Viability of supercapacitors for energy storage to mitigate renewable energy sources intermittency

Abstract

Energy storage is seen as a solution to assist in the integration of renewable energy by meeting intermittency. Such energy sources suffer from the widely known obstacle of intermittency. To overcome this issue, a formidable energy storage system is required. While large scale energy storage systems such as pumped-storage schemes and compressed air energy storage systems exist, renewable energy sources such as solar and wind power use batteries as a form of energy storage. Additionally, these large scale energy storage systems suffer from a number of drawbacks such as specific location and geophysical requirements. Photovoltaic arrays and wind turbines almost exclusively use batteries as the preferred method of energy storage. Recent years has seen a surge in the advancement of supercapacitor technology. The two main characteristics of supercapacitors are: high power density and low charging time. This has drawn considerable attention to the technology and has thus been implemented in electric buses and hand tools. Other desirable characteristics, as compared to electrochemical batteries, include: smaller weight; lifespan and fewer toxic materials. The last characteristic mentioned is of notable concern since lead-acid batteries are known to emit dangerous gases such as hydrogen and also use sulphuric acid and lead in their production which can lead to laryngeal carcinoma. Latest developments have seen an increase in the overall capacitance (and decrease in cost price) of supercapacitors which may allow supercapacitors to be used as energy storage system, either in a stand-alone or hybrid capacity or both. This study attempts to prove that supercapacitors can replace electrochemical batteries on a domestic scale through simulation where the number of supercapacitors required to supply a domestic load for 24 hours is determined. The time required to charge these supercapacitors is also ascertained. However, it was found that supercapacitor technology is limited to smaller applications or a hybrid design working in conjunction with batteries as protection surge currents.