What is a bad thing about hydrogen fuel cells?

One bad thing about hydrogen fuel cells is that hydrogen is a highly flammable gas. This means that there is a risk of fire or explosion if hydrogen is not handled properly. Additionally, hydrogen is difficult to store and transport, as it is a very low-density gas. This means that it takes up a lot of space and is difficult to move around. Finally, hydrogen is a relatively expensive fuel to produce, as it requires a lot of energy to extract from water.