WiFi signals to generate Wireless Green Energy?

Researchers have developed a technology that uses the radio frequency of WiFi signals to generate wireless green energy that could power small electronic devices without the need for a battery.  

If the research of the team from the National University of Singapore (NUS) and Japan’s Tohoku University (TU) follows through the recent success in powering a light-emitting diode (LED) wirelessly to power small electronics, the need for batteries in small devices could diminish, easing the growing pressure on critical battery metals.  

“We are surrounded by WiFi signals, but when we are not using them to access the Internet, they are inactive, and this is a huge waste. Our latest result is a step towards turning readily-available 2.4GHz radio waves into a green source of energy, hence reducing the need for batteries to power electronics that we use regularly,” said Professor Yang Hyunsoo from the NUS Department of Electrical and Computer Engineering, who spearheaded the project.  

“In this way, small electric gadgets and sensors can be powered wirelessly by using radio frequency waves as part of the Internet of Things,” Hyunsoo said of the research, whose results were published in the journal Nature Communications on Tuesday.

The research team managed to overcome the spatial and low-frequency limitations of the radio frequency waves by designing an array in which eight tiny smart devices known as spin-torque oscillators (STOs) are connected in series. The 2.4 GHz electromagnetic radio waves that WiFi uses were converted—using this array—into a direct voltage signal, which was then transmitted to a capacitor to light up a 1.6-volt LED. When the capacitor was charged for five seconds, it was able to light up the same LED for one minute after the wireless power was switched off, the researchers said.

The next step for the team is to test those WiFi energy harvesters for wirelessly charging other useful electronic devices and sensors. The researchers also hope to collaborate with industry to explore the development of on-chip STOs for self-sustained smart systems, which can open up possibilities for wireless charging and wireless signal detection systems.

The implications of a potential breakthrough wireless green energy source for small electronic devices without the need for any batteries could be huge, especially in the energy transition. This transition will require increased amounts of key battery minerals to advance the electrification of transport and boost the share of renewables in electricity supply.

Since the pandemic started, calls for ‘building back greener’ have been coupled with warnings that greener economies and net-zero emissions goals will drive demand for key energy transition metals, including lithium, copper, and cobalt.

“In the transition to clean energy, critical minerals bring new challenges to energy security,” the International Energy Agency (IEA) said in its special report ‘The Role of Critical Minerals in Clean Energy Transitions’ earlier this month.

Potential supply shortages of lithium, copper, and other critical minerals would lead to rising raw material prices in the current commodity bull run. Higher prices of input metals could actually slow down the energy transition because they could slow the decline in battery costs, analysts warn.

If some part of the billions of small electronic devices in the world could be powered without the need for batteries, increased amounts of key metals could be used in the big batteries necessary to power electric vehicles and increase energy storage.

In this week’s bombshell report saying the net-zero goals will not need any new investment in oil and gas, the IEA also admitted that the accelerated path to net-zero emissions would create new energy security concerns about the supply of critical minerals, including price volatility and additional costs for transitions, if supply is unable to keep up with surging demand.