Energy yield of fuels
Mineral oil and her derivatives like petrol and petroleum are part of our "normality" as fuels.
Unlike with food we will never know exactly how much energy it took to make many of these energy sources. Especially mineral products that are mined. Luckily the Binas - the Dutch high school scientific reference handbook - tables just give the exact combustion per litre value. The values from Binas have been recomputed to contain the energy per 100 gram. This is unusual when we deal with petrol, because now we are used to measure this fuel in litres, but you'll get used to it. Anyway, a lot of substances are 1 litre /1 kilo. Check it out for yourself in Table 3.
|Scale||Examples of fuels. Energy return on combustion||Red|
|5||brown coal, methylated spirits||R 5/8|
|6||methanol, ethanol||R 6/8|
|7||alcohol, hard coal||R 7/8|
|8||Sunflower Oil Reference Index||R 8/8|
|9||natural gas||R 9/8|
|10||petrol, butane , oil (reference TOE)||R 10/8|
|11||acetylene, propane||R 11/8|
It's remarkable how our daily fuels are a lot more energy-rich than sunflower oil, from scale 8 and up. We also see that the Swedes who commonly use spirit to cook when on holiday have to wait a lot longer for their food to be cooked. The popular Campingaz brand sells butane and nowadays the more powerful propane. Truck drivers and sales representatives will no doubt recognize the power of diesel. The huge potential of this fuel is almost double (14/8) of sunflower oil. In Euro, diesel is cheaper than Diesel, but in Red diesel is 40% more expensive.
Table 3 only shows an R-value. In contrast to food these fuels aren't really recyclable, considering you burn fuel. When we talk about bio-ethanol, it's recyclable and so Green 1. The other fuels are in principle Blue 1.
The value for oil in scale 10 is based on another standard, Ton of Oil Equivalent (TOE). This is an industry standard of 41,868 GJ per ton. This is the same as 1.23 times the energy in 1000 kilograms of sunflower oil. The difference is only 2%. That means that all products should be in the same scale as in the sunflower oil index.
Is 1/8 not accurate enough?
A more accurate scale is possible to split up the vegetables in scale 1 into vegetables 1/8, 1/16 and 1/32 of the index. It remains to be seen if this makes sense or only contributes to make things more complex. For now we didn't go into that question. We're already happy when we can illustrate the difference between Red, Blue and Green and are able to separate energy-rich from energy-poor products. Splitting energy poor products from even more energy-poor products doesn't seem relevant at this stage, and so it's not worth the trouble of calculating.