A short-sighted comparison of only the gas tank and battery was deemed insufficient, as Argonne researchers discuss the importance of powertrain efficiency as well as the mass of the powertrain itself.
It is predicted that by 2045, similar to gas-powered vehicles, battery electric vehicles will offer the same amount of energy spent at the wheel per kg of the powertrain mass. If gas and electric vehicles have the same energy density, this means the vehicles have the same amount of energy in a given system per unit of volume or mass.
Until electric vehicles reach that point, it stands that gasoline is 100 times more energy dense than a lithium-ion battery. This means that it would take a lot more pounds of battery to go the same distance in a vehicle than pounds of gasoline.
Argonne rests their case by encompassing other factors that suggest future technological development. Significantly, the energy needed to go a particular distance in an electric vehicle is less than that of a gas vehicle. During the conversion of fuel into motion, all-electric powertrains lose less energy than gasoline engines.
While an electric powertrain is often times more than 90% efficient, less than 20% of the energy stored in a gallon of gas is converted into mechanical motion. The actual transfer of power through the transmission and to the wheels suffers a great mechanical loss in gas powered vehicles.
In this regard, electric vehicles pose a solution to maintaining a greater amount of power over a distance. Of course, an analysis as to whether electric cars would continue to be a costly alternative has not been completed.