Finding Alternate Energy Sources for IoT Devices
All Internet of Things devices require power to track the assets in which they are installed. But a major challenge in deploying wireless sensor networks is the limited length of time during which the sensors can do their jobs.
Using batteries in sensors brings major drawbacks. First, there’s only a finite amount of energy available in the typical battery.
In addition, the cost of replacing batteries in thousands of devices, especially those in out-of-the-way or hazardous locations, can make deploying wireless sensors inconvenient and cost prohibitive, according to Ahmad Salman, assistant professor, School of Integrated Sciences at James Madison University and an IoT device expert.
“When you’re trying to deploy wireless sensor networks that would track certain birds in the jungle, you expect to deploy these and leave them for five years to gather as much data as you can from that span. You’re certainly not going to go and charge the batteries or [replace them] every once in a while,” he said.
The answer is to charge these batteries by enabling sensors to harvest energy from the surrounding environment, said Jerry Luo, a lecturer in energy storage and energy harvesting at Cranfield University in the United Kingdom.
“That [energy harvesting] means we don’t need to send someone to replace the battery or charge the battery because the sensors will be able to operate by themselves and for a period of time that is long enough to collect the data,” he said.
The process of collecting energy from outside sources—such as light, heat and vibrations—is to power IoT devices is called energy harvesting.
These sources power IoT devices differently. Let’s look at these methods in turn.
In many cases, solar energy is the No. 1 option unless the sensor is underground or in a location without sunlight, Luo said.
A rechargeable battery combined with a solar panel is sufficient enough to power an IoT device indefinitely, said Shams Kanji, manager of technical sales engineering at the Morey Corp.
In these applications, the IoT device is configured to read the sensors and typically transmit data every two to four hours, he said. The device configuration is smart enough to scale the data reporting based on the stored power.
In most outdoor locations, the rechargeable batteries can store enough energy when there is sunlight to keep things running when darkness falls and in bad weather.
“Solar panels and rechargeable batteries work for most environments and geographical regions but not all, for example: Alaska in the winter months,” Kanji said.
Mechancial energy is another energy source to power IoT.
“Machinery that can be deployed in power plants produce their own vibrations, and the vibrations from that heavy machinery produce a lot of energy,” Salman said . “These can produce up to 150 microwatts per centimeter square that can be used. So, if you have IoT devices that are on manufacturing belts or something like that, you can power these completely from the vibrations that are being produced by the machine that they’re monitoring.”