Always-On Energy Challenges

What’s the real cost of connecting everything?


The roar over the Internet of Things these days is almost deafening. Inside of China, everything being made for the domestic market is smart-ready. And companies ranging from watchmakers to appliances to automotive manufacturers are building connectivity into everything.

The problem is that in order for it to work as planned—to communicate with other devices and send alerts to consumers or repair people—at least some portion of the device has to be on all the time. These are typically very low amounts of energy, sometimes measured in microwatts, and frequently they consume less energy than leakage current at 40nm with a processor that’s supposedly turned off.

But collectively these devices add up to a significant of energy, and energy costs money. A recent report by the National Resources Defense Council, put the annual price tag at $19 billion in the United States alone, which is roughly the output of 50 large power plants. In real dollars, this equates to between $165 and $440 per household, depending on utility rates.

So what can be done about this? From a design perspective, there are a number of steps that can be taken, many of them for devices connected to a plug. The NRDC has been very vocal about set-top boxes that are always on and drawing power, and to a large extent the most recent report is an extension of that. But it also points to a huge opportunity for companies developing chips for white goods, security systems, set-top boxes, and automotive ECUs. The same kind of awareness about power that has been drummed into the mobile electronics market needs to be applied elsewhere, and consumer awareness has been raised to the point where people may be willing to pay for it.

Still, there’s more to this picture than meets the eye. Two devices that are always on may draw very different amounts of energy, and there are some factors that haven’t been widely discussed:

  1. Security. Connected devices require some level of active security if they are always on. Depending upon how many connections are available and the system’s architecture, that could be a very small amount of energy or quite a lot. Given the very public breaches that have occurred and fear over hacking personal accounts, people may be willing to spend extra to guarantee that kind of security, which will only increase the total energy consumption.
  2. Wireless access. As many people already recognize, battery life on a smart phone is significantly lower in areas where there is bad reception than right next to a cell tower. It’s no different for home appliances, which will constantly attempt to make a connection and take longer to transfer data where signals are weak or bandwidth is lower.
  3. System longevity. Always on features may draw very little current, but there is no data at this point as to what that will do to the lifespan of parts and systems. Much of this involves thermal effects and electromigration, but as parts go bad what happens to energy consumption? And what happens to total cost of ownership?

We are just at the beginning of mapping out the real costs of the IoT and always-on devices. But as devices get connected, so do costs—of energy, architectures and use models. As a result, the real costs may be significantly higher than what appears in the NRDC report.

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