Question

Please help!
compare the pros and cons of a fuel cell, such as the hydrogen_oxygen fuel cell, and a coal_fired power station for generating electricity.

Answer 1

Nobody would replace a coal-fire power plant with a fuel cell plant. The equipment for the latter would be fabulously expensive, compared to the former. That would be like replacing the metal gears on your bike with gears shaped from pure diamond. Sure, it'll work -- but the cost is crazy.

Where a fuel cell makes sense is as a small mobile power plant, like for a spacecraft (where they are indeed common), or automobile, or electronic device, where the least possible weight for the power plant is important enough to justify the considerably greater expense of the fuel cell.