Capacitors are great for high load requirements but not great as an energy storage device. i.e. if you wanted to draw several hundred amps for a second or two with relatively low heat waste, an ultra-capacitor arrangement would be the way to go, but for energy storage, a battery wins hands down. There's huge research going into expanding the capacity of capacitors.

Check out this video about capacitors: https://www.youtube.com/watch?v=EoWMF3VkI6U