Can self-charging batteries keep us connected for ever? A young scientist explains

As part of a series exploring the bold new frontiers of science, we caught up with Mahyar Shirvanimoghaddam, expert in electrical engineering at the University of Sydney and World Economic Forum Young Scientist, to find out why he dedicated his research to creating self-charging batteries that keep our smart devices permanently running.

What is the big problem you're trying to solve?

With the rise of 5G and Internet of things (IoT) technologies, we will soon be surrounded by tiny sensors and smart devices constantly monitoring our environment and potentially changing it to improve our quality of life.

The whole process of collecting data, communicating with the cloud services, storing and analyzing it at servers is energy-hungry. We will soon have more than 50 billion smart devices, most of them installed in hard-to-reach areas, and regular battery replacement and maintenance are infeasible.

The trend so far has been to improve battery efficiency and have smaller yet more efficient batteries to increase lifetime of the devices. Despite all the improvements, for many applications batteries remain a challenge. In fact, battery-enabled smart devices have limited lifetime or longer lifetime with limited performance. There is a trade-off between the device life expectancy and the amount of energy it is using. The higher the energy it uses, the higher the performance but the shorter the lifetime. Even if we could replace batteries, what would we do with all the discarded ones?

What is the big idea you're trying to use to solve it?

In many IoT applications, devices need to be powered in a self-sufficient and sustainable fashion. A viable solution is to scavenge and harvest energy from the environment and then provide enough energy to the devices to perform their operations. This will significantly increase the device's lifetime and eliminate the need for a battery as an energy source.

An energy harvesting-enabled smart device has potentially unlimited lifetime. A device can be used for long time without maintenance or battery replacement. We have mostly been using renewable energies on a large scale: why not using them on a micro level?

We are using piezoelectric material (which generate an electric charge in response to applied mechanical stress) to convert tiny movements to electricity and store it in batteries and super-capacitors. Using a hybrid of energy harvesting techniques such as solar, mechanical, thermal, etc., could significantly increase the lifetime of IoT devices and reduce their carbon footprint.

How would you explain that to a five-year-old?

Our phones and toys all work with batteries which store energy to enable them to work. But batteries have a limited lifetime, which means we need to replace or recharge them. Imagine that we have 100 or 1,000 devices which all operate with batteries. It is almost impossible to replace or recharge all these batteries. A way to solve this problem is to use the energy available around us. We can convert almost any type of energy into electricity and store it in a battery - that would let the device work for a long time without needing to replace its batteries.

What has been the most challenging part of the journey?

Harvesting energy from the environment is unreliable. The amount of energy generated in unstable too. This makes the design very complex as the device cannot be directly powered by the energy generated from energy harvesting techniques. An energy storage unit or a super-capacitor with a power management unit should be used to store the collected energy and use it appropriately. Batteries require a certain amount of energy to be able to be recharged. There is a problem with the size and storage capabilities of the batteries which make them incompatible with most energy harvesting techniques. Price is another factor.

What do most people not know about batteries?

There are about 4.7 million developers in the world who can create IoT devices, and the number is increasing at a rate of around 3% per year. Recent studies showed that more than 3 billion batteries are discarded in the US every year, and the penetration of IoT technologies in every sector will exacerbate this problem.