I think you need to have a think about something you find interesting or important, and develope a concept for it. The strongest works are those with a great story and then you don't need to create a brilliant technical piece.
Difficult subject actually, as you can imagine quite a lot of things will be possible but aren't at the moment. Can you do that aswell?
You could try and find something you really don't agree with; politics, science, etc and come up with an interesting twist. For example, and pardon the stereotype, strongly religious people are against abortion or manipulated conception (IF treatment). From that point of view you could create a tree that grows babies and your concept could be that you want to show something that is impossible but that in it's essence already happens but in a different way. Cloning would probably be an easier example. Or you could create a printer that prints tomatoes. With the current genetic manipulation they might aswell. The picture is impossible but the actual meaning is very valid and critical.
