Gravity Batteries: Making Renewable Energy Viable

Kenton Reynolds, Writer
@uxconnections

A new concept for batteries that store gravitational potential energy could be a solution for a key issue with renewable energy sources.

Renewable energy is gaining popularity with renewable-only companies like Octopus growing rapidly; more businesses introducing production from renewable sources; and more businesses providing consumers with a choice of renewable energy. However, as usage increases the problems that are a part of renewable sources become more pressing.

One of the key issues with renewable sources is their unpredictability. With finite sources such as nuclear and fossil fuels we can control production levels in order to keep up with the peaks and troughs of demand. With fossil fuels we burn more to produce higher amounts of energy and with nuclear reactors, control rods are removed to increase the number of reactions taking place during peaks like the ones seen in Winter where more people are indoors with heating. Renewable sources, on the other hand, rely on external factors that cannot be controlled. Solar energy cannot increase for winter demand, in fact it will be at its lowest. Wind generated power relies on strong winds and on still days will produce very little. On the other extreme, we may have extremely sunny days or windy days when usage is low. In these periods, more energy is produced than we need and this excess is wasted.

Being able to store this excess energy would make renewable energy a much more viable option and see it replace less environmentally friendly sources quickly. If we could store this huge amount of energy in some form of battery which could then release it when it is needed, we would have an excellent energy solution to increase production during demand peaks or during low production periods.

The International Institute for Applied Systems Analysis have presented a promising solution to this problem: gravity batteries. They propose to use decommissioned or abandoned mines – of which there are countless worldwide – to be repurposed into batteries that store excess energy.

The batteries can be made of anything heavy whether that’s water or a solid object. In the vertical mineshaft, the excess energy is used to lift the battery and hold it at a height which transfers the electrical energy into gravitational potential energy. These batteries, unlike the ones we have now, are able to store this energy for as long as is needed and do not discharge over time. When electricity is needed, the batteries are dropped to transfer kinetic energy which will turn a turbine and then produce electricity. Researchers have said that a $1-10 per kWh investment alongside a $2000 per kW power capacity cost, there is a potential for up to 70 tWh globally which is higher than the 68 tWh global average usage in 2020.

Abandoned mines are ideal for this task with there being over 2000 in the UK and likely millions across the globe which are already containing at least some of the infrastructure required as well as being connected to the power grid. In addition, the closure of mines is usually met with opposition due to the loss of jobs that it creates but this could bring some of those jobs back in that same geographical area.

Gravity batteries could be an excellent solution to some of the issues that renewable energy is facing whilst creating jobs in areas that have faced unemployment in the past.