How far a car can drive based on either of the following forms of energy, each produced from 100m x 100m (2.5 acres) of land:
How come that biofuel does not really cut it? Electric cars are about four times more energy efficient than fuel based cars. This is because fuel engines mostly creates heat and thus wastes the majority of the energy units available. Combine this with biofuel plants not being very efficient solar energy harvesters relative to semiconductor based solar electricity, and the result is this huge difference.
In other words, it is clear that if the goal is to maximize energy efficiency, the end point to go after is all-electric cars everywhere. Moving all of transportation to all-electric would essentially cut in half our overall energy consumption without compromising on distance to go.
– from nanosolar