Building a sustainable connected world with energy harvesting technology

The battery challenge in sustainable development goals 

In today’s sustainability-conscious world, companies, consumers, and countries are striving to address the growing energy demands driven by increasing urbanization. Achieving carbon neutrality has become imperative, making it essential to adopt technological solutions that minimize waste and deliver energy-efficient benefits. IoT applications are now challenged to embrace this transformation. 

When we think of IoT, we envision a seamlessly connected world powered by smart, innovative devices. But what keeps these devices connected? The simple answer is a power source, typically, traditional batteries. While batteries serve their purpose, they come with significant drawbacks. 

Statistics reveal that over 15 billion used batteries end up in landfills annually, releasing approximately 900,000 tons of hazardous waste that pollutes soil and groundwater. In the U.S. alone, the average household purchases more than 90 batteries each year, most of which fail to last even a decade. By 2025, an estimated 25 billion IoT devices will be in operation, requiring 6 million battery replacements daily. 

These figures highlight three major issues with traditional batteries: inconvenient and improper disposal practices, incessant replacement needs, and scalability challenges. These shortcomings not only impair device functionality and reliability but also hinder the transition of smart IoT applications toward a battery-free, energy-aware future. To address these challenges and mitigate the environmental threats posed by an increasingly connected world, a new class of connected devices has emerged - collectively known as Ambient IoT. 

Ambient IoT refers to IoT devices powered by naturally available energy sources such as magnetic and electric fields, light, heat, kinetic energy, and sound. This method of extracting operational power from ambient energy eliminates the need for batteries in IoT devices. 

With Ambient IoT, smart devices can now rely on natural energy sources for power and connectivity instead of conventional batteries. These sources (e.g., light, heat, motion) extend device lifespans while significantly reducing the environmental impact of batteries. 

Innovative wireless system-on-chip solutions for energy harvesting 

Silicon Labs is a leader in innovation and IoT connectivity, with a mission to empower developers to create wirelessly connected devices that transform industries, grow economies, and improve lives. Silicon Labs has now optimized its xG22 series of SoCs (System-on-Chip) to incorporate energy harvesting capabilities. The new energy-optimized xG22E SoC family meets all the energy conservation needs of IoT devices. 

These power-packed MCUs feature an 8ms Power-on-Reset (PoR) that consumes just 150 microjoules (µJ) and an EM4 wake-up time of 1.83 milliseconds with only 16.6 µJ energy consumption. Additionally, they deliver high RF performance, multi-protocol support, and 2.4 GHz operation. They also support multiple power sources and power management devices, enabling users to explore new battery technologies like supercapacitors. 

Take the EFR32xG22E as an example: it offers ultra-fast, low-energy cold start, low-energy deep-sleep wake-up, and efficient energy mode transitions that mitigate harmful current spikes and protect energy storage cells, making it one of the most reliable wireless long-range SoCs on the market. 

Common applications of the xG22E SoC include smart home and appliances, gaming electronics, and smart buildings. For instance, in Zigbee-enabled smart home devices like doors, faucets, and switches, energy harvesting generators can eliminate battery dependency and replacement costs. In gaming electronics, indoor solar-powered TV remotes and computer keyboards require energy-efficient and cost-effective Bluetooth LE SoCs. In smart buildings, kinetic pulse harvesting for battery-free doorknobs and light switch controls using xG22E Zigbee Green Power reduces the need for frequent battery replacements. Other key applications include tire pressure monitor sensors, asset tracking, electronic shelf labels (ESLs), factory automation, predictive maintenance, and agriculture. 

Innovative advanced energy harvesting shield kit solutions 

To help device manufacturers build complete energy harvesting solutions, Silicon Labs has partnered with e-peas, an industry-leading provider of Power Management Integrated Circuits (PMICs), to co-develop a cutting-edge energy harvesting shield kit for the new power-optimized xG22E Explorer Kit. 

This kit includes three dedicated shields that fit snuggly onto the Explorer Kit board, which is optimized to isolate power leakages and facilitate external measurements. The first shield allows experimentation with alternative battery chemistries and supercapacitors. The second shield is dedicated to kinetic/pulse harvesting applications and uses the e-peas AEM00300. These shields provide multiple test points for debugging and power consumption measurement. The third shield incorporates e-peas’ latest and most advanced PMIC, the AEM13920, enabling developers to experiment with dual energy harvesting sources simultaneously. 

The kit includes a host of revisited sample applications for Bluetooth and Zigbee Green Power, along with instructions on configuring the PMIC and optimizing code for energy-based decision-making. 

For example, the EFR32xG22E Explorer Kit is an ultra-low-cost, small form factor development and evaluation platform designed for rapid prototyping and concept creation of EFR32xG22E Bluetooth LE IoT applications. The kit features a USB interface, an onboard SEGGER J-Link debugger, a user LED and button, and support for hardware add-on boards via a mikroBus socket and a Qwiic connector. This hardware add-on support allows developers to create and prototype applications using virtually endless combinations of off-the-shelf boards from MIKROE, SparkFun, Adafruit, and Seeed Studios. 

Wireless SoC solutions for low power and high transmission efficiency 

Silicon Labs’ xG22E SoC family includes multiple product lines, such as the EFR32BG22E series, EFR32FG22E series, and EFR32MG22E series. Below are the key features of these products. 

First, the EFR32BG22 Series 2 Bluetooth® Wireless SoC, including the EFR32BG22 and EFR32BG22E Bluetooth Low Energy (LE) wireless SoC solutions, is part of the Wireless Gecko Series 2 platform. These devices are designed with a strong focus on energy efficiency, offering best-in-class ultra-low transmit and receive power. The high-performance, low-power Arm® Cortex®-M33 core delivers industry-leading energy efficiency, extending coin cell battery life up to ten years. While the BG22 enables energy-efficient applications, the BG22E (where "E" stands for Energy Conservation) further enhances battery longevity and supports designs that eliminate batteries altogether. Silicon Labs’ BG22 and BG22E series are the ideal market-leading SoCs for Ambient IoT or energy harvesting devices. Target applications include Bluetooth mesh low-power nodes, smart door locks, personal healthcare and fitness devices. Asset tracking tags, beacons, and indoor navigation also benefit from the SoCs’ versatile Bluetooth Angle of Arrival (AOA) and Angle of Departure (AOD) capabilities, delivering sub-one-meter location accuracy. 

The EFR32FG22 Series 2 Proprietary Wireless 2.4 GHz SoC, including the EFR32FG22 and EFR32FG22E, is also part of the Wireless Gecko Series 2 platform. The FG22 SoC integrates a 38.4 MHz Arm® Cortex®-M33 core with TrustZone and a high-performance radio with a receive sensitivity of -102.3 dBm. While the FG22 enables energy-efficient applications, the FG22E ("E" for Energy Conservation) extends battery life and supports battery-free designs. This SoC combines ultra-low transmit and receive power (8.2 mA TX at +6 dBm, 3.6 mA RX), a 1.2 µA deep-sleep mode, and innovative low-power features like RFSense to deliver industry-leading energy efficiency. It extends the operational life of products with limited battery or energy harvesting options, such as electronic shelf labels and industrial wireless sensor nodes. 

The EFR32MG22 Series 2 Zigbee SoC, including the EFR32MG22 and EFR32MG22E, is another part of the Wireless Gecko Series 2 platform. The MG22 series offers optimized Zigbee SoC solutions, incorporating a high-performance, low-power 76.8 MHz Arm® Cortex®-M33 core with TrustZone. While the MG22 enables energy-efficient applications, the MG22E ("E" for Energy Conservation) enhances battery longevity and supports battery-free designs. The MG22 SoC combines ultra-low transmit and receive power (8.2 mA TX at +6 dBm, 3.9 mA RX), a 1.4 µA deep-sleep mode, and low-power peripherals to deliver an industry-leading, energy-efficient solution for Zigbee protocol applications, including Green Power. IoT applications include smart home sensors, lighting controls, and building and industrial automation. 

Conclusion 

As we move toward a smarter and more connected future, energy harvesting technology is playing a pivotal role. By converting ubiquitous ambient energy - such as light, heat, vibration, and RF - into electricity, we can reduce reliance on traditional power sources, extend device lifespans, minimize battery waste, and achieve true low-carbon sustainability. With the rapid growth of IoT devices, energy harvesting will become a critical foundation for their long-term, stable operation. The energy harvesting SoC solutions introduced by Silicon Labs will serve as indispensable components in building a greener, more efficient, and resilient connected world.