SCIENCE & TECHNOLOGY

Can Ethanol fuel an energy revolution?
By Radhakrishna Rao
F
OR long, South America’s resurgent economic power Brazil has been in the limelight for its runway success in using ethanol derived from sugarcane as an eco-friendly substitute for fossil fuel oil. However, the technology perfected by Brazil involves producing ethanol straight from sugarcane itself, instead of from sugar, through the route of alcohol.

Astronomers discover stars that could create a ‘super-sun’
By Simon Baker and  Martin Hickman
A
stronomers have pinpointed two massive stars orbiting close to each other in space that could merge to create a huge “super” sun, 100 times bigger than our own. The massive “binary” star system, located in a galaxy orbiting the Milky Way, has been captured by Nasa scientists using satellite and ground-based telescopes.

Prof Yash Pal

Prof Yash Pal

THIS UNIVERSE
PROF YASH PAL
A rainbow is formed because the water droplets in the atmosphere act as prisms. But then, why is only a single big rainbow formed?
This is a beautiful question. It raises the basic question: why do millions of tiny droplets hanging in the air after a rain collaborate to produce a beautiful arc of colour, even though we know that each of these drops is by itself capable of splitting the sunlight falling on it into colours?



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Can Ethanol fuel an energy revolution?
By Radhakrishna Rao

Tractors move sugar in a cargo terminal at Brazil’s Santos port. Brazil has been very successful in using ethanol, derived from sugarcane, as a fuel
Tractors move sugar in a cargo terminal at Brazil’s Santos port. Brazil has been very successful in using ethanol, derived from sugarcane, as a fuel. — Reuters photo

FOR long, South America’s resurgent economic power Brazil has been in the limelight for its runway success in using ethanol derived from sugarcane as an eco-friendly substitute for fossil fuel oil.

However, the technology perfected by Brazil involves producing ethanol straight from sugarcane itself, instead of from sugar, through the route of alcohol.

As energy experts and environmental researchers point out, as a feedstock for ethanol, cane, in terms of energy balance and conversion cost, is preferred to other food crops – especially maize, which is being used on a large enough scale to make bio-fuel.

Known as “Saudi Arabia of Ethanol”, Brazil produces about 200,000 barrels of bio-fuel in the form of ethanol every day. “Bio-fuels, especially ethanol, make for exciting investment opportunities. Given the right initiative, India can be the next Brazil”, says Vinod Khosla, a major member of the venture capital industry.

In the context of the progressively increasing sugarcane production in India, there is a growing demand for giving a boost to the ethanol production in the country. Right at the moment, India grows sugarcane on around 4.5-million hectares.

Indian sugar mills produce about 733-million litres of ethanol per year. The Government of India, on its part, is keen that the percentage of ethanol doping of fuel oil be doubled to 10 per cent by mid-2007. As pointed out by Jai Uppal, an expert on bio-fuels, “Today ethanol can match the price of petrol in Brazil even if the price of crude oil drops to $26 without any subsidy”.

Across the world, vigorous and sustained efforts are on to improve the quality and efficiency of ethanol and turn it into a cleaner and economically viable alternative to gasoline used in piston engines.

However, researchers specialising in aviation energy sources point out that there are still many hurdles that need to be crossed before ethanol graduates into a widely accepted alternative to aviation gasoline .” While ethanol is a very good fuel for piston engines, it is not suitable for jet engines” says Dr .Max Shauck, a pioneer for ethanol in aviation.

As energy experts point out, ethanol, because of its low specific energy, is not quite suitable for use as fuel in gas turbines. Decreased engine power is a nagging issue associated with the use of ethanol as an aviation fuel. “It takes a lot more fuel to produce the same power,” says Skip Byrnes, an aviation energy expert.

Yet another concern that is commonly associated with the use of ethanol as an energy alternative is its uncertain effect on the engines. There are worries over the possibility of corrosion affecting the system.

Another handicap, says John Heimlich, Chief Economist of the air transport association, the trade body of the US airlines, “It freezes in pipelines. It is one thing to have fuel; it is another to get it into the aircraft.”

And as things stand now, a lot more trials and technological up-gradations need to be carried out to make ethanol a widely accepted fuel for use in mass transportation including air transportation.

Across the world, efforts are on to improve the quality and efficiency of ethanol and turn it into a cleaner and economically viable alternative to gasoline used in piston engines.
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Astronomers discover stars that could create a ‘super-sun’
By Simon Baker and Martin Hickman

Astronomers have pinpointed two massive stars orbiting close to each other in space that could merge to create a huge “super” sun, 100 times bigger than our own.

The massive “binary” star system, located in a galaxy orbiting the Milky Way, has been captured by Nasa scientists using satellite and ground-based telescopes.

It is one of the most “extreme” systems of its type known to astronomers and, at less than 3 million years old, is also relatively young, The stars, around 165,000 light years from Earth and labeled LH54-425 by astronomers, each contain about 62 and 37 times the mass of our Sun.

As they age and swell in size, scientists believe they will begin to transfer massive amounts of mass to each other.

Eventually they are likely to merge, producing a single huge star to rival one of the largest found in the Milky Way: the Eta Carinae binary system.

“The merger of two massive stars to make a single super star of over 80 suns could lead to an object like Eta Carinae, which might have looked like LH54-425 one million years ago,” said George Sonneborn, of Nasa.

“Finding stars this massive so early in their life is very rare. These results expand our understanding of the nature of very massive binaries, which was not well understood.

“The system will eventually produce a very energetic supernova.” Rosina Iping, of the Catholic University, Washington, remarked: “These stars are evolving in the blink of an eye compared to the sun, which has looked pretty much the same for over 4 billion years.

“But this binary looks totally different from Eta Carinae even though there is maybe only one million years difference in age. Will it produce something like Eta Carinae? We don’t know.” Nasa speculated earlier this month that Eta Carinae may be about to explode. It devised the theory after deciding that the brightest stellar explosion ever recorded could be a new type of supernova.

Violent explosions of extremely massive stars now seem to have been relatively common in the early universe and a similar explosion might be ready to go off in the Milky Way, astronomers said.

“This was a truly monstrous explosion, a hundred times more energetic than a typical supernova,” said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas in Austin.

“That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We’ve never seen that before.” The discovery of the supernova, SN 2006gy, provided evidence that the death of such massive stars was “fundamentally different” from theoretical predictions. The star that produced SN 2006gy apparently expelled a large amount of mass prior to exploding. Eta Carinae too has been losing mass.

“We don’t know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case,” said Mario Livio of the Space Telescope Science Institute in Baltimore.

“Eta Carinae’s explosion could be the best star-show in the history of modern civilization.”

By arrangement with The Independent
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THIS UNIVERSE
PROF YASH PAL

A rainbow is formed because the water droplets in the atmosphere act as prisms. But then, why is only a single big rainbow formed?

This is a beautiful question. It raises the basic question: why do millions of tiny droplets hanging in the air after a rain collaborate to produce a beautiful arc of colour, even though we know that each of these drops is by itself capable of splitting the sunlight falling on it into colours?

In a sentiment once expressed by Rabindranath Tagore there seems to be a conspiracy in nature to give us delight! The physics behind this conspiracy is the following:

The sunlight falling on a droplet suffers refraction and dispersion. This refracted light goes through a total internal reflection at the back surface of the drop and is subjected to another refraction and dispersion before emerging from the drop. The direction in which the emerging light will go will depend on the angle of incidence on the surface of the drop. It turns out, as in the case of prisms, that most of the rays emerge close to an angle where the deviation with respect to the incident ray is minimum. For water, this angle of minimum deviation turns out to be 42 degrees.

This means that an observer will preferably see those of the rays that have suffered the refraction, dispersion and total internal reflection in raindrops in a cone of 42-degree angle. That is the rainbow we see. The drops that are working for that observer lie in that narrow cone, all through the atmosphere. For observers standing some distance apart these drops will lie in their private but indistinguishable cones. It is wonderful to realize that all of us can claim an ownership of our rainbow, even though it is exactly similar to any other.
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