Without getting too philosophical, if energy is really what you want to work on, then the problem of making batteries that are as small and as energy dense as p

Without getting too philosophical, if energy is really what you want to work on, then the problem of making batteries that are as small and as energy dense as possible would be worth spending an entire life trying to solve, because a breakthrough in battery tech would easily have an impact on tons of unrelated industries and trigger a new technology revolution.