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I placed remark about adsorbed natural gas in energy density table.But soon it have been deleted.Could I know what happened?There is lot of articles in Internet which prove that such technology really exist.It seems that ANG technology allows to store at least 2.5 times more gas than CNG under same pressure. [1]
— Preceding unsigned comment added by 70.73.149.123 ( talk) 16:44, 7 June 2009 (UTC)
Does anybody know what is maximal energy density of long-living soliton such as electric, magnetic etc.? Could it be mesured in kilojoules,megajoules? —Preceding unsigned comment added by 70.73.149.123 ( talk) 20:53, 21 January 2009 (UTC)
Would it be useful to split this large and wonderful table of energy densities into "destructive" and "non-destructive" energy stores? There is a large difference between burning your energy storage medium (or direct matter -> energy converstion!) and storing energy in a battery/turbine. 152.91.9.9 ( talk) 04:56, 7 May 2008 (UTC)
The ** thing a) looks stupid and b) is meaningless. There's no such thing as an "energy source". All of these are processes which can be used to store energy or as a source if you're supplied with the storage medium in its high energy state.
Distinctions which would be meaningful: Is it a reversible process (with how much loss)? Is the medium found in nature in its high energy state?
I think we should remove the ** and possibly add two new columns to indicate these boolean values.
Zkzkz ( talk) 20:00, 14 March 2008 (UTC)
the table lists "melting ice". should that be just "ICE"? MELTING ice absorbs energy. For that matter, should there just be a link to a table of phase-change energies of various materials? There's nothing THAT special about H2O in this respect. All phase changes can be viewed as energy storage. 216.107.193.67 ( talk) 10:58, 23 February 2008 (UTC)
I see that articles on various kinds of batteries claim they have a "high energy density". I want a single table that gives actual numbers. Is this the right place for such a table?
— Preceding unsigned comment added by 69.216.18.174 ( talk) 08:06, 19 February 2007 (UTC)
Thanks to all contributers for an EXCELLENT article!!! If anyone can obtain the information, I would LOVE to know the energy density of the following:
If adding too many materials makes the list too long, perhaps it can be broken into groups (e.g. explosives, nuclear physics, elastic, momentum etc). -- New Thought 12:02, 6 August 2006 (UTC)
Would like to see battery energy density covered here, with some common types listed, like lithium ion, alkaline, lead acid, NiCd, etc.
The flywheel entry should be removed. its not a constant -
66.92.33.119
20:00, 2 September 2006 (UTC)
Liquid hydrogen and compressed gaseous hydrogen at 700 bar should both have a higher energy per mass density than hydrogen at STP, because both do work as they expand. As an approximate calculation, 1 mole of ideal gas expanding isothermally from 700 bar to 1 bar at 300 K does 16340 J of work. Since hydrogren is 0.001 kg per mole, that gives an additional 16.3 MJ/kg for compressed hydrogren at 700 bar vs. hydrogren at STP. However, someone should find the exact numbers, because hydrogen isn't really an ideal gas, and the expansion isn't necessarily isothermal.
I would request the addition of molten salt energy storage (proposed for solar concentration techs). Also, is compressed air (300 bar) what is being proposed by companies such as General Compression for use with wind turbines? Overall, a great wiki article.
I say we merge. Thoughts? mastodon 22:22, 8 March 2006 (UTC)
This page should go into Hydrogen versus Batteries (electric) as the energy storage medium for transportation of the future.
zowie 23:55, 16 April 2006 (UTC)
It seems to me that for a given amount of, say, U235, there should be a given volume associated with that mass, and hence, an energy density by volume.
Are the entries just set to n/a because no one has done this calculation, or because such a calculation can't legitimately be done? And if they can't be done, could someone please add an explanation to the page explaining why they're marked n/a?
Otherwise, I'd guess one could take the average relative density of U235 and use the mass numbers to compute an average energy density by volume. It sounds like it would be very high: uranium is pretty dense, so 1KG of it would be pretty small.
Thoughts?
Maybe we should include the amount of mass converted into energy just for clarification. Intranetusa ( talk) 02:20, 25 January 2008 (UTC)
I don't know why, but it took me a minute or two to figure out why the numbers in the columns weren't monotonically increasing. I added the "by weight" and "by volume" sections so that no one else has to think too much about it. I couldn't figure out how to make the text normal (no bold, no italics). can any one else make it look better?
— Preceding unsigned comment added by 75.108.162.241 ( talk) 00:27, 27 September 2006 (UTC)
Btu/gal (both US and UK) are non-SI units, non metric system. It's time we got rid of such things, mostly because at the conversion of units page there are 8 different listings for the definition of Btu, and 4 different defintions for the gallon (UK and US). That's ridiculous. The metric system was designed a very long time ago to get rid such idiotic confusions, and make most conversions in metric as easy as moving the decimal point around, including converting between volume/mass using the aqueous sp.gr≈1 g/cc of water, then multiplying with actual sp.gr. In any case, for Btu/US gallon, using 1 Btu=0.0010550 MJ, and 1 gal=3.785412 L, I calculated 1MJ/L=3588.07 Btu/gal, while the factor used in the table seems to be around 4308 (Btu/gal) / (MJ/L). Can anyone highlight the source of such a large discrepancy? Sillybilly 18:46, 26 November 2006 (UTC)
I note that the data table here and the one in Fuel economy in automobiles contain some of the same information but with totally different values. I went through the table in that article and corrected the numbers that I was able to using the Bosch Automotive Handbook, which is a very authorative reference. The numbers in this table that should match are very different. This really does not reflect well on wikipedia in general.
I believe that we need to consider having this type of data contained in a separate article on properties of materials as it makes little sense to have separate tables in separate articles containing different values for the same physical properties. -- Athol Mullen 22:53, 26 November 2006 (UTC)
You are right. If you find better updated references, please fix the data. But I'd like to temper the attitude a bit, as far as expecting science to be super accurate. Yes, there are super accurate measurements for the speed of light, or for the unit electric charge, because they are so important, but a lot of the stuff just doesn't get enough lab measurement investment, and sometimes super accurate results are not of interest, but measurement cost and labtime cost is balanced with need. In particular I had to calculate a lot of the values by hand using http://webbook.nist.gov/chemistry/name-ser.html, and by no means am I as authoritative as a published source doing calculations, and I can make mistakes. Futher below there is an outline of what I did. Still small discrepancies in fuel values for crude oil and coal are acceptable, because, for instance, there is a discrepancy between what is meant by "gasoline" because gasoline is a blend of hydrocarbons, and varies from source to source, from oil well to oil well, and varies over time even from the same oil well. For instance aromatic hydrocarbons which have a higher octane values than alkanes, but lower MJ/kg fuel values because benzene's overall formula is C6H6, with a C:H ratio closer to 1:1, while alkanes are CnH2n+2 (n=7 for heptane, n=8 for octane), roughtly C:H closer to 1:2, more hydrogen than carbon meaning more MJ/kg. So small discrepancy between values might be understandable, perhaps a range should be given, instead of a value to 2 decimal places. When you buy gasoline, it is the octane value that's guaranteed, not the fuel value. On the other hand, the values for methanol and ethanol should be exact, because these are pure chemicals, and there is no excuse for the same 22.61 MJ/kg for both methanol and ethanol. So now I took the values from the fuel economy page and entered them here. Of course there is the water distillation azeotrope and 100% pure ethanol issue, which fuel is actually getting used, but the error in the value listed on this page was still huge, listing methanol and ethanol with the same value. It never occured to me to check values in that table that were already there when I came to this page. Note that discrepancy in reported values is not unusual, see [2] and [3] for values all over the place, though true, the error is less than what was originally on this page. I prefer going with the DOE reference on those pages. Still, here is a double check: At http://webbook.nist.gov/chemistry/name-ser.html we enter methanol, click search, click on condensed phase thermochemistry data, because we want to deal with the heat of formation of the liquid, not the gas, and find these values for ΔHf°, depending on reference:
ΔfH°liquid -238.4 kJ/mol Ccr Baroody and Carpenter, 1972 ALS
ΔfH°liquid -239.5 ± 0.2 kJ/mol Ccb Chao and Rossini, 1965 see Rossini, 1934; ALS
ΔfH°liquid -238.9 ± 3.6 kJ/mol Ccb Green, 1960 Reanalyzed by Cox and Pilcher, 1970, Original value = -238.5 ± 0.2 kJ/mol; ALS
ΔfH°liquid -250.6 kJ/mol Ccb Parks, 1925 ALS
I'm assuming these references are all actual lab measurements instead of citing yet another citation, because that's really the only way to tell. No matter how authoritative a published reference is, if you can't measure those values in a lab, then it's worthless. The ultimate authority is always with Nature and experimental measurement. The Ccr and Ccb above mean rotating and static bomb calorimetry methods. In view of using different experimental methods, the values are pretty close. Note the dates of measurements - more recent ones probably have better instrumentation. While the 239.5±0.2 Chao-Rossini value is from 1965, it says see Rossini 1934, it might actually be a 1965 published reference based on a 1934 measurement. Also, note how different the 1925 data is. So when picking a number to calculate with, we still have to pick whose labwork we want to rely on, and these numbers are actually wonderful, have a scientific feel to them, because too perfect data with too many decimal places is sometimes absurd. I don't like authoritative sources that are too accurate, I'd rather have a wild array of different sources with very little authority disregarding each other and each telling me a different number, and then I go an compare. This is real life. Your task is to pick a number out of thin air given these 5 values! You still have to do some picking, and it's better than the situation with an authoritative single answer. Also note that the 1960 Green value has a lot more error, ±3.6, but such numbers are still much preferable to dry numbers such as Baroody-Carpenter and Parks, without ± ranges given. I don't mind if the error is high, but still, give me the error. Technically all of our wikipedia energy density data should have a ± sign next to it, throughout the table, that would be true science. I highly dislike reading Premium Gasoline 32.84 MJ/L, 43.50 MJ/kg on the fuel economy page. 32.84, 4 signifcant digits? You're dreaming! Premium gasoline is not such a pure and uniquely identified material, moreover even the same exact sample will be measured different by different labs, or even the same lab. 32.8, or 33±2 is probably a normal answer. Anyway, back to cherry picking a ΔHf° for methanol, I like the value 238.9 kj/mol. How about you? So now we look at the combustion equation
CH3OH+1/2 O2-->CO2+2 H2O
ΔHf° for O2 is 0, by definition, but looking up the ΔHf° for CO2 and water both in the gas state at standard conditions - note your car doesn't exhaust gases at STP. In fact I don't even know off first hand what temperature is used for the NIST webbook data, some 3 minute of effort of mine went wasted trying to find out, I'm assuming all their ΔHf° values are given at the same reference temperature throughout, whether it's 20°C, 25°C or 0°C. So back to CO2 gas and H2O gas at reference condition, after doing some cherry picking (with much more accurate numbers), I come up with -393.5 and -241.83 kJ/mol.
So armed with these values, the ΔHf° for the overall reaction is 2*(-241.83)+(-393.5)-(-238.9)=638.26 kJ/mol liquid methanol combusted to water vapor and carbon dioxide cooled back to standard temperature. From the methanol page in wikipedia we find that the molar mass is 32.04 g methanol per mole. So that gives 638.26 kJ/32.04 g methanol, or 19.92 kJ/g, or 19.92 MJ/kg. Bingo, that number matches the fuel efficiency page and the DOE article, yay!, and not the 22.61 value that was on this page, so those two places seem to be more authoritative than the others, more trustworthy, because they match each other, plus they match the calculation I did based on a 3rd source. So now I'll take the values for ethanol found in both these authoritative places that match each other, the fuel efficiency wikipedia page and the DOE article, and hope they will be true. Note the real authoritative way is to redo the calculation for ethanol, and even then, the real authoritative way is going to the lab and doing the measurement yourself, because otherwise you have to trust someone else's labwork, something you read somewhere, and how do you know they didn't just pick it out of thin air? Multiple sources enhance trust, but you never get full certainty. Who's got all day and all life to keep doublechecking and calculating everything? Only paranoid people keep checking and checking things over and over because of mistrust. You mistrust everything by default, as a matter of fact, but you don't go around being obsessed with mistrust. When you come across an error you point it out and correct it, but sometimes false info gets quoted all over the world for a long time til it's realized it's wrong. Still, "given enough eyeballs, all bugs are shallow" is what wikipedia is about. Eventually all bugs should be hammered out, if it wasn't for all the pranksters and more subtle deliberate wikipedia derogators, wikipedia should gravitate to something better and better. By the way, to finish up the calculations, from the methanol wiki page we get the density as 0.7918 g/cm3, and doing a quick google on methanol msds specific gravity, we find 0.7910, 0.795 and 0.8, so the wikipedia number is "nice". Note that density to 4 significant digits probably requires temperature control to 3 significant digits or better. Ever try that, controlling temperature well within 0.1 °C? It's not easy. So, going with 0.7918 g/cm3, or .7918 kg/l, the 19.92 MJ/kg value translates to 19.92 MJ/kg * 0.7918 kg/L = 15.77 MJ/kg. Note 4 decimal place is absurd, because who will ever combust methanol and cool the exhaust vapors to standard conditions exactly? But anyway, you get the method, and you can calculate more such values for yourself, and double check values if you want. Sillybilly 08:54, 28 November 2006 (UTC)
See the heat of combustion and heating value pages for other set of values. Heat of combustion was understood here by me as the energy content, which represents the ΔH, enthalpy change, and then a second column with energy extraction efficiencies is added to deal with the subtle issues. All heat engines have low Carnot-cycle efficiencies, most cars being on the order of 25%, power plants on the order of 35% efficient. Technically, instead of enthalpy the ΔG, Gibbs free energy should be used, because that limits the availability of how much work can be extracted, or more exactly, gives you how much work can be extracted even from reactions without enthalpy change, but a significant ΔS entropy change (a large enough entropy change can drive a "negative heat of reaction" value, such as in ice packs [4], and can drive engines based on only entropy change). So, should we list the ΔG free energy values instead of the ΔH values as customary for fuel heating values? ΔG=ΔH - TΔS, T in Kelvins, (ex. 25°C=273.15K+25=298.15K, plug it in) you can do the above calculations again. But from the methanol combustion reaction 1.5 moles generating 3 moles, and gases at that from a liquid, the entropy change is very positive and a significant driver without even looking up the values, and gives "extra" energy values. The [5] page citing 22.034 MJ/kg for Methanol based on the ΔG Gibbs function instead of the 19.9 MJ/kg based on the ΔH heat of combustion bomb calorimeter value used by the DOE article citation. The difference is using two different meanings of stored energy - technically ΔG is what's correct, but ΔH is easier to measure. Technically there is some extra driving force present as entropy energy and that much more work(handed over as shaft power, battery electricity) could be extracted besides the heat energy driving force, because there is that extra nudge, extra form of thermodynamic energy present, in the form of entropy drive. But in view of the 30-50% efficiencies of even the best fuel cells, hairsplitting doesn't make sense, especially because the ΔG is very application dependent (i.e. is your upper Carnot cycle temperature in a natural gas combined cycle turbine 1200°C , or are you just dealing with just 150°C steam, the carnot efficiencies will vary tremendously, and but so will the ΔG values), so ΔG is very application dependent and highly sensitive to temperature, as noted in the equation ΔG=ΔH - TΔS, while ΔH is relatively constant for all temperatures, and therefore you can provide it as a single value with less confusion, even if it's technically not the "proper" energy storage value to cite. Still the ΔG° values should be the technically proper things to cite, because they represent the energy values that can be theoretically extracted from the system, whether it's more or less than the "heating value" ΔH part, based on how the entropy part happens to drive the system, whether it's positive and giving extra energy, or negative, consuming a large chunk of the heating value away, and in extreme cases, consuming it all. For instance, the reaction 2H2+O2--->2H2O has approx. the same ΔH value at any temperature, but an unfavorable negative entropy change, up to the point that at 2500°C the 3->2 molecule entropy reduction is so severe, that the reaction won't go forward at all, and no energy is extractable at all from hydrogen fuel, because ΔG is 0, or even negative, where water will thermolyse and self split up into H2 and O2 instead of H2 and O2 reacting together to give water. Thus hydrogen has a high heating value at any temperature, but less and less "free energy" extractable the higher the temperature. This fact is useful for high temperature electrolysis, but "unuseful" for high temperature fuel cells such as solid oxide fuel cells running at 1000°C, with low temperature Proton exchange membrane fuel cell running at 30°C giving better performance, at least as far as the ΔG part is concerned, or at least the "stored energy density" value is concerned. To reiterate again, the same hydrogen will look more energy rich, or have a higher energy density to a PEMFC than to an SOFC, simply because they operate at different temperatures, and if there were a fuel cell that ran at say 2499°C instead of 2500°C where it hits 0, the fuel value of hydrogen for it would be probaly less than 0.001 MJ/kg instead of the 120 listed in this table, calculable by ΔG. Above 2500°C the true fuel value, or ΔG would be 0. It's pointless to cite the standard free energy of formation at 25°C if your engine doesn't operate at 25°C. So that's another aspect of what "energy density" means at all. It's still important to have some kind of hierarchy and table listing these values, to get a good feel for things such as just how good a fuel gasoline is, how different batteries and liquid hydrogen are, and such things as fuel content of plastic, cow dung and household waste, even if the true fuel value, ΔG is such a vague concept without temperatures fixed to actual operating conditions. Sillybilly 09:24, 28 November 2006 (UTC)
mass-energy equivalence 89,876,000,000 MJ/kg protons in the Large Hadron Collider 6.7 ×10^14 MJ/kg
I know how the author thought this "protons in the Large Hadron Collider 6.7 ×10^14MJ/kg" but it's some missconception to say that energy of relativistic particle is the total relastivistic energy and the mass is only the rest mass (in stacionary state) so i thing there can't be written that energy densyty of something is grater than equal tu E=mc^2 eqantion, even hadron in hadron colider not, all energy has it's owen mass —The preceding unsigned comment was added by 147.32.122.137 ( talk) 00:49, 9 December 2006 (UTC).
Some years back I saw a theorem that related maximum achievable energy storage density to materials strength. (Not just restricted to mechanical-energy storage systems, as I recall.) Unfortunately I can't remember the details, and can't find the theorem now - any chance of somebody including this in the article? -- Calair 23:31, 13 December 2006 (UTC)
I think the compressed air at 200 bar value may be off. I do not see a source on the page, and when checking the NIST webbook for nitrogen (to get a good estimate) I see 0.171 MJ/kg which differs substantially ( http://webbook.nist.gov/cgi/fluid.cgi?Action=Load&ID=C7727379&Type=IsoTherm&PLow=200&PHigh=201&PInc=1&T=12&RefState=DEF&TUnit=C&PUnit=bar&DUnit=kg%2Fm3&HUnit=kJ%2Fkg&WUnit=m%2Fs&VisUnit=Pa*s&STUnit=N%2Fm). —Preceding unsigned comment added by Bavetta ( talk • contribs) 23:56, 13 August 2008 (UTC)
Yes, I think there is something wrong here with quoting numbers that can be :-
accurate figures for some chemicals,
good approximations for imprecise mixtures,
and wild guesses
The energy stored in a kilogram of gasoline/petrol is say 43 MJ/kg.
How much energy is stored in a stationary 1kg flywheel? And in one spinning at 10,000 RPM? And at 20,000 RPM. Maybe the article means the stored at the flywheels maximum RPM. Is it a large radius flywhel spinnin slowly, or a small radius flywheel spinning fast. Okay, the maximum energy stored might be independent of the flywheel size. Is it a hollow flywheel? What is it made from?
I believe the rotational speed of a flywheel is limited by the tensile strength of the material used and then the energy it will store is then further defined by the density of the material. I think either flywheel should be dropped from the list, or a very specific example should be quoted, eg solid carbon fibre disc of density 1750 kg/m3 and radius 10cm spinning at 50,000 RPM.
Other examples too like batteries will depend on how thick the container is and what it is made from, etc. If a reader is to have any confidence in the figures on Wikipedia, I think we need to separate usable scientific information eg chemical enthalpies, from rough guides that might indicate whether batteries of flywheels should be considered for a real world application, based on approximate values, or real values for very specific similar but different products.
If table entries can be coloured, I would favour a different colour scheme for measured scientific enthapies of combustion etc, eg ethanol, iso-octane, and finger in the air estimates, eg flywheel, battery.
Crysta1c1ear 17:55, 24 June 2007 (UTC)
Is a unit like BTU/scf also considered energy density? scf is not a unit of volume, but a unit of quantity. — Omegatron 03:32, 5 June 2007 (UTC)
NaBH4 <-> NaBO3 solution ... proposed by millenium for fuel cell chlorine to sodium chloride solution
can some knowledgeable soul run these?-- Oldboltonian 21:36, 6 June 2007 (UTC)
Liquid hydrogen and gaseous hydrogen do *not* have the same energy content -- gaseous hydrogen (room temp) has significantly more, by virtue of being warmer. The heat capacity of hydrogen is non-trivial. At atmospheric pressure, the difference is about 4MJ/kg. Reference: NIST thermophysical properties of fluid systems, [6].
—Preceding unsigned comment added by Evand ( talk • contribs) 03:15, 5 July 2007 (UTC)
hydrogen peroxide decomposition (as monopropellant) 0.33 MJ/kg ?? -It looks strange that energy density of this redox chemical reaction is as low energy density of melting ice. I made an approximative computation using AM1 semiempirical quantum mechanical method in Arguslab 4.0 and I got about 2.43 MJ/kg, the computation could be wrong of about 10% but not 10times. But I better discuse it before changing.
— Preceding unsigned comment added by 147.32.122.200 ( talk) 14:08, 12 July 2007 (UTC)
acording to http://www.du.edu/~jcalvert/phys/perox.htm the enthalpy of H2O2->H2O + O2 decomposition is 766cal/g*4.18~3.2MJ/Kg the value can also differ because of O2 expansion work and H2O heat of evaporization, but not much. So I changed this value.
also in main article about hydrogen peroxide http://en.wikipedia.org/wiki/Hydrogen_peroxide H of hydrogen peroxide is H=-98KJ/mol ~ 2.72MJ/Kg.
—Preceding unsigned comment added by ProkopHapala ( talk • contribs) 04:20, 16 July 2007 (UTC)
I was trying to track down a source for the energy content of 1kg of U-235. The only decent thing I could find was from the European Nuclear Society ( http://www.euronuclear.org/info/encyclopedia/coalequivalent.htm). They say "During the complete fission of 1 kg U-235, 19 billion kilocalories are released".
19 billion kcal = 7.9496 × (10^13) joules = 79.49 million MJ
I a little afraid of changing it though. If someone wanted to verify this and change the article I think it might be worth it. Thanks.
— Preceding unsigned comment added by 75.70.78.238 ( talk) 21:14, 24 July 2007 (UTC)
The figure in the table is 0.23 to 0.28 MJ/kg. However http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2763 is an example of a commercially available cell which is 0.72MJ/kg. The figures appear to be based on reference 2, which I'm rather surprised to find is only a few months old - meanwhile Dell for instance has been using laptop batteries with a better power density double what is quoted there for several years. I'd suggest that given it's totally inaccurate information, it is a very poor reference. I'll leave this in for discussion for a while, then if I remember dive in and modify the article (reluctant to do that straight away, as I don't have a good reference, just know that the one used at present is wrong). —Preceding unsigned comment added by 192.102.214.6 ( talk) 12:43, 3 March 2008 (UTC)
Surely there is no difference since energy can never be created, only transformed from one form to another (including mass).
161.51.43.37 ( talk) 03:08, 11 March 2008 (UTC) David McCarthy.
In requards th the comments at the top addressing the scientific relevance of this article, I have to point out that there are a lot of readers out there that are trying to get their heads around the energy problems of today, and as such this table really helps to give perspective to the many alternative energies being proposed. This may not be an important topic 50 years from now but for now we need it on wikipedia. However it might be appropriate to separate the table from the definition of Energy Density into its own article, perhaps labeled as Incomplete List of Energy Densities. On Hydrogen: If its being used to power a vehicle, its unlikely that the energy of its expansion will be captured so stop whining. I do agree that the table needs to be more specific. I came here to get an idea of how a car running on expanding liquid nitrogen compares with petrochemical engines, so for me the table needs to be clear that its talking about the "energy density of liquid hydrogen for combusting with oxygen", and for "liquid nitrogen to expand at STP" (if that is what the numbers actually represent). 76.212.147.34 ( talk) 11:09, 23 August 2008 (UTC) Sandy
this is indeed a brilliant article, but could I put in a plea for a subset to be viewable of all the stores and carriers likely to be of use in practical energy scenarios - power generation and storage and transport? All the other interesting ones like explosives and orbiters make it hard to compare the likely practical ones. Also there could usefully be a link to a purely electrical battery list. Engineman ( talk) 04:07, 5 September 2008 (UTC)
I tried to determine what was wrong with numeric-mode sorting in the table. There may be more than one cause (the table uses several obscure markups), but I believe I found at least one, and that is that wikipedia tables do not support formats like 4.32×104. Help:Sorting claims it does, but I suspect it is out of date, and so I made these two posts there. See Help talk:Sorting#Do not edit this copy? and Help talk:Sorting#Numeric sort test, and then meta:Help:Sorting. Note that it appears that smn support is also removed (I have no idea when it was ever working of course). - 84user ( talk) 04:04, 5 October 2008 (UTC)
The Energy Density of any substance used as Thermal Energy Storage is the sum of its latent and sensible energy densities over the temperature range used in the application. In that there are now real examples, and practical temperature ranges for those applications, It is important to compare the densities of Thermal energy Storage against batteries and other alternatives. I used 300 degrees C as a range, 300kj/kg for fusion, and 3kj/kg/c for sensible heat. These figures are in the rough range for a variety of PCMs used in High heat applications, although I could not find the particulars for Saltpeter as used in Barstow Solar II. The Energy Density is 1.2, but I rounded to ~1 because it is intended only to estimate the value for numerous possible examples in this space. Clarifications are encouraged. Best... Benjamin Gatti ( talk) 18:13, 2 November 2008 (UTC)
Could someone define where the MJ/L values for compressed air come from? Which volume do we take into account (decompressed at 0°C/24°C, compressed with/without bottle) and why does the bottle type matter? And even if the values are correct, they're certainly not that precise. Unless the article cites some sources, the values should be changed to one row like "compressed air at 300 bar with container - 0.05-0.50" Tokenzero ( talk) 12:44, 8 November 2008 (UTC)
A regenerative fuel cell is the only fuel cell that can be given a meaningful energy density. This is one that contains its own internal hydrogen store. Normal fuel cells are more like motors. Their energy density is meaningless as they burn fuel (usually Hydrogen but can be anything).
Mike Young ( talk) 22:51, 25 November 2008 (UTC)
Is the binding energy of Helium-4 nucleus correct (per litre)? How can it contain more energy than mass-energy equivalence? -- CharlesC ( talk) 11:00, 9 December 2008 (UTC)
I'm sure some have seen the recent granting of EEStor's patent. The patent papers claim 52 kWh from a "battery" (actually very accurate terminology in this case) massing 281 pounds. If I'm doing the conversions correctly that's 0.7 MJ/kg, a little bit lower than the number quoted here.
The weight is higher than I would have suspected at first guess, but it's about the same as a common 4-cylinder engine. Eliminating the transmission and fuel and replacing that with a motor might suggest overall curb weights will be slightly lower than ICE. Very interesting.
Maury Markowitz ( talk) 15:28, 22 December 2008 (UTC)
"Carbohydrates, fats, and proteins are the only sources of energy for an individual abstaining from alcohol, and they make up ninety percent of the dry weight of food."
I have a hard time making sense of this , vandalism ? aren't alcohol carbohydrates ? 69.172.116.133 ( talk) 19:34, 9 February 2010 (UTC)
I'm querying the data in the Energy Densities Table. Please review the data below for Natural Gas, with the examples of liquid Hydrogen, gaseous Hydrogen and Biodiesel added for contrast.
Storage Type | (MJ/kg) | (MJ/L) |
---|---|---|
Hydrogen, liquid (burned in air) | 143 | 10.1 |
Hydrogen, gas (burned in air) | 143 | 0.01079 |
Natural gas (burned in air) | 53.6 | 10 |
Biodiesel oil (vegetable oil) | 42.20 | 33 |
Are we saying that 1L of uncompressed Natural Gas has 10 MJ of energy, hence 1m^3 = 10,000MJ?
I refer to the following URL to support my query.
http://www.natural-gas.com.au/about/references.html
Fuel | MJ/m3 | MJ/kg |
---|---|---|
Natural Gas | 38.7 | 53.6 |
Therefore, I suppose the valve for Natural Gas should be 0.0387 MJ/L? —Preceding unsigned comment added by McGuinn ( talk • contribs) 22:28, 12 March 2009 (UTC)
I agree. Whoever entered 10 MJ/L for natural gas "burned in air" was clearly using the figure for compressed natural gas. I'll split this into two entries. -- Vaughan Pratt ( talk) 20:01, 5 June 2009 (UTC)
Please note that some of these values are the higher heating values. This is confusing as mostly the Lower Heating Value is used in industry!!!! There are interused in this table. For instance, for H2, the HHV is given, whereas for methanol, the LHV is given.
Didn't this table used to include a couple of entries for compressed air? I personally think that it was helpful to have them for relative comparison. —Preceding unsigned comment added by 98.175.228.222 ( talk) 22:43, 30 March 2009 (UTC)
Which chemical reaction has the highest energy per mass of the reactors? (just don't tell me the H2 and O2 is 143MJ/Kg, put the O2 in the calculation and it would be about 16MJ/Kg!) —Preceding unsigned comment added by 217.219.151.190 ( talk) 16:39, 9 August 2009 (UTC)
The cited 24 000 000 MJ/kg for natural uranium is the approximate value after conversion to electricity. The thermal energy density is 86 000 000 MJ/kg - mentioned in the Cohen paper. —Preceding unsigned comment added by Tweenk ( talk • contribs) 21:06, 13 December 2009 (UTC)
What would the energy density of fusion be if you added up all the fusions from hydrogen to iron? Eg how much energy would be release if you fused 1kg of hydrogen into bigger elements all the way to iron and how much of that kg would have been converted from mass into radiant energy? Would this be an approximation of the energy density of a large star formed from a hydrogen cloud? —Preceding unsigned comment added by 168.103.182.177 ( talk) 05:33, 15 January 2010 (UTC)
Is there some reason oxygen + hydrogen isn't on the list? According to the Rocket propellant page it is used in the Space Shuttle orbiter, the Centaur upper stage of the Atlas V, Saturn V upper stages, the newer Delta IV rocket, the H-IIA rocket, and most stages of the European Ariane rockets. 192.171.3.126 ( talk) 15:41, 1 June 2010 (UTC)
I am removing the practical recovery efficiency rating for the Natural Uranium in Fast Breeder Reactor, seeing how it only deals with thermal efficiency, not total power conversion efficiency. 173.66.0.205 ( talk) 06:56, 30 June 2010 (UTC)
Is it me or does this section appear to be unrelated to the rest of the article, and not really about anything? mavhc ( talk) 15:51, 8 November 2010 (UTC)
I assume that the SVG plot's data point for Natural Gas should be labled 'Methane 700bar' or similar? I believe the biggest component of natural gas is methane. Comments/corroboration welcome. Otherwise, excellent graphic. Tommyflockton ( talk) 11:19, 8 February 2011 (UTC)
Why is superheated water not on the list? — Preceding unsigned comment added by 60.228.216.171 ( talk) 16:34, 5 July 2011 (UTC)
I refer to this page frequently because it used to be a wonderful resource. However, now I see that most of the nuclear sources are gone except uranium. There is no mention of fusion in the table at all. The article reads "The highest density sources of energy outside of antimatter are fusion and fission." but doesn't give any numbers.
I don't want to just revert the table back to the way it was but the old version was much more useful. — Preceding unsigned comment added by 71.217.11.36 ( talk) 00:04, 17 July 2011 (UTC)
I didn't see a section here for this, so I'm making one.
Yes, by all means they should be merged. If anyone agrees/desires, I volunteer to do the work. beefman ( talk) 21:19, 16 January 2011 (UTC)
How come the lead acid car battery is different than the lead-acid battery in the table. These should be the same for the purposes of this article. 70.113.25.151 ( talk) 07:04, 29 July 2011 (UTC)
Folks, according to the EIA, ( [7] and [www.eia.gov/totalenergy/data/annual/pdf/sec8_3.pdf]), coal got converted to electricity at (19.19 quadrillion BTU) / (970 million short tons) = 23 megajoules / kilogram in 2012. If 24 MJ/kg is the maximum extractable energy density, we are operating our plants at 95% efficiency? I think not. Jcmcclurg ( talk) 22:01, 3 May 2012 (UTC)
The intro paragraph says that Hydrogen has a much lower energy density than gasoline, even in liquid form, but the tables list Hydrogen as having a much higher energy density in liquid form. Can someone reconcile these two contradictory statements? Tossrock ( talk) —Preceding undated comment added 02:46, 16 August 2011 (UTC).
Yes. The "energy densities" tables, in addition to energy density, *also* list specific energy.
According to the tables in this article, liquid hydrogen (10.1 MJ/L) has a much lower energy density than gasoline (34 MJ/L). In other words, a fuel tank with a volume of 1 liter can hold more energy if a person fills it with gasoline than if that person fills it with liquid hydrogen.
However, the tables also say liquid hydrogen (143 MJ/kg) has a much higher specific energy than gasoline (46.4 MJ/kg). In other words, when a hiker, airplane, elevator, rocket, etc. has only a limited amount of mass it can pick up, such a vehicle can can carry more energy if a person loads it with a kilogram of liquid hydrogen than if that person loads it with a kilogram of gasoline.
The intro paragraph currently says "hydrogen has a higher specific energy than gasoline does, but, even in liquid form, a much lower energy density.", which is entirely consistent with those tables.
Alas, it is very easy for a person to confuse "specific energy" with "energy density". How can we make this article less confusing? -- DavidCary ( talk) 18:24, 25 August 2011 (UTC)
Also add the energy density of nuclear fussion. — Preceding unsigned comment added by 70.176.87.72 ( talk) 01:04, 10 December 2011 (UTC)
http://www.niac.usra.edu/files/library/meetings/fellows/mar04/Edwards_Kenneth.pdf states "Specific Energy Antimatter = 180Mj / μg". While http://athena-positrons.web.cern.ch/ATHENA-positrons/wwwathena/FAQ.html states that "1 kg of antimatter with matter would generate an enormous amount of energy (9 · 10^16 J)"... that language may imply the energy is 90E15 "with" both the mass of matter and antimatter... I have been told by an astrophysicist "1 g of antimatter is about a gigawatt-day of energy". Someone please check my numbers... 1e9 J/s * 86400s = 86.4 Terajoules per gram (or approximately 90,000 Terajoules/kg).
I was thinking that it may not be a coincidence that the two values are a factor of 2 off, as the amount of mass required is exactly double if we include the required matter to accompany the antimatter for annihilation... but that would half the energy value not double it, so the 180*10^15 J/g seems like it may be the more real value. The matter-antimatter collider experiments probably produce very accurate numbers for this and I'm hoping to find a more accurate reference in one of the Fermilab Tevatron publications, but I'm not having much luck yet. I'm switching the page value back to 180000 TJ/kg until then. Luminaux ( talk) 05:25, 2 September 2011 (UTC)
This is a simple application of E=mc^2. If you want 500g of antimatter + 500g of matter (1kg total) then E=(1kg)(299 792 458m/s)^2=8.98755179e16 J (or J/kg). If you want a whole kg of antimatter (assuming the matter is provided by something else, much like oxygen begin supplied to a fire) then the answer is twice the previous calculation (1.797510358e^17 J/(kg of antimatter)) because you are annihilating two full kg of mass but only counting 1 of antimatter. I'm going to leave the 180 PJ/kg but change the page to be clear that this table is NOT including the mass of matter (I checked and the hydrogen doesn't include the oxygen as a quick test. It maybe good to double check that the others do not consider the mass of the other reactants) Hologram0110 ( talk) 17:16, 3 December 2011 (UTC)
Recently a reference to the Storm & Smith studies was injected into the discussion of uranium availability. These shoddy analyses amount to little more than hoaxes, since the stipulate that the Rössing uranium mine cannot exist, as it would consume more energy than is produced in the entire country of Namibia. More details here. -- Tweenk ( talk) 15:31, 11 February 2012 (UTC)
Why are the tables titled 'Energy densities ignoring external components' and 'Common energy densities' separate? I think they should be combined. They are listing the same information. I also don't like the efficiency information. Are you converting the potential energy into heat? into mechanical work? into electrical work? chemical work? It could be combined with the 'direct uses' column into a notes column. Hologram0110 ( talk) 17:28, 3 December 2011 (UTC)
The inclusion of the energy density of a 6-inch Subway Club Sandwich inspired me to some calculations which I present only for perspective and insight. I take no issue with the article by this post. The 1.3 MJ of energy listed for the sandwich is 1.3MJ x 277.8 watt-hours/MJ = 361 watt-hours. The lithium-ion (rechargeable) battery in my son's electric bicycle holds 36-volts x 10 ampere-hours = 360 watt-hours of energy. They are equal in energy content. Similarly, the 2,000 Calorie (food calories or kilo-calories) diet of a rather sedentary human provides 2,000 x 1.163 = 2,326 watt-hours of energy, equivalent to operating a 100-watt incandescent light bulb for 23.26 hours, or a 97-watt incandescent bulb 24 hours. Jkaness ( talk) 14:33, 12 October 2012 (UTC)
Question for the scientific community. The equation "1 Calorie = 1,000 calories" is true but confusing. Surely there is a deserving person for whom one of these "calorie" energy definitions could be re-named! Jkaness ( talk) 17:04, 12 October 2012 (UTC)
Hello, I think this table is was especially infromative to compare specific energy stored by different means, non only in fules, but also in any other means ( radioisotopes, capacitors, strings, explosives and many other ) I understant that for clarity and easiness for the reader, many things was removed from the main table. However, I don't think that it is good to trade information contend for clarity. I think it is possible also to provide extended version of this table with as many items as possible, just as a reference table. In order to keep this page clean and reasonably short, I recommand to make this as a sparate page.
This is why I started page Energy density Extended Reference Table — Preceding unsigned comment added by ProkopHapala ( talk • contribs) 09:50, 14 December 2012 (UTC)
The table gives a figure of 17 megajoules per kilogram, but most sources seem to agree that a kilogram of normal household sugar contains around 4000 calories, which would correspond to around 17 kilojoules, not 17 megajoules. Right?-- Distinguisher ( talk) 09:59, 18 January 2013 (UTC)
add energy density of anti-matter and energy density of Quantum vacuum — Preceding unsigned comment added by 108.49.217.56 ( talk) 01:02, 20 February 2013 (UTC)
Removed energy density of quantum vacuum, it's complete speculation and uncited. If you want to talk about this stuff, keep it to the page(s) that cover it; Energy Density is meant to be a reference page about current physics, not a discussion page about new physics.
TheNeutroniumAlchemist (
talk)
04:06, 25 February 2013 (UTC)
I get the gist of this sentence at the end of the intro:
"A pressure gradient has a potential to perform work on the surroundings by converting enthalpy until equilibrium is reached."
but I think the language is sloppy, since enthalpy doesn't change with the PV work described. It's the internal energy that's converted to work. I would change it only because differentiating enthalpy and energy is hard enough for new learners without compounding it with ambiguous statements.
173.25.54.191 ( talk) 02:31, 7 August 2013 (UTC)
It needs to be mentioned, if only in passing, that these figures are for COMBUSTION, in air (I assume) — Preceding unsigned comment added by 97.115.157.98 ( talk) 22:09, 20 August 2013 (UTC)
Right now the Energy densities of common energy storage materials table is unsourced, except for a circular reference to the Wikipedia page for Uranium-235.
This is quite unacceptable - we need a source for this data ASAP. What does everyone think about this document as the basis of the data used in the table on this page? The data table on page 2 is an aggregate of the studies quoted on pages 4-9 within that PDF.
Unless there is any dissent, I think this source should replace the current data. Stuart mcmillen ( talk) 10:51, 10 October 2013 (UTC)
Hi guys,
Various people have added some very interesting items to the table. I love the information, but I think certain items are not common enough to warrant inclusion in a table for laypeople. I've moved them here for future inclusion into an appropriate table:
Storage material | Energy type | MJ per kilogram | MJ per liter (litre) | Direct uses |
---|---|---|---|---|
Antimatter | Matter/antimatter | 180 000 000 000 [1] | 4.077e15 | Theoretical energy source |
Gas, hydrogen | Chemical | 142 | 0.01 - 8.5 | grid storage or conversion |
Jet fuel, Kerosene | Chemical | 43 | 33 | Jet engines |
Lithium air battery | Electrochemical | 9 | Portable electronic devices, electric vehicles | |
Carbon nanotube springs | Spring (device) | 7.2 [2] | Theoretical | |
Lithium-sulphur battery | Electrochemical | 1 | Electric vehicles | |
Supercapacitor (graphene/SWCNT electrode) [3] | Electrical | 0.56 | Electric vehicles, DC power smoothing | |
Sodium aqueous battery | Electrochemical | 0.367 | Load levelling, power smoothing, grid storage |
Hi, interesting thing: it's possible to keep greater energy density than matter-antimatter using just charges. A sphere made of only protons or electrons will contain an amount of potential energy that increases like it's charge squared, approximately, and will soon reach much greater energies than its mass converted to pure energy. It's very unstable I know, but antimatter too isn't something you can carry around that easily, besides you have to produce it just like this hypothetical object. Funny thing that what makes up everything around us (charged particles) is so dangerous in other forms. 2.230.238.141 ( talk) 22:46, 7 November 2013 (UTC)
Does anyone know what the energy density of Dimethyl ether is? Is it relevant on this chart? It is being proposed as more green diesel alternative. — Preceding unsigned comment added by MBizon ( talk • contribs) 09:08, 17 December 2013 (UTC)
Flywheel energy storage is quoted as having a specific energy of 0.36 - 0.5 MJ/kg. Although it is mechanical and can only store energy as rotation, I think it's relevant enough to be included in the table. -- 77.0.50.85 ( talk) 21:52, 4 March 2014 (UTC)
Comment is invited at Wikipedia_talk:Manual_of_Style/Dates_and_numbers#Proposal on the question of whether kWh (with no space and no dot) is an acceptable unit symbol for use in articles, as opposed to restricting the choices to kW·h or kW h (i.e. with either a space or a dot). EEng ( talk) 22:45, 30 July 2014 (UTC)
1. The "Planck density" entry was wrong so I removed it. 2. The "antimatter off by factor of 2" comment above is correct, except that the list is ambiguous about whether it counts just the mass of the fuel or fuel + reagent. 3. Where did we get the antimatter "MJ/L" line? Unlike the "MJ/kg" line, that should completely depend on what kind of antimatter you have and how densely you are storing it. Having a official "kg/L" for all antimatter is as nonsensical as having one for all matter. — Preceding unsigned comment added by RoadMap ( talk • contribs) 21:26, 8 October 2014 (UTC)
Right now there are many unsourced items in this table. This is quite unacceptable - we need a source for this data ASAP.
What does everyone think about this document as the basis of the fossil fuel data used in the table on this page? i.e. coal, oil, petrol, diesel, kerosene, hydrogen, etc.
The data table on page 2 is an aggregate of the studies quoted on pages 4-9 within that PDF. Unless there is any dissent, I think this source should replace the current data. Stuart mcmillen ( talk) 21:57, 25 November 2014 (UTC)
http://www.world-nuclear.org/info/Facts-and-Figures/Heat-values-of-various-fuels/ go for it. GangofOne ( talk) 06:03, 7 July 2015 (UTC)
The original author entered 10 to the 104th power, obviously wrong. I pointed this out with a comment in the page that was erased 5 minutes later. So I guessed it was a typo and the author meant to say 14th power so that is what I changed it to. But is it really 14th power??? I wanted someone to see my comment and think about it and put in the right number. Also not every reader is going to take the time like I did and edit the text. Some people might want to just put in a comment at the top of the edit screen that will hopefully be seen by a human maintainer and acted upon. — Preceding unsigned comment added by 172.8.156.52 ( talk) 20:38, 13 February 2015 (UTC)
I see no reliable source for the antimatter line in the table. Seems it could simply be removed until such time as someone locates a good source. N2e ( talk) 11:15, 6 July 2015 (UTC)
Liquid methane is becoming somewhat popular and common in new bipropellant liquid rocket engine development, with new engines being worked by the Russians, Chinese, and American (e.g., Project Morpheus) government space programs, as well as two large engines ( Raptor (rocket engine) and BE-4) being privately developed by two well-funded US private companies.
Therefore, it would be helpful to have some energy density numbers for "Methane, liquid" in the table in the article section Energy densities ignoring external components, where there is already "Hydrogen", "Hydrogen, liquid", and "Methane" (gaseous) entries in that table. Does anyone have a good source for these data? Cheers. N2e ( talk) 03:14, 11 January 2016 (UTC)
Hey, 1 kg of antimatter reacted with 1 kg of normal matter makes 180,000 TJ according to Einstein's famous equation. But doesn't that mean the energy density should be 180,000/2 = 90,000 TJ/kg?
Come to think of it, if we're using this paradigm, then all the fossil fuels (and hydrogen too) are wrong. We would need to factor in the mass of the O2 used in combustion, which would make all of values smaller. Since the article explicitly says it doesn't condsider things like oxidizers, maybe it is consistent after all? DrZygote214 ( talk) 05:10, 8 October 2014 (UTC)
A number of these numbers conflict with other parts of Wikipedia. For Instance Jet_fuel states 42MJ/KG vs the 46 here - AA 38.96.210.190 ( talk) 04:18, 22 August 2016 (UTC)
According to this paper: http://www.rsc.org/suppdata/ee/c0/c0ee00777c/c0ee00777c.pdf. C6/LiCoO2 (very popular battery) has an energy density of 1901 Wh/L which is 6.84 MJ/L, greater than that of compressed hydrogen. Both the table and figure list the upper limit at 2.63. Which might be more practical, but is FAR from the theoretical capabilities of these devices (gravimetric energy density should also be adjusted to 568 Wh/kg or 2.04 MJ/kg). — Preceding unsigned comment added by Viewsk8 ( talk • contribs) 19:06, 1 December 2016 (UTC)
While I realize the only nearest operational fusion reactor to date is 93 million miles away, it would still be nice to have an entry for it. How many joules are released by the fusion of a kg of H to form He in the Sun? (It's too hot to call it H2.) You'd think it would be stated clearly somewhere, but the
proton-proton chain reaction article is rather waffly and doesn't seem to offer a definitive answer I'm comfortable putting in the table.
Vaughan Pratt (
talk)
01:58, 6 January 2017 (UTC)
I created [Wh/L] column for better understanding instead of seeing density values in MJ/L, but if someone is familiar with the density of the materials, please include the [Wh/Kg] column too, which will be very practical and understandable and useful for everyone. Frozenprakash ( talk) 19:27, 3 January 2017 (UTC)
We do not use Joule in real life scenario, for detailed explanation, let me explain,
Different units of Energy,
Joule = Watt Second = 1 Watt consumed per second
Watt hour = 3600 Watt Second = 3600 Joule
KiloWatt hour = 1000 Wh = 3.6 Mega Joule
So, these above units are universally used while denoting energy storage, below are the examples,
Average battery storage capacity of different types [approximate values, for your understanding],
AAA [NiMH] = 1 Wh
AA [NiMH] = 2.5 Wh
AA [Li-ion] = 3 Wh
C [NiMH] = 5 Wh
D [NiMH] = 10 Wh
18650 [Li-ion] = 8 to 13 Wh
26650 [Li-ion] = 15 to 20 Wh
mAh and Ah are completely wrong units and marketing bluff, which doesn't give the energy capacity, as it's skips voltage,
so for same mAh or Ah, the energy [in Wh or kWh] is completely different with different voltages.
I hope now you know why we use kWh [Universal Electrical Unit] in home energy meter.
And Finally, Joule or Watt second [Ws], kilo Joule or kiloWatt Second [kWs] are used to rate the capacitor Energy,
For example, Maxwell 3.V Supercapacitor has around 3.85 Wh [13,860 Ws or 13.86 kWs],
but as the primary use of capacitor is to blast the power in couple of seconds or to charge in couple of seconds, thus Ws or kWs is commonly used to rate them [and humanely understandable too].
Even camera flashes were rated in Watt second per flash.
In general,
Power density are rated in [Watt / Kg] and
Energy density are rated in [Watt hour / Kg]
Now i hope you got bit of an understanding about the Watt and time used to define the energy !
Frozenprakash (
talk)
12:33, 10 January 2017 (UTC)
The figure of 80 million MJ/kg for nuclear fuel is a theoretical calculation based on fission rate. The actual energy obtained from a modern nuclear power plant is about 60GWday/tU (ton of uranium) or 5.2 million MJ/kg, only 1/16 of the number in the table, with the remaining 15/16 cooling its heels in the plant's spent fuel rod cooling pools and storage casks. What would be a reliable source for the 60GWday/tU figure? Would people accept http://www.plux.co.uk/energy-density-of-uranium/ as reliable? Vaughan Pratt ( talk) 18:54, 27 January 2017 (UTC)
In the table for different energy densities, diesel i listed as having 3.4 % higher energy/weight and 4.7 % higher energy/volume compared to gasoline. However on the wiki page for diesel " /info/en/?search=Diesel_fuel" diesel is said to have less energy/weight (only 0.2 % less) but significantly higher energy/volume (11 % higher) compared to gasoline.
Quote from diesel wiki-page:
I am not on expert on the differences between these fuels, but it is clear that there is a discrepancy between these two wiki pages (incorrect values?, different measurement techniques? or something else?) EV1TE ( talk) 15:08, 5 February 2017 (UTC)
What is the energy density of the red material used in a standard household wooden safety match? Or just the energy since I can easily weight a match head. Vaughan Pratt ( talk) 05:49, 17 March 2017 (UTC)
Is there any reason why inertial energy storage (fly wheels) is not included?-- Damorbel ( talk) 06:44, 24 July 2017 (UTC)
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