WhoshouldIsee Tracks

14th October 2021

Energy harvesting benefits and applications

Energy harvesting benefits and applications

What is meant by energy harvesting?

It is the ability of electronic devices, especially lower energy consuming sensors –  to exploit the omnipresent, ambient energy that is present in the environment all around in various forms: kinetic energy (movement, vibrations), thermal energy, electromagnetic wave energy and solar energy.

Some of this energy is natural such as solar, wind or the movement and heat of the human body. Other forms derive from modern but still inefficient technology invented by humans like RF waves, machine vibrations and waste heat from vehicle exhaust pipes, machines and industry.

This energy isn’t enough to power larger devices let alone huge industrial machines – but is sufficient to keep sensor networks, wearable tech and smaller consumer electronic devices working for years on end.

The technology and materials science still has a long way to go because we all still use cables to charge our phones, laptops and tablets. Our TV remotes still use batteries.

Energy harvesting will not solve the current energy crisis or heat our homes, currently only fossil fuels and nuclear power can do that on a large scale, with the future pinned on huge solar towers, wind farms and the holy grail of fusion energy.

But it can eliminate the need for constant battery replacements in up to a trillion sensors in the very near future. That is a lot of batteries no longer in olympic pool sized landfills, seeping poisons into the earth. But this extends even further: all the energy and resources needed to manufacture those batteries in the first place will no longer be needed, putting even less stress on the environment. There is a knock on effect.

Look closer to home, and namely to what we are holding in our hands for much of the day, every day. Yes, the mobile phone. Currently around 15 billion of them and only growing in number. Each phone is discarded every few years, along with the exhausted battery inside. Research is ongoing on how to harness the energy around us to power these devices, especially from high frequency electromagnetic radiation. This is one of the biggest challenges of energy harvesting as our phones also grow in complexity and power each year and so are hungry for ever greater electricity.

Why is energy harvesting important?

Look at the bigger picture, beyond the need for a battery free future. Without energy harvesting the ever larger and more complex civilization that humanity is building, reliant on ever increasing quantities of data – will be unable to function. The IoT (Internet of Things) along with wireless sensor nodes is growing exponentially and energy harvesting will make it possible to embed trillions of sensors globally that otherwise would lose power and die.

The sheer number of wireless sensors will be so huge that it will be impossible to change the dying batteries of every one of them manually, without compromising the gargantuan flow of live data for analysis. Some will be so remote so as to be virtually inaccessible – deep underwater or underground, among the clouds, on top of icy mountains or in dark jungles or forests . Even near volcanoes or inside nuclear reactors.

Nowhere on Earth will be sensor free in the information age and coming intelligence explosion. And all those sensors may not even be distributed or embedded by human hands, perhaps ‘sown’ by swarms of drones into the environment. Obviously biodegradable and plastic free.

How does energy harvesting work?

By utilising an ultra-low power highly integrated mixed signal system on chip (SoC) along with a combination of piezoelectric transducers, thermoelectrics, solar cells and antennas combined with rectifiers to create electric current to power sensors, wearable tech and standalone consumer devices that can all operate on low power. The key point here is that these devices can pause their operation during lulls in ambient energy and begin operating again when that energy returns.

Kinetic energy and Piezoelectrics

Kinetic energy derives from movement and vibrations all around us, mostly from the machines that we use as well as our own bodies. Other sources include acoustic noise, sounds from heat waves, motor bearing noise from aircraft wings and car tyres.

This energy can be harnessed in devices and sensors with built-in piezoelectric materials that when subject to stress or environmental vibrations generate an AC voltage proportional to the applied stress.

There always comes that infrequent but annoying moment when the remote control for our TV stops working. We hunt for a small battery that we either can’t find or don’t have at home. These days many of us are using Amazon’s Fire TV Stick with Alexa Voice Remote. In addition to Alexa, wouldn’t it be useful to also have a piezoelectric energy harvester that will make use of the thousands of times our thumbs press the home button, storing that energy in a flexible capacitor? Then again, will voice assistants not render buttons obsolete in the future? Perhaps for some people, but the kinetic energy option will always be there. After all, not everyone can speak. Or even want to.

Movements and motion generated by humans can be harnessed by walking on floor tiles, pressing buttons, using exercise machines, stretching in the gym while wearing garments embedded with energy harvesters and more.

Imagine the smart city of the future. As you walk everyday through the streets to and from work, visit a shopping centre, railway station, sports stadium or other site with large crowds of people you will be adding to the footfall in these highly visited venues. A steady stream of kinetic energy from the city’s inhabitants.

You could wear a piezoelectric object on your knees harvesting energy for your wearables as you walk along a piezoelectric walk-way. On the nearby grass a glittering piezoelectric tree or sculpture harvests energy from turbulent wind generated by soaring skyscrapers.

The electric cars moving quietly around you will have piezoelectric pressure sensors built into their tyres, improving efficiency. That bridge you just walked across will have countless sensors constantly monitoring the stresses at play.

The huge office building you work in will have hundreds if not thousands of light switches all harvesting millions of thumb or finger presses each year.

One of your older work colleagues has an implanted electrocardiogram (ECG) sensor harvesting energy from her heartbeats, enabling remote patient monitoring.

But there is more. In addition to harvesting energy in the mega city of the future, all these devices will enable the city authorities to detect the live mode of transportation that users are in. This is because each mode of transport be it walking, running, car, bus or train has a different vibration pattern and generated AC voltage. Harnessing both the data and kinetic energy from countless sensors will help cities not only reduce battery drain but perfect urban designs.

One such company helping to make the smart city of the future a reality is global technology company ZF. They have integrated a kinetic energy harvesting switch in pushbuttons for stop request bells in buses, developed smart window handles for homes and buildings and an innovative wireless push button module used for KNX lighting control at Beijing Airport.

Thermal energy and Thermoelectrics

Thermal energy is all around us, from what we feel immediately in our bodies, as well as from the sun and geothermal sources in the natural environment. It is consumed and wasted in huge amounts by the machines humans use in technology and industry.

Think of the vast data centers that operate in cold regions of the earth so as to avoid overheating. A relatively recent development in the world of tech and constantly growing to house exponentially growing “mountains” of data. So-called Big Data – much of it based on our lives in social media.

It is also present in the air molecules that continuously fly around us even on a calm day with not a breeze in sight. Scientists are working on nanomachines that will harvest this energy, but that is the future.

What small or low powered devices can make use of thermoelectric materials that convert lower thermal energy into electricity? Already wireless sensors embedded in high powered industrial areas make use of the surrounding heat.

Low-power thermoelectrics on the other hand will be flexible, stretchable, implantable and wearable: designed for healthcare, consumer wearables and IoT. They will exploit heat from the human body and be used in MEMs or Micro-electromechanical systems that include blood and biosensors.

Electromagnetic energy (RF, T-rays)

Why not exploit all the invisible electromagnetic (EM) radiation whizzing around us in space originating from TV, radio and mobile phone towers to name a few?

Rectennas can harvest stray radio waves and even higher frequency EM radiation can be exploited using a Nantenna.

Terahertz radiation or T-rays have the potential to extend the battery life of the powerful computers that most of us carry around with us all day, namely smartphones. Material scientists are exploring whether graphene devices can help us harvest this untapped gold mine.

Solar/Light energy - Photovoltaic cells

Aside from the massive scale of electricity generation from vast Spanish solar towers and their surrounding arrays of photovoltaic panels, small solar cells have powered our electronic calculators, toys, garden fountains and other devices for years. This is nothing new.

But thanks to advances in computing and low energy management solar energy harvesting can now be extended to wireless sensor networks inside buildings where the ambient light levels are low.

Applications include wireless sensors for smart homes, building automation, presence detection, remote monitoring and industrial equipment controls as well as fitness sensors and wearables.

The future of energy harvesting

The field of energy harvesting is set to grow massively, spurred on by climate change, extreme weather events and the current energy crisis in Europe, indeed across the world. We can no longer rely on fossil fuels, even though the brand new Nord Stream 2 pipeline is now “all systems go” for colossal Russian gas imports into energy hungry Europe. This enormous project will surely rely on countless remote sensors though, some perhaps harvesting water currents deep in the Baltic Sea.

Smart cities, building automation, autonomous vehicles, telehealth and agricultural IoT will drive the number of connected devices to over 21 billion in 2025.

We are standing at a crucial fork in the road and harvesting both the natural and wasted energy from civilization all around us will lead us down the right path to a bright future.

Contact us to discuss how ZF energy harvesting could help you Contact us