If you mean the most energy per unit weight of the fuel, this is uranium at present. In the future if nuclear fusion can be made to work, this will provide even more per unit weight (by unit weight I mean per gram or kilogram).
On the other hand if you mean the most total energy as used world wide, this must be oil, as it is used so widely in transport. In terms of electricity coal is still the largest single provider of electric energy.
You can see that in posing such a question you need to be more precise. What does 'most' mean, and what types of energy do you include?
Electricity is the most versatile, but not usually the cheapest. For home heating, natural gas if available.
Cut out unnecessary energy waste by improving energy efficiency.
Whatever kind is available that you already know how to use, until something else can be developed. Then you use that.
Simple sugars are used for immediate energy conversion in most living things.
Cells use ATP (adenosine triphosphate) as their immediate energy source.
glucose
fat
glycogen
Carbohydrates are the body's primary and immediate source of energy.
Carbohydrates are the body's primary and immediate source of energy.
Carbohydrates usually provide immediate energy to the body.
Simple sugars are used for immediate energy conversion in most living things.
Cells use ATP (adenosine triphosphate) as their immediate energy source.
The Immediate Energy System provides energy rapidly but for only a short period of time. It is used to fuel activities that last for about 10 or fewer seconds.
energy expendature > energy intake. there is no super secret way to lose weight and this is pretty much the only option.
glucose
Glycogen
The use of force to prevent an attack in a situation where immediate action is the only possible option
Tidal and wave energy is best suited for generating electricity, which will then power just about every device on earth. Flour mills powered by paddle wheels in rivers were the only other immediate use of water energy in the past.
glucose