The idea that energy can be converted (not created) from one form into another fits in our intuition. We are willing to accept that we can not get more energy than the energy contained in the source. We also know that during conversion some energy is lost to heat or friction (in case of moving systems). We aren’t however clear about the the logical conclusion of these two statements.
Energy is convertible (e.g. coal to heat, water dam to turbine’s spinning etc.) but it isn’t freely convertible. The process of energy conversion is governed by the second law of thermodynamics which states the entropy (a measure of ‘disorder’) of a closed system always increases during the conversion. Water that is neatly ‘arranged’ in a dam is flowing in a stream (less arranged, more disorderly than still water). We can not put it back in ‘arranged’ form in its original place without pumping it back or without putting more energy into it than what we got out of its running down. We can’t use the heat we obtained by burning coal to put it (the ash) back into the form of coal. The energy lost in the form of heat or friction corresponds to increase in disorderliness.
If we apply the above principles we can understand that energy of one kind cannot be regarded as equivalent to energy of another kind. For example, one joule of solar energy has a smaller ability to do work then one joule of energy contained in coal, since the coal energy is more concentrated than the solar energy. Whenever we try to extract energy from sun rays some energy gets lost as heat. Bigger solar panels catching more sun rays will generate more heat. There are thermodynamic and quantum limits to efficiency of solar panels.
‘Better’ solar cells too involve manufacturing that is dependent on and presupposes the existence of a complex global industrial manufacturing system. This comprises not only the fabrication systems typically accounted for in estimates of manufacturing energy, but the contingent mining, refining and global transportation systems, as well as other energy intensive critical support systems including finance, information, and security systems. The uncertainty of that energy component confers uncertainty on any estimate of payback times derived from that estimate, considered by some to be significant.
We will substitute one form of mining by another, we will re-distribute heat loss between point of manufacture and consumption if we substitute coal energy by solar energy.
Solar energy may seem to be clean (and even free) if we don’t take into account energy used in manufacture, transportation, installation, and regular cleaning of panels. But it isn’t. It also generates heat.
According to The second law of thermodynamics coal as an energy source is more efficient therefore more ‘green’ than the solar energy. Geological forces acting over forests buried in earthquakes tens of thousand of years have concentrated energy in coal in compact (lower entropy) form than the sun rays.
I will try to cover other issues (not directly related to Physics) related to use of coal or fossil fuels (or even solar panels) at some other time.
I know there will be protests by the greens over this. But I would welcome discussion based of physics. That will be enlightening.
and The New Wall Hanging..
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A water lens
When I saw this glass of water I remembered a physics lesson that a curved body of water can act as a lens due to its light bending ways.
As usual my Moto G came handy.The image needed some processing.
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Clearly an industry lobby is at work here. It beats me, how electric vehicles can be qualified as green.
image source wikipedia
To be called ‘green’ any gadget or technology should be clearly more energy efficient and less polluting than more established alternatives. Electric vehicles don’t pollute the air on the roads. But from where the energy for charging batteries comes from? If you consider all the conversion and transmission losses from the generating station thousands of miles away to the battery charging station in a city much more additional electrical energy needs to be generated. So you just shift pollution from roads to a power stations usually running on coal. Costs and pollution hazards due to chemicals used in batteries is another factor. Moreover, traditional petrol and diesel vehicles are becoming less and less polluting as laws are being tightened.
GM and Mahindra of the auto world would be happy get tax breaks on these vehicles for their Volt and Reva. but I don’t see any logic. I have no problem with electric vehicles being around as an option to traditional vehicles.
Tax dollars or Rupees are better spent on public transport support because it much more energy efficient, it reduces road congestion, lowers pollution per capita and therefore it must have preemptive right over tax concessions.
Ever since I started running about four years back, running has brought me many gifts -confidence, patience, focus, and wonderful new friends.
Today it brought me something tangible!
I run with a friend. His brother-in-law got both of us a cap with LED lamps! Perfect for starting our ling runs in pre-dawn darkness. This will help avoid stumbling on broken tiles, stones or some other obstacles. The cap will keep us visible to others too.
So thoughtful of him. isn’t it?
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My friend sent me a very insightful article a few days back. The writer had nicely captured the essence of difference between routine and ritual. When we were chatting about it, my friend remarked, “I wish I could write like that. I can’t write because I can’t think so well’. She is an extremely talented person. She paints, she creates beautiful artifacts, and she does visual design as her profession. I would happily trade my meager writing skills for her kind of skills. I tried telling her that she thinks through her paintings and her creations. But she wasn’t convinced.
So I thought, why does she say that?
A scene unfolded in front me. Pandit Kumar Gandharva was singing. He wasn’t singing, the gods were singing through him. The audience was in raptures. It was many many years back, but I still recall what happened to me vividly. A feeling of complete abandon came over me. It was as if I was there and i wasn’t there. Nothing mattered. I felt so small that I existed only to feel it,
When read Henry Miller’s Rosy Crucifixion, and his Tropic of Cancer I felt the same way.
When you watch a sublime straight drive by Sachin, with seemingly no effort, you feel the same.
I had a thought. What you experience when you read a well written passage, listen a beautiful melody, or see a nice painting you experiences years of hard work, practice struggle, efforts to overcome setbacks in one final grand culmination. Everything has come together. Everything is perfect. It is God like. Mo matter who we are, we as individuals are frail and imperfect. Therefore we feel small. We feel humbled.
It is an exquisite feeling.