It doesn't have to be that way. 70% of Earth's sun absorbing surface is unused saltwater. Most people don't know this but all the energy in petroleum originally comes from saltwater algae. With bioengineering it should be possible to create super-algae that can be converted efficiently into bio-diesel and alcohol fuels. It's a bit silly to consider but the oceans are so vast we could breed whales to eat the algae/plankton mix then swim their oily selves to the coasts for conversion to fuel. Most of our transportation fuel use is near the coasts. The good thing about making our own petroleum is it would create a CO2 closed loop system allowing nearly unlimited economic expansion. Saltwater algae or some kind of saltwater plant seems to me to be the most promising direction.
About plug-in hybrids: why not embed electric lines in the road beds of highly traveled freeways and use induction to transfer the power? The hybrids then would not need heavy batteries which would noticeably increase mileage. When the car brakes it could sell the power back to the grid. These cars could be hooked up into virtual trains boosting freeway lane capacity by 10. We'd get all the benefits of commuter trains with the personal freedom of automobiles.
That’s why I said “currently made from food crops”.
Yes, algae is promising as a bio-diesel source. I wouldn’t go the whale route. I like whales.
You would think that since power lines already run alongside most roadways, that an inductive pickup would be a no-brainer. Maybe it is, or maybe the difficulty in metering the usage per vehicle would be very expensive. Or maybe allowing inductive taps would allow too high a bleed loss even when there is no vehicle around. It isn’t really necessary in the cities, anyway, since battery tech is already good enough for short distances. Where you really need it is on the long stretches between cities, but the traffic density on those stretches may not justify the cost in infrastructure.
I like the idea of cars tailgating with their braking and acceleration coordinated by computer to form “Trains” on the road. It would fit more traffic on the same highway and use less energy because wind resistance would be less. Can’t be done until a significant numbers of vehicles are designed to take advantage of it, though. Vehicles joining and separating from the “Trains” becomes a problem, especially when there is an entire train of vehicles in the lane you need to move into. Instead of finding a space between two 20ft long vehicles, now you have to look for spaces between 200ft long trains of ten vehicles each.