Virtually every story needs some kind of conflict and tension. They spice things up and make the story more interesting to readers. You can find them in the earliest children's books. Conflict, and its resolution, is what makes people want to turn the page to see what happens next. Conflict can occur between many aspects of a story.
Conflict can even occur between one character.
I want to do it, but I know I shouldn't, but I can't help myself. Giving deadlines, like with the bomb timer above, can create tension. A deadline for a project, something that must be done before the eclipse is over, the floodwaters are rising, a tsunami is approaching and so on. Tension can also be created when nothing is happening. Tension can also be created with fast action, when disaster can happen at any moment.