Reflect on what might happen next. One writer speculates about the future in her informative essay.

It is certain, though, that at some point, the fossil fuels that have sustained our society’s electricity and run our motor vehicles for over a century will run out — or become so expensive that they’ll no longer provide an economically viable source of energy. Whether that day comes in five years or fifty, we need to shift to a new energy source — one that is practical, economical, and environmentally friendly. Hydrogen has demonstrated great promise as a new candidate for fuel. To realize that promise, however, we must work to remove the barriers that currently prevent hydrogen’s emergence as a mainstay of our future economy.