The notion of mobility is complex. As human beings we are mobile by design. We are autonomously mobile, we move by our intent. As human beings we also create tools to enhance our mobility. From the invention of the wheel, to the rickshaw, bicycle, the horse drawn carriage and ultimately the automobile, mankind has created tools to increase his mobility.
According to mobility expert Dan Sturges, before the Model T, most Americans lived their entire lives within a 30 mile radius of their birthplace. Something we can hardly imagine in today’s reality.
Mobility or transportation is the expending of energy to move a person or thing from one place to another. It is relentlessly governed by the relationship
The amount of energy expended is equal to the mass to be moved and the speed at which is must be moved during a time period. So for a fixed mass, and a fixed amount of energy you can either go really fast for a short distance, or you can go slower for a long distance. That’s how it works when you are looking at the stored energy part of the equation.
So my MIP mobile “toy” robot can run for quite a while on 4 AA batteries. Same for BB8. They are just toys, they only have to transport themselves. MIP can carry a cellphone around. The cellphone weighs almost as much as MIP does. The total distance MIP can travel will be about half the distance without the cellphone.
That’s the analogy you have to think of when considering things like mobile robots and electric cars. How much energy can you store, how much does it way, how much does the drive train weight, how much load can it carry, how far can it go? These are the metrics of self powered systems. The big hang up is energy storage. Gasoline stores about 31 kilowatts per gallon which weighs about 6.2 pounds. The Tesla Powerwall has a published power rating of 3 kilowatts and weighs 220 pounds.
Of course, the energy in gasoline burned in a car engine is mostly wasted as heat. This is compounded by the loses in the drive train of the a car, making it likely that only a few percent of the energy in gasoline actually gets turned intro transportation.
Each form of transport system has range and power requirements based on the mass and speed of the system. This sets the requirement for power storage. So we always come back to the same issue. In spite of the progress made over the last 20 years in battery technology, we still need to move the density one more order of magnitude to unleash the age of electric transportation.