of the space, which the solar panels need to harness solar energy. These panels require a huge land cover for this purpose.
Israel’s Technion Institute of Technology has developed a technology, in which the solar panels would be put at some height to convert solar energy into electricity. A number of 3-meter helium-filled balloons with 0.2mm-thin solar panels on them are to be stationed at a height of few meters in the atmosphere with each balloon capable of producing one kilowatt of energy, which is enough to operate a washing machine and a drier. This technology reduces the cost drastically and the harnessing of solar power becomes economically viable and is pollution free. In traditional solar cells, one kilowatt of energy requires area coverage of 25 square meters and an investment of around $10,000; much higher than $4,000 from a solar balloon. If the ground is already being used for some another purpose or there were no land, then, the balloon can be tethered to any part at the top of the building and even on the ship in the sea. They can stay afloat in air for up to a year before they need to be replaced or reinflated. They are lined with solar panels, about 0.2 mm (0.008 inches) thick, and a three-meter balloon weighs about 2.5 kg. The earth’s surface receives about 89 petawatts (1 petawatts = 1015 watts) of sunlight annually and we are able to use only 15 terawatts (1 terawatts = 1012 watts) of average power per year, a meagre part of solar energy. Thus, there is a plenty of room for expansion of solar energy. In years, however, the solar-energy market has been hampered by the shortage in supply of refined silicon, the substance needed for solar-cell fabrication. Keeping in view its perennial availability, the harnessing of the solar energy for power is highly promising. According to Dr. Eric B. Cummings, the founder of CoolEarth Solar, based in Livermore, California, the balloon technology could make solar farming economically competitive within three years by making solar cheaper than coal and allowing farmers to become net suppliers of electricity. With the use of this technology, the cost of solar electricity is going to reduce by a factor of 25, therefore, making it cheaper than coal and other non-renewable sources. The CoolEarth Solar technology makes use of a string of balloons to concentrate and capture the sun’s energy without occupying valuable land or using large amounts of silicon. These balloons are made from durable material used in meteorological balloons and filled with helium and insulated on the inside by silicon to reduce leaks. These inflatable concentrators gather light and focus it on the photo- voltaic cells, increasing the energy impacting the cells many times over. The photo-voltaic cells convert light energy into electricity. A series of these concentrators are suspended on support and control cables stretched between poles. By suspending the concentrators in such a way, vast areas of land can be easily converted for solar-energy production with least environmental impact. The ground beneath these concentrators remains free for farming and other purposes. This design costs 400 times less per collected area than conventional mirrors. Further, it can withstand winds of speed 100 miles per hour and can protect the mirror surface and receiver from rain, insects, dirt and the other issues that can significantly reduce the productivity of solar cells. The low maintenance and replacement costs of the system will significantly reduce the cost of solar energy from the current price of around $4 per watt of installed capacity to levels where it is viable and competes directly with fossil fuel-based energy sources. The system is going to be beneficial in rural India with the abundance of area that is easy to access and maintain the ease of setting up large power plants and less resistance from residents associations. According to Gopal Shanker, president of Récolte Energy, a green-energy consultancy firm in Napa, California, the system can also offer immense potential for the wine industry. The system is going to work well for the wine industry, since it is off-the-ground and wouldn’t obstruct sun light to the grapes. The world is racing to find renewable energy sources to replace fossil fuels, and entrepreneurs are competing for a slice of a clean energy market. Giant solar energy balloons floating high in the air are going to be the cheapest way to provide electricity to areas lacking the land and infrastructure needed for traditional power systems. The balloon technology has no carbon footprint or negative impact on the environment. Helium gas in the balloon is a naturally occurring gas and environment-friendly. This technology saves land from being occupied as well as resources vis-à-vis the glass and metals used in ground-based solar energy systems. The land-based solar panels, usually, point only in one direction and their efficacy are affected by the sun’s position in the sky and can be obscured by taller structures. In the new system, the balloons’ circular shape ensures that they always receive direct sunlight. If this system can’t act as a main power system, but surely, it can be an auxiliary system of power supply. Since the balloons are easy to transport, require little infrastructure and can be inflated on site, the system could be used for emergency power in regions blacked out by natural disasters. The promice is to deliver solar power at 29-cent-per-watt. Hence, the balloon technology has bright future in areas of low-value land as it can be used for solar farms in the Sun Belt. The writer is Associate Professor (Physics) in the Department of Chemistry & Physics, CCSHAU,
Hisar
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Why stradivarius violins are best
Scientists compared five antique violins made by the Cremonese masters Antonio Stradivari and Giuseppe Guarneri Del Gesu with seven modern-day instruments by placing them in a medical scanner that could accurately gauge the density of the two wooden plates that make up the top and the back of the body. They found that, overall, the density of the two groups of violins was the same, but what differed significantly was that the two plates of the older instruments had a more uniform density compared to the more inconsistent densities of the modern plates. The top plate of a violin is usually made of spruce and the back of maple. The scientists believe that the homogenous density of the Cremonese violins gives them the edge in terms of stiffness and sound-damping characteristics, which both help to produce superior musical notes. The classical violins made by the two Cremonese masters have become the benchmark against which the sound of all other violins are compared. Yet by general consensus no instrument maker since that time has been able to replicate the sound quality of those early violins, said Berend Stoel of Leiden University in the Netherlands. “The vibration and sound-radiation characteristics of a violin are determined by an instrument’s geometry and the material properties of the wood. New test methods allow the non-destructive examination of one of the key material properties, the wood density, at the growth ring level of detail,” Dr Stoel said. The CT scanner used by the scientists is normally employed to study the density of the tissue within a patient’s lungs using X-rays. However, Dr Stoel, working with a professional instrument-maker, Terry Borman, of Fayetteville in Arkansas, was able to build up a picture of a violin’s density variations using CT scans, which carried no risk to the valuable instruments. “Wood density is difficult and invasive to measure directly, as an isolated part of the instrument, wrapped in a waterproof container, must be immersed in water to estimate its volume, and its density is calculated by dividing its weight by this volume,” Dr Stoel said. On top of this, this conventional approach to measuring wood density is not able to measure variations within a single plate n which appears to be the difference that may explain the quality of the antique instruments. Dr Stoel, whose study is published in the online journal Public Library of Science, said the density variations within the wood are caused by the type of wood growth. Early growth in spring is less dense than summer growth, and the antique instruments appear to have a more balanced mix of early and late growth. “Early growth wood is primarily responsible for water transport and thus is more porous and less dense than late growth wood, which plays more of a structural support role of much more closely packed tracheids (the light and dark grain lines of wood),” he said. — The Independent
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This Universe
I’m an avid reader of your weekly column in
The Tribune. Many a time you solve the scientific queries of the common man. I’m a brick kiln owner and I have an interesting question
regarding my trade. A brick kiln is semi-circular in shape. Unbaked earthen bricks are stacked in the vessel of a traditional brick kiln and then brick kiln is fired from one side. In all the brick kilns fire’s movement is anticlockwise. The fire moves forward in anticlockwise mode in the vessel and unbaked earthen bricks are continuously filled at one opening and baked bricks are removed from other side when fire has gone quite forward and bricks are cool enough to be removed by manually by labourers. I have asked many brick kiln owners, but no one was able to give any scientific answer as to why movement of fire has to be anticlockwise? I’ve also noticed that movement of athletes in a track is also anticlockwise. Is there any relation between movement of fire in a brick kiln and that of athletes in a track? Incidentally a vessel of brick kiln is semi circular in shape almost resembling the shape of a track of a
stadium. Thank you for sharing your curiosity. I wanted to write to you right away but I am not so sure about my explanation. You must know that the cyclones in the Northern Hemisphere spin in anticlockwise direction while in the Southern Hemisphere the spin direction is clockwise. This fact is very well explained due to the rotation of the earth which leads to a force called the Coriolis force. Therefore the temptation was to give this explanation for your observation. However, I was hesitant because I am not very familiar with the construction details. Do you have some friends who have set up kilns in South Africa or Australia? The explanation that I have given above would suggest that for them the fire would move in clockwise direction! Maybe you should yourself build a kiln in one of those areas. Your reference to similarity with the direction in which the athletes run cannot be any thing but a coincidence. No physical connection can be thought of for this similarity. There is however a similar folklore about the direction in which the water spins when the drain plug is pulled out of a sink filled with water. The direction of the spin is easily seen if a few tea leaves are spread on it. Some teachers who had already learnt about the Coriolis force told the students about testing its validity through this experiment. It is not surprising that most students cofirmed this hypothesis. When the direction of spin was found to be opposite they called it an experimental error or defect in the drain pipe or shape of the sink! The long and short of this story is that there are too many disturbances in the sink experiment; unless it is done with great deal of care the result would be random. I keep wondering whether this is also true of your kiln experiment. Perhaps some more data, with the help of lot of readers would establish or disprove this explanation. Let me again thank you for bringing it to our notice.
Recently there has been news in the media supported by inputs from NASA that the polarity of the magnetic field of the sun is changing that would lead to massive earthquakes, flood and other calamities causing extinction of life on our planet in the year 2012. I would like to knowyour expert comments. It is true that the magnetic field of the sun has flipped. But this is nothing new, or unexpected. Such a flip occurs every 11 years when the Sun reaches the maximum of solar activity cycle. Therefore this should not be taken as a warning for horrible things happening on the earth. There are always some effects but nothing cataclysmic. Readers wanting to ask Prof Yash Pal a question can e-mail him at
palyash.pal@gmail. com |
They are said to produce unparalleled sound quality. Until now, however, no one has been able to explain why 300-year-old Stradivarius violins have A study has found that the secret may be explained by the consistent density of the two wooden panels used to make its body, rather than anything to do with the instrument’s overall contours, varnish, angle of the neck, fingerboard or strings.
