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Energy densities of various fuels.
Sat Oct 7, 2017 10:42pm
2602:30a:2c0c:99d0:e44d:bdd5:5fac:1d9

The merest glace at this table shows why the electric airplane isn't going anywhere for a LONG time, if ever. We need a whopping 25-fold (probably impossible) improvement in battery performance to do this.

Sure, small aircraft & RPVs fly around on batteries, but none of them is about to carry 300 passengers from New York to London.

Jet fuel (JP): 42.8 megajoules per kilogram
Lithium metal-air battery (Li-O2): 1.8 megajoules per kilogram

An airplane using JP gets lighter as it flies as fuel is consumed combines with air to form water and carbon dioxide, both of which are expelled.
On the other hand, an airplane using Li-O2 battery gets heavier as the fuel is combined with oxygen from the air to form solid lithium oxide which is retained within the battery.
That makes the comparison even more favorable to JP as opposed to Li-O2.

People are surprised to note that TNT contains about one ninth as much energy per kilogram as JP (4.6/42.8). This is for two reasons:
1. TNT carries its own oxygen, which adds to the weight.
2. TNT has a poor oxygen-balance, that is, it produces much unburned carbon and carbon monoxide.

If TNT is burned in oxygen or air, heat of combustion is 14.5 megajoules per kilogram, because of the additional energy liberated as un-combusted reaction products are burned. In general, explosives do not contain more energy per kilogram than ordinary fuels, but release the energy that they do contain much faster.

I also remember fairy tales from the past where cars would be driven around on super-capacitors. One look at the chart shows what folly this is.

The numbers in this table are absolute and cannot be altered (except slightly by different formulations).

Storage material Energy type Specific energy (Megajoules/kilogram) Energy density (Megajoules/Liter)
Alkaline battery Electrochemical 0.5 1.3
Butanol Fuel Chemical 35 36
Carbohydrates (including sugars) Chemical 17 13
Coal, anthracite Chemical 26-33 34-43
Coal, bituminous Chemical 24-35 26-49
Diesel Chemical 48 35.8
Dimethyl ether (DME) Chemical 28.8 19.3
Electrostatic capacitor Electrical (electrostatic) 0.00001-0.0002 0.00001-0.001
Ethanol fuel (E100 gasoline) Chemical 26.4 20.9
Fat (animal/vegetable) Chemical 37 34
Gasoline (petrol) Chemical 46.4 34.2
Gunpowder Chemical 3 3.5
Heavy fuel oil (HFO) Chemical 41 31
Hydrogen (compressed at 700 bar) Chemical 142 9.17
Jet fuel (Kerosene) Chemical 42.8 37.4
Lead-acid battery Electrochemical 0.17 0.56
Liquefied natural gas (LNG) Chemical 53.6 22.2
Lithium metal battery (rechargeable version in development) Electrochemical 1.8 4.32
Lithium-ion battery Electrochemical 0.36-0.875 0.92.63
LPG (including Propane / Butane) Chemical 46.4 26
Methane or natural gas Chemical 55.5 0.0364
Methanol fuel (M100) Chemical 19.7 15.6
Nickel-metal hydride battery Electrochemical 0.288 0.5041.08
Protein Chemical 16.8 12
Super-capacitor (EDLC) Electrical (electrostatic) 0.01-0.036 0.05-0.06
TNT (detonation without combustion) Chemical 4.6 3.2
Wood Chemical 16.2 13


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