The Coming of Age of Ambient IoT: Unlocking the Energy Harvesting Opportunity

Ambient Internet of Things (IoT) refers to the opportunity to connect wireless networks of self-powered devices using energy harvested from local input sources. The latest designs for energy harvesting components allow devices to use energy converted from Photovoltaic (PV), Radio Frequency (RF), thermoelectric, or piezoelectric energy sources, which has opened up the possibility of battery-less IoT devices.

In practice, developing reliable harvesting systems has been challenging, marked by a series of engineering hurdles, high component costs and IoT Original Equipment Manufacturers’ (OEMs) strong preference for battery power. Two innovation ecosystems are addressing these historical challenges:

1. The designers of the energy harvesters, including PV modules, Thermoelectric Generators (TEGs), RF transmitters and receivers, and vibration harvesters.
2. The PMIC manufacturers that develop the chipsets that manage and regulate the Direct Current (DC) generated by the energy harvesters.

Designers of energy harvesters have faced challenges in ensuring the reliable conversion of energy where the nature of the power inputs is unpredictable. In environments where the source is only intermittently available, or has varied intensities, it can be difficult to consistently meet the voltage threshold required to power the device at the appropriate intervals. To ensure devices’ fool-proof operation, harvester and Power Management Integrated Circuit (PMIC) manufacturers have focused on designing versatile harvesting components that can convert and manage almost any energy source, with varying intensities, and in a range of conditions.

Harvester manufacturers have focused on conversion efficiency from low-intensity input sources. For PV harvesting, Ambient Photonics, Epishine and Exeger have developed PV cells that can achieve reliable energy conversion from low-light sources to power devices. In thermoelectric harvesting, EnOcean has developed a TEG that can generate energy from temperature gradients as little as 2° Celsius (C). In RF harvesting, where frequency range and interference have been historical challenges, Powercast’s RF-to-DC converter chips can harvest energy from 10 Megahertz (MHz) to 6 Gigahertz (GHz).

Texas Instruments and Analog Devices have a long-standing history of PMIC development, and have chips that can support energy harvesting systems. However, the latest entrants are changing the face of the energy harvesting power management ecosystem, giving rise to “energy-agnostic” systems. For example, e-peas is dedicated to developing PMICs for energy harvesting, and claims that its PMICs can transfer energy to 99% of available storage elements. e-peas’ portfolio covers 99% of the world’s available energy sources, and has dedicated chips for PV, thermal, vibration, pulsed intermittent, and RF harvesting.

PMIC vendors have also been focusing on developing power management units that can support dual-source harvesting in environments where there are two or more available inputs. For example, Trameto offer OEMs customizable PMIC designs depending on the ambient environmental conditions of the device, and can select two or more energy sources to manage. In cases where there are two lower intensity energy sources, having a fallback power source is particularly valuable in ensuring reliable operation.

Enhancements in harvester and PMIC design are addressing many of the factors that have previously stifled the ambient IoT opportunity, but challenges remain in driving market awareness.

For PMIC and harvester vendors, the availability of cheap battery power in running low-power IoT devices is a major obstacle. The upfront cost of disposable batteries is a considerably cheaper alternative to more complex energy harvesting components. However, harvesting companies claim that implementers of ambient IoT device systems will create Operational Expenditure (OPEX) savings by reducing the maintenance costs of identifying and replacing batteries in the network of devices—but these need to be quantified.

To enable this, PMIC and harvester designers need to collaborate with OEMs to co-develop Proofs of Concept (PoCs) that demonstrate the opportunity for costs savings over product lifecycles. This is particularly needed in industrial and asset tracking IoT markets, where the energy harvesting opportunity has yet to get off the ground.

IoT OEMs should collaborate with harvesting companies to establish the most appropriate component bundles to optimize device performance according to the available ambient power sources. With EU restrictions on non-rechargeable batteries taking effect in 2027, developing harvesting systems is likely to be a sound strategic investment, with implementers’ own Environmental, Social, and Governance (ESG) targets in mind as well.