Keeping The Lights On

Going beyond Li-ion batteries to power the IoT


IoT is comprised of numerous industries. For the sake of analysis, these can be segmented into several tiers that function as independent networks or integrated complicated meshes. In my November post I examined the three-tier IoT architecture at a high level. Then last month I focused on the rapidly expanding market of intelligent gateways.

Gateways receive information from cloud applications, other gateways, and the trillions of edge devices such as sensors and actuators. Out of necessity, many gateways will be in close proximity to the edge devices, which themselves will be very distributed. And many of the applications relying on these devices simply will not have wired power at the edge or the gateway location.

The clear implication is that power is another market where winners will be produced by IoT.

Batteries today are the most often used and considered as the only power alternative for remote gateways and devices, one reason why most battery forecasts remain robust. Elon Musk’s mega factory for lithium-ion batteries may have monopolized media attention over the last year, but an emerging class of post-lithium batteries is shaping up to be a huge market in its own right. These technologies — including silicon anode batteries, lithium sulphur batteries, sodium ion batteries, magnesium batteries, lithium air batteries, solid state batteries and lithium capacitors — will comprise a $14 billion market within a decade, according to one estimate.

Energy harvesting
All batteries need to be charged, which is where a host of other opportunities will emerge as IoT expands. Solar is at the top of this list.

Mention solar to a colleague and you’re likely to hear an anecdote about relative large scale deployments, such as panels on roofs of homes and factories or sprawling solar farms in the desert. However, there are countless examples of small scale solar coinciding with the rise of IoT. Here are a few:

• Jeff Kettle, a Bangor University researcher, is working on organic photovoltaics (OPVs) that are flexible enough to be molded into clothing, and so cost effective that they earn back the energy required to manufacture them in just one day. In comparison, this so-called energy payback time for silicon solar cells is one to two years.
• Fujitsu has developed this small solar-powered IoT beacon, meant to replace IoT tags that currently use small batteries.
• Two MIT engineers made news last summer for developing a small ultralow-power circuit with vastly improved efficiency in converting solar energy into electricity.

Solar/photovoltaic devices accounted for more than half of the 41.2 million global energy harvesting units forecast to be shipped in 2015, according to an IDTechEx report last fall. Other power harvesting technologies include piezoelectric and electrodynamic and thermoelectric (harvesting energy from heat). These technologies will be deployed in market segments as diverse as those represented by IoT, such as automotive, transportation, industrial, mining agriculture to name a few starting to adopt these more unique solutions, where energy in the form of vibration and thermal gradients will power a range of sensor and actuators.

Back in 2012, Yole Développement released a report stating that the first “real” energy harvesting market would be wireless sensor networks in new and remodeled commercial buildings. The report predicted the overall market would reach $250M by 2017, almost certainly an underestimate.

While methodologies can vary across analyst firms, it’s noteworthy that last fall’s IDTechEx report forecasted the global energy harvesting component market to be $1.25B in 2015, growing to $3.29B by 2020. IDTechEx expects unit shipments to grow at a compound annual growth rate (CAGR) of 26% over the same period.

The stage seems set how to keep the lights on, metaphorically or otherwise, in the Internet of Things. A stable supply of power will be provided by batteries, many of which will charged by free energy sources near (vibration as people walk across the floor of an office building) and far (the sun). However, one drawback worth examining is that eventually all batteries need replacing as they lose the ability to accept a charge over time.

Thus another opportunity for new winners — supercapacitors.

Near limitless charging
The key trend is that energy density of supercapacitors is on the rise and may soon approach that of batteries. Historically, supercapacitors have compared unfavorably to batteries in many applications due to cost and the important energy storage-to-weight metric.

Supercapacitors already have displaced lithium ion batteries in many Chinese buses. And supercapacitors compare favorably in one of the most important criteria of the remotely located and widely distributed segments of IoT — they never lose their ability to be charged. So look for applications, especially those that require instant high energy, to favor supercapacitors.

IDTechEx forecasts a 10-year, 30% CAGR for the supercapacitor market, which the firm says will reach $6 billion in by 2024. Here it’s essential to point out the mistake in framing this as an either-or proposition given advances in hybrid supercapacitors or “supercabatteries,” which combine the best of batteries and superconductors.

Surely the demand for all sorts of harvesting and storage technologies will be huge. Consider: 1 trillion sensors will use 21,900 Gigawatt hours (GWh) per year, about the output of a few nuclear power plants. That’s according to Kettle, the Bangor University researcher mentioned above, who notes that his estimate doesn’t include the extra power data centers will need needed to store and analyze all the edge-generated data.

The near-term IoT power market will be $20B to $40B. A market this large will definitely produce winners, including energy device suppliers, new design automation applications, and embedded software for energy and thermal management.

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