Explainer: storing renewable energy

By Maria Skyllas-Kazacos on 3 July 2012

Storage is one of the highest technological barriers to the spread of renewable energy. When the sun is shining, the tide turning or the wind howling, how do we collect that energy and keep it to use when generation is down?

There are many different types of energy storage technology available or under development. But each technology has some inherent limitations or disadvantages that make it practical or economical for only a limited range of applications.

Some technologies are mechanical (flywheels, pumped hydro, compressed air). These have low energy efficiencies and slow response times. Pumped hydro and compressed air storage systems are also restricted by special geological and geographical requirements, high investment costs and long construction times.

Electrochemical energy storage systems – batteries – offer many benefits and advantages compared with other forms of energy storage.

Amongst the different types of battery technologies currently available, the ones receiving the most attention for large-scale energy storage applications are: – lead-acid – lithium-ion – sodium sulphur – flow batteries.

Lead-acid batteries

Lead-acid batteries are low cost. But their application for large-scale energy storage is limited by their short cycle life and limited rechargability