Do the costs of fossil fuels make it prohibited for common use?

Answer 1

This can be considered from what is known as a "cost-benefit analysis." It's like engineering. Most engineers are interested in developing systems that will do something in the cheapest way, consistent with safety and other concerns. (The big exception is aerospace, where cost is not as important as light weight and reliability).

Right now, our cheapest, most abundant, and portable source of energy is fossil fuels. When the use of petroleum products for fuels causes depletion that makes the price rise so that it is worth more for use as lubricants and chemicals, there will be more effort put into alternatives.

Also, when world politics (such as wars) causes an increase in prices that is high enough so that alternatives are more economical, their use will greatly increase.

The sleeping giant in this is coal, which is very abundant and could extend the use of fossil fuels for many years.

Answer 2

Apparently, not yet, but for say, 20 years, it could be different

Answer 3

I still see cars and trucks and things running out there, so: "no."