Charging into the future

Energy storage is often seen as the most important missing part in the electricity infrastructure of many countries, not least the UK. The main reason for this is renewable power. Wind, solar and marine energy (wave and tidal) have the potential to generate large amounts of electricity, but being dependent on natural processes they are not predictable and sometimes occur at periods diametrically opposed to when they are needed – for example, the sun shines during the day but we switch our lights on at night. Being able to store the energy in times of plenty – when it’s windy, sunny or the tide is coming in or going out – and then release it to the grid when it’s needed would allow renewables to be used to their full potential, and further reduce our reliance on fossil fuels.

There are many ways to store energy. Pumped storage, where water held in a reservoir at a high altitude is allowed to run through a turbine flowing down to a lower reservoir, is among the most reliable and is used in the UK, Scandinavia and elsewhere. Compressed air storage is also increasingly scrutinised, as is using surplus electricity to liquefy air so that it can be allowed to evaporate through a turbine (Highview Power, a pioneer in this field, is a previous winner of an Engineer award for innovation). The so-called hydrogen economy, where surplus electricity is used to electrolyse water, and the resulting hydrogen stored to be converted back into electricity through a fuel cell, has been touted as a solution for decades. All of these systems have been covered by The Engineer.