The state's combination of abundant renewable resources, high fuel prices, limited geographic area, and recognized expertise in hydrogen technology R&D, makes it an ideal location to lead the state's transition to a renewable energy-to-hydrogen economy. By attracting considerable investments of capital and expertise to Hawaii, we will be investing wisely for our future needs.

Ted Liu

Super Capacitors

A capacitor is an electrical device that can store electrical energy. Energy is stored in the electrical field between a pair of closely-spaced conductors or plates when voltage is applied to the capacitor causing electric charges of equal magnitude, but opposite polarity, to build up on each plate. A capacitor can store electric energy when disconnected from its charging circuit, so it can be used like a temporary battery.

A supercapacitor or ultracapacitor is an electrochemical capacitor that has an unusually high energy density when compared to common capacitors. They are of particular interest in automotive applications for hybrid vehicles and as supplementary storage for other types of electric vehicles. Such energy storage has several advantages relative to batteries:

• Very high rates of charge and discharge.
• Little degradation over hundreds of thousands of cycles.
• Good reversibility
• Low toxicity of materials used.
• High cycle efficiency (95% or more)

Disadvantages:

• The amount of energy stored per unit weight is considerably lower than that of an electrochemical battery (3-5 W.h/kg for an ultracapacitor compared to 30-40 W.h/kg for a battery). It is also only about 1/10,000th the volumetric energy density of gasoline.
• The voltage varies with the energy stored. To effectively store and recover energy requires sophisticated electronic control and switching equipment.
• Has the highest dielectric absorption of all types of capacitors.