There is another huge issue with capacitance storage, that I'm surprised the article doesn't mention. Capacitors store potential. More energy is stored as more potential...ie voltage. So a Ultra-capacitor is also an ultra high voltage device. When you discharge them you need to be able to convert this ultra high voltage to a useable level. You also have one Ultra dangerous device capable of giving 10,000 volt shocks. The rule is "current kills" but voltage gives it the ability to do so.