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 Subject: Percent efficiency in transforming energy Category: Science > Technology Asked by: gmm765-ga List Price: \$10.00 Posted: 20 Nov 2006 19:11 PST Expires: 20 Dec 2006 19:11 PST Question ID: 784410
 ```I am looking for a table or list which has the percentage of efficiency when you transform energy from one from to another. I'd like to find a comprehensive list. Please start by listing the major forms of energy--electrical, light, chemical etc, etc ( i don't know them all), then all the ways they can be transformed and the percentage efficiency. It would seem to me that this would be essential foundation knowledge for all engineers, but I haven't been able to find it on the web. I'd am willing to go upward in price to get this, so let me know how long you think it will take, where you will search, and how much you want.``` Clarification of Question by gmm765-ga on 20 Nov 2006 19:23 PST ```Oh about the e=mc squared stuff. This isn't something I am particularly concerned with, but it would be nice to see some thoughts on the efficiency of transforming matter into energy.```
 ```gmm 1) Limit on efficiency of conversion, based on energy type is given by Carnot's formula. Sadi Carnot was an engineer who wondered what is a limit on efficiency of steam engines. http://en.wikipedia.org/wiki/Nicolas_Léonard_Sadi_Carnot The formula (better then list, certainly) may be complex, and the concept is very complex and often misinterpreted in popular presentations http://en.wikipedia.org/wiki/Entropy but your statement " It would seem to me that this would be essential foundation knowledge " and your intuition are correct. Carnot's answer became foundation of thermodynamics, which today applies to all conversion precesses, not just to heat engines. 2) E=m *c^2 , contrary to popular opinion, does not refer to conversion of one from of energy into another, nor conversion of matter into energy. This is best seen when we use 'planck units' in which c=1 http://en.wikipedia.org/wiki/Planck_units the formula is then E=m and means that two physical quantities of Newtonian physics, E and m are replaced by one quantity in the relativistic physics. This quantity (a forth component of four-vector for linear momentum) can be interpreted as sum of mass and all energies in the classical (Newtonian) limit. This formula: http://upload.wikimedia.org/math/4/5/a/45a51c034dd2c497ebabe4229a189e0e.png from this article http://en.wikipedia.org/wiki/Relativistic_mass under 'Kinetic energy' heading ilustrates this: when v/c tends to zero, the higher order terms tend to zero and we are left with E as sum of mass and kinetic energy. The formula (eq 9) is derived here http://www.marco-learningsystems.com/pages/sawyer/thermo.htm SEARCH TERMS; entropy, 2nd law of thermodynamics theory http://mooni.fccj.org/~ethall/thermo/thermo.htm example of application http://www.leuveninc.com/pooled/articles/BF_EVENTART/view.asp?Q=BF_EVENTART_62050 SEARCH TERMS; STR, special theory of relativity In both case, it is advisable to be critical. There is a lot of 'entropy' on the web, on both topics. You are invitied to ask for clarification before you rate the answer, but not to argue with the current mainstream theories of physics.``` Request for Answer Clarification by gmm765-ga on 25 Nov 2006 17:27 PST ```I thought that carnot's efficiency theorum (1- Temp-cold/temp-hot)only applied to heat engines? I do understand how this applies to internal combustion engines, but electrical energy into heat? Or the other forms? Let's start with the types of energy: Mechanical, electrical, heat, gravitational, magnetic, chemical .Are you saying that carnot theorum applies in all these cases? How? Please list other types of energy besides the ones I've listed.I am not familiar with how energy is conceptually broken down, and maybe you could clarify that for me. More. The carnot efficiency is an idealized and theoretical approach. I am more interested in a practical , empirical look at the best energy transfers percentage that we know of. Is there someplace that knowledge has been collected? I would think that such a collection of knowledge would be a godsend to engineers that design things for the real world, but I have not been able to find it. Oh and I am only interested in learning about what IS accepted by physicists. That is, I am not one of those perpetual motion guys, or one of those people who is challenging the accepted laws of physics. Also,sticking with Newtonian physics is fine! Thanks Hope to hear from you Geoff``` Clarification of Answer by hedgie-ga on 25 Nov 2006 18:56 PST ```Hi Geoff, nice hearing from you Let me finish the section 2) first, then we will stick with non-relativistic mechanics, with thermodynamics really. re 2) mc^c PBS has a nice presentation on the famous eq. (search term) mc2 How do physicists explain Einstein's equation to curious non-physicists? Listen online by selecting Play All or choose individual clips below. Listen offline by downloading clips, http://www.pbs.org/wgbh/nova/Einstein/experts.html they asked 10 physicists to explain - and explanations differ not because it is an open question, but because in 3 minutes it is not possible to explain What is energy? what is matter? we talk about that a bit in: Pure Energy...Yes or No? http://answers.google.com/answers/threadview?id=483779 http://answers.google.com/answers/threadview?id=475235 Part of the differences is in treating expression 'nuclear energy' differently. Formula E=Mc^2 covers all processes, all energy conversions, chemical, nuclear, etc. But it more useful in nuclear and elementary particles (annihilation of positron and electron) then in case of chemical reaction. That's why people, even physicist, quote in the nuclear and particle physics is if it would be specific to those processes. re 1) Carnot's formula applies to the heat engines. It is very practical (Carnot was an engineer) and is clever since it pioneered the use of Carnot cycle. There are many different substances, steam-water, freon, etc which can be used to build a heat engine. One can go and try different substances, hoping to Find most 'efficient one' . Carnot reasoning did show that WITH ANY substance, efficiency is limited by his formula. That was the beginning of Thermodynamics. Today it applies to all energy conversions, from heat to nuclear. Today's answer to your question is the 2nd law: Best conversion process you can invent, is the one in which entropy does not change ( an isentropic or quasi-stationer process). All other processes have entropy going up, more or less, and so are 'less efficient' The formulas for entropy may be complex. Carnot's is a simple formula which applies to heat engines. Second law applies to all processes, all conversions. http://en.wikipedia.org/wiki/Second_law_of_thermodynamics http://www.shakespeare2ndlaw.com/ http://www.2ndlaw.com/entropy.html Expression 'forms of energy' is not exactly defined. 'Wind energy' can be a category in itself, or it can be kinetic and internal energy of atmosphere gases. Here are few 'official' lists: http://www.eia.doe.gov/kids/energyfacts/science/formsofenergy.html http://www.need.org/needpdf/FormsofEnergy.pdf http://en.wikipedia.org/wiki/Energy Example: When you have a rock on a high platform , at height h, in gravity field g .. it has potential energy m*g*h right? You kick it down, before it hits, it has kinetic energy corresponding to m*g*h .. nothing is lost, because entropy did not change. After it hits, most energy is dissipated (not LOST!!) and entropy increased. That increase depends on the properties of the rock and floor, and can be calculated. That's how it is. ok? Hedgie```
 ```Generally, the percentage efficiency depends on the characteristics of the process you use. There is a wide range of efficiencies. Think of automobile engines. Some are fairly efficient and some aren't. You can change the efficiency by changing the operating temperature, fuel, carburetion, combustion chambers, valves, timing, exhaust system, etc.```
 ```Well, I am aware that the characteristics of the process can effect the efficiency. Maybe I didn't make this clear, but the whole point of answering this question is to get a fix on what is most efficient in transforming energy from one type to another. In the case of the internal combustion engines, I think it's generally agreed that gasoline engines are able to get around 18% efficiency in turning the energy in the liquid into motion, Diesel is about 38% and the stirling is 50% plus. I don't need a detailed explanation of the history of carburetion, or the development of computer controlled combustion, but if the hemi engine ( a cylindrical top to the combustion chamber which prevents btu's from escaping the cylcinders) represents the most efficient internal combustion engine, then engineers should know this, and I'd like to see that in the chart. Does the hemi diesel give us the the best efficiency for internal combustion ---that we know of? That is the sort of thing I'd like to know. And the percentage efficiency would go into the row( in our effieciency chart) entitled "chemical energy to physical motion." Hope that clarifies.```