Yea, there are bunches of things. How about cold fusion? There was a buzz a few years back, maybe decades back as I'm getting old. It was an interesting concept and there's no reason to believe their failure means you won't succeed (that sounds like a double negative...) On that topic, how about incremental improvements to solar energy collection? Maybe not as glamorous but sorely needed. How about energy storage? Better batteries possibly or other storage paradigms. How about energy efficiency improvements? Save a few watts times a billion users would be significant.
Another topic which strays more to the math of things is artificial intelligence. There's lots of room for innovation in AI.
A lot of new design is built on other's innovations. For example, 3 D printing is opening up new possibilities in manufacturing that in turn can lead to new designs.
I got more verbose than I intended. It's not all done! There's a boat-load of possibilities.