In large scale systems such as solar and wind farms of the future, huge amounts of storage capacity will be vital for times when the wind doesn’t blow or the sun doesn’t shine so that the mains grid can receive a continual supply. The two solutions currently with the best potential are molten salt storage systems and ultracapacitors; also known as super capacitors.
Engineers and scientists at The University of Texas at Austin recently announced a breakthrough that may lead to the ability of storing massive quantities of electricity in ultracapacitor devices.
The researchers have been investigating the use of a one-atom thick structure called "graphene" (a form of carbon) that could double the capacity of existing ultracapacitors which currently use an entirely different form of carbon.
According to Rod Ruoff, a mechanical engineering professor and a physical chemist on the team, ""Graphene’s surface area of 2630 m2/gram (almost the area of a football field in about 1/500th of a pound of material) means that a greater number of positive or negative ions in the electrolyte can form a layer on the graphene sheets resulting in exceptional levels of stored charge."
This technology has the potential to not only store electricity for renewable energy systems, but significantly improve efficiency and performance of electric and hybrid cars and other forms of transportation, along with smaller devices such as office and communications equipment.
While deep cycle batteries are the most popular way to store electricity generated by renewable energy, ultracapacitors are becoming increasingly commercialised; but at this point mainly for high-end industrial uses or for small electronics – it will still be some time before ultracapacitors are made available for applications such as home off grid solar power systems.
Advantages of ultracapacitors over deep cycle batteries include: higher power capability, longer life, a wider temperature operating range, lighter, more flexible packaging and lower maintenance.