The following information may have errors; It is not permissible to be read by anyone who has ever met a lawyer. Use should also be confined to Engineers with more than 370 course hours of electronic engineering and should only be used for theoretical studies. All content entered becomes and is (C)2007 Transtronics, Inc. the property of Transtronics, Inc. Rest assured that your contributions won't be sold and will be publicly available.
Energy density
From Transwiki
Contents |
[edit] Energy Density
[edit] Fuel Volumetric and Gravimetric Energy Density compared
[edit] Or neglected Real-world physics
Please post or send in (to inform@xtronics.com ) any other densities you are familiar with to add to this page.
| Energy Density sorted by Wh/l | |||||
|---|---|---|---|---|---|
| Material | Volumetric | Gravimetric | Deep cycle life Number of cycles | 80% Cycle life Number of 80% cycles | Approx cost Per total kWh delivered |
| Fission of U-235 | 4.7 x 1012 Wh/l | 2.5 x1010 Wh/kg | |||
| Boron | 38,278 Wh/l | 16361 Wh/kg | |||
| JP10 (dicyclopentadiene) | 10,975 Wh/l | 11,694 | |||
| Diesel | 10,942Wh/l | 13,762 Wh/kg | |||
| Gasoline | 9,700 Wh/l | 12,200 Wh/kg | $0.0814/kwh 11-2007 | ||
| Black Coal solid =>CO2 | 9444 Wh/l | 6667Wh/kg | |||
| LNG | 7,216 Wh/l | 12,100 Wh/kg | |||
| Propane (liquid) | 7,500 - 6,600 Wh/l | 13,900 Wh/kg | |||
| Black Coal Bulk =>CO2 | 6278 Wh/l | 6667Wh/kg | |||
| Ethanol | 6,100 Wh/l | 7,850 Wh/kg | |||
| hydrazine (Mono-propellant) | 5,426 Wh/l | 5,373 Wh/kg | |||
| Thermite Fe2O3(s) + 2Al(s) -> Al2O3(s) + 2Fe(s) (mono fuel) | 5,114 Wh/l | 1,111 Wh/kg | |||
| Methanol | 4,600 Wh/l | 6,400 Wh/kg | |||
| Sodium Borohydride Theoretical Hydrogen battery | 7,314 Wh/l theoretical 2,925Wh/l real | 7,100 Wh/kg theoretical 2,840 Wh/kg real | |||
| Liquid H2 | 2,600 Wh/l | 39,000† Wh/kg | |||
| Hydrogen Peroxide 100% (mono-propellant rocket fuel) | 1,187 Wh/l | 813 Wh/kg | |||
| LiFePO4 | 970Wh/l | 439Wh/kg | 1000? method not specified.. | ||
| Wood Varies with | 500 -900Wh/l | 1,600 - 4,709 Wh/kg | |||
| 150 Bar H2 | 405 Wh/l | 39,000† Wh/kg | |||
| Secondary Lithium - ion Polymer | 300 Wh/l ?? | 130 - 1200 Wh/kg | |||
| Secondary Lithium-Ion | 300 Wh/l | 110 Wh/kg | |||
| Primary Zinc-Air | 240 Wh/l 1000Wh/l ??Best? | 300 Wh/kg 440Wh/kg> | |||
| Dry ice sublimation | 248 Wh/l | 159 Wh/kg | |||
| Primary Lithium Sulfur Dioxide | 190 Wh/l | 170 Wh/kg | |||
| Nickel Metal Hydride (not discounted for | 100 Wh/l | 60Wh/kg | |||
| Wood pellets (pelletizing energy subtracted?) | 100†† Wh/l | 4,700 Wh/kg | |||
| Flywheel | 210 Wh/l | 120 Wh/kg | |||
| Liquid N2 | 65 Wh/l | 55 Wh/kg | |||
| Lead Acid Battery | 40 Wh/l | 25 Wh/kg | 300 | $1.58/kWh | |
| Propane (Gas - 1 bar) | 28.1 Wh/l | 13,900 Wh/kg | |||
| Compressed Air | 17 Wh/l | 34 Wh/kg | |||
| Ice to water | 9.3 Wh/l | 9.3 Wh/kg | |||
| STP H2 | 2.7 Wh/l | 39,000† Wh/kg | |||
| Boost cap | 1.72Wh/l | 2.98 Wh/kg | |||
|
† = without container Some numbers from Don Lancaster †† - seems low? ††† Types of coal vary widely - coal => CO2 4816 - 8722 Wh/kg | |||||
Let's see.. Maybe gasoline is the fuel of choice ... because of it's volumetric energy density? And liquid hydrogen makes good rocket fuel because of its gravimetric energy density?
Reality: a gallon of Gasoline has more hydrogen than a gallon of liquid hydrogen - in other words gasoline is a great way to store hydrogen fuel. The only economic source of hydrogen at this time is oil anyway. You could write your congressman to change the laws of physics. Often, reality doesn't fit our emotional wants and desires, but reality can be a stubborn thing to deal with - it doesn't go away when you quit believing in it.
The numbers compiled here varied a bit - the definitions of gasoline and diesel are not precise; Gasoline and diesel fuel are a mixture of about 100 different molecules who's ratios vary from batch to batch. Diesel fuel should be very similar to gasoline. Diesel is preferred for trucks due to torque/rpm curves. A turbine should have about the best hydrocarbon economy - BUT it must be run in a very narrow range to archive that and has a very slow ramp up making it uneconomical for cars and trucks.
[edit] Battery calculation that gets ignored
(We call this arm waving of 'venture vultures'1 -- note that venture vultures can't really fly no mater how hard they flap their arms)
On rechargeable batteries there is a cycle life time - often 100 - 400 (some claims of 1000 - but with hugely derated use). If you take the capacity of the battery times the number of cycles you get a total energy out over the life time of the battery. This then can be used to calculate a Wh/cost so it can be compared to primary fuels - such as gasoline. Even ignoring the cost of the energy required to recharge these batteries, the costs are not in the ball park for vehicular use.
[edit] Some Fuels that won't work
[edit] Bio Fuel
Very limited supply of used cooking oil - Moving from food crops to fuel will cause starvation and produce a lot of pollution. Recently(2007), the University of Wisconsin in Madison has come up with a way to convert sugar to a fuel (2,5-dimethylfuran (DMF)) with 40% more energy density than ethanol which would put it on par with gasoline. [1].
[edit] Solar Cells
As of today (2007), it takes about 20 years of constant use to get the energy used in manufacturer back out [2] - if the life span of solar cells last that long. Perhaps lower energy manufacturing methods will one day be figured out - they would have to be a magnitude or two improved to make these practical.
See discussion on talk page
[edit] Hydrogen
Embrittles its container (explodes pores in metals - forms brittle hydrates) is one of the most dangerous gases to handle - explosive from 4 - 96% concentration. You would have to store vehicles outside - no tunnel use etc. Besides the most economical way to produce hydrogen is from oil - Best way to store hydrogen is as gasoline - as there is more hydrogen in a gallon of Gasoline than in a gallon of liquid hydrogen. In any article you read about hydrogen, it is a good idea to replace the words"hydrogen economy" with "boondoggle" to get a clearer meaning. We have moved some comments to the discussion area.
[edit] Batteries
No one talks about battery wear out - energy density goes down as the batteries wear out. Manufacturing exotic batteries causes more pollution than they could possibly prevent. Energy density is still 2 magnitudes from practical compared to Gasoline and ICE.
There is also the issue of battery efficiency. Energy efficiency is calculated on the amount of power used from the battery while discharging divided by the amount of power delivered to the batter while charging, multiplied by 100 to yield percent. Pout x 100 /Pin . A lead-acid battery has an efficiency of only 75-85%. The energy lost appears as heat and warms the battery. Keeping the charge and discharge rate of a battery low, helps keep a battery cool and improves the battery life.
The above losses don't include losses in the charging circuit which may have an efficiency of anywhere from 60% to 80% - thus the overall- total efficiency is the product of these efficiencies and ends up being 45 to 68%. (To further this example and to show why physics and not some corporate conspiracy is the reason we don't have electric cars - suppose the controls and motors on a car were 85% - the over all efficiency is now only 38 - 58%. You can see that an electric car would use about twice the energy than a conventional car - not to mention the great cost of the regular replacement of batteries. This is why batteries are best used where only intermittent, or very low power use is required.)
To further explain - If the electricity is generated from a gasoline engine - and that energy is converted to electricity, and then sent through power line transformers and power lines, and then converted to DC, and then converted to chemical energy, and then converted back to electrical energy, and then converted to rotary mechanical energy - it is clear that many losses have occurred. If the same gasoline motor was providing the rotary energy directly to the drive train, it is much more efficient.
We can also take the cycle life of a battery times its capacity to get the total power delivered over the life of the battery. We can then look at that power as a cost per kWh and compare it with other forms of power - even this ignores the cost of the power used to charge them in the first place and it is clear that at this time batteries are not cost effective for cars.
[edit] Energy carriers vs fuels
An energy carrier is not a fuel. A fuel might be burned to activate an energy carrier. An example might help - petroleum is a fuel - it occurs as a source that is burned to create energy. Hydrogen is an energy carrier - it only occurs naturally as a burned ash - caller water - or as part of hydrocarbon fuels.
1 Venture vultures are those folks that make a living off of of the venture capital investment of folks that didn't study math or physics.
uranium as a fuel. approximately 45,000,000 Wh/l and 2,000,000 Wh/kg ????? Need a verified number??
Carbon => CO2 9111Wh/kg
Carbon => CO 6306Wh/kg
coal 1.346 g/cc
Anhydrous ammonia has a hydrogen density of 0.12 gm/cm^3
Need to figure the pressure of compressed air above.
