Here's why energy-harvesting trumps batteries

Smart devices surround us. Today, we have an unbelievable array of smart-products that perform an incredibly diverse range of tasks. Moreover, outside the consumer-facing IoT market, there is the huge Industrial Internet of Things (IIoT) market, which is set to grow exponentially in the near future. Sensors are being deployed in large numbers, in many (even,traditional) industries, to harness the power of data. We have billions of connected devices already - The Internet of Things (IoT) is no longer a concept - it is well and truly here. According to American research firm, Gartner Inc, there will be a whopping 20.4 billion connected things, in active use by 2020. In the long run, batteries just won’t be able to keep up with the demand for Internet of Things (IoT) devices.

However, powering IoT devices poses a bit of a tricky problem. Using batteries to power IoT devices is really inefficient and uneconomical. Batteries present a whole host of complications which makes them poorly-suited for IoT devices, especially sensors in remote locations. There is increasing consensus among experts that IoT devices need to be self-powered, in order to be viable at scale.

“In many cases, the cost of accessing a remote sensor is much higher than the cost of the battery itself.” 

IIoT and the power problem

The internet of things (IoT) is a network of interconnected devices, i.e sensors, microprocessors and MCUs etc. In consumer IoT devices such as smart appliances and wearables, this is not a major problem. They usually come with rechargeable batteries and more importantly, consumer IoT devices just don’t come in large enough numbers for this to be a real problem. 

On the other hand, in an industrial IoT (IIoT) setting, the problem is much more severe. Industrial operations use vast numbers of sensors that are required to be constantly operational, often in unfavourable environmental conditions. Battery maintenance and replacement are significant challenges against increased adoption of the industrial IoT.

What’s the problem with using batteries to power IoT devices?

IIoT devices include remote sensors that are deployed in a variety of sites, to gather highly specific data. There are billions of IoT devices that are currently being deployed to gather data for industrial purposes. Often, these sensors are placed in very remote locations that can be quite inaccessible - for instance, you could have a weather sensor placed on a mountaintop or a humidity sensor on the roof of a warehouse; We might even have a medical IoT device that’s deployed inside your body. In these cases, it can be very difficult (or even impossible) to access these edge devices and replace their batteries. With the number of IoT sensors being used growing exponentially, having them run on batteries would mean a logistical nightmare. After all, the whole idea behind the Industrial Internet of Things (IIoT) is to improve efficiency and streamline industrial processes. And so, having to replace batteries on these devices essentially defeats their purpose. Moreover, even if these batteries have long battery lives, battery replacement will spell increased costs, which will be another barrier in the way of cost-effective Industrial IoT. In many cases, the cost of accessing a remote sensor might outstrip the cost of the battery itself.

Moreover, some of these sensors are extremely tiny and therefore, can’t accommodate a large enough battery to meet the power requirements. This can be an especially pertinent problem for medical IoT devices. As such, medical implants have to contend with a number of crippling constraints. One of the key constraints with medical implants is size. This is all the more reason why an ultra low-power, batteryless sensor might easily represent a more elegant solution than a battery-powered sensor. 

Here are a few of the issues with using batteries:

1. They have limited lifespans
   This one is rather obvious - batteries come with finite lifespans. This could result in there being gaps in the transmission of mission-critical data. Concerns about battery life also results in manufacturers often configuring their sensors to transmit data less frequently, in order to reduce power consumption. These devices sacrifice density of data and the insights that could offer for a longer battery life. This isn’t going to be sustainable in the long run.
    
2. There is not enough lithium in the world
   Batteries use Lithium. It is an incredibly rare substance - If we were to use Lithium to make 10 trillion sensor batteries, it would require 10 years’ worth of the planet’s total Lithium output. There is just not enough Lithium in the world to power all IoT devices using batteries. Mining Lithium is extremely detrimental to the environment, having been shown to cause water shortage and air pollution.
    
3. Maintenance costs
   Over the lifetime of an organisation, batteries will spell significant costs for the company, in the form of maintenance. They require a low-battery alert system to be installed or a system of changing all batteries at a preset time, both of which add up to a higher cost of ownership.
   
   Replacing batteries on mobile sensors could be extremely difficult and expensive. In a facility with thousands of sensors, it would be very difficult and prohibitively costly to locate sensors and replace their batteries. Some batteries can be so challenging to replace that they would require a specially trained technician to be hired. 
    
4. Environmental impact
   As things stand, safely disposing batteries is proving to be a massive challenge. Batteries often contain many toxic substances such as Lead, Cadmium, Nickel and Mercury, which are extremely detrimental to the environment. Recycling these substances can be very expensive.
   
   Using batteries to power the IoT devices of the near future could well have catastrophic consequences on the health of our environment. Battery-less sensors powered by technologies like energy harvesting, in addition to being more practical, are also the more eco-friendly option.

The numbers just don’t add up

Here’s an example to help you truly appreciate the nature of the problem. Imagine you run an industrial operation and you have 10,000 wireless nodes installed in your facility. Let’s say these sensors have been installed to transmit vital information about the working of your equipment. 10,000 sensors mean 10,000 batteries. A realistic average battery-life of 3 years would translate to replacing 3,333 batteries a year, or about 9 batteries a day! And replacing batteries in some hard-to-reach locations could easily set you back a few hundred dollars. Moreover, even accounting for a measly 15 minutes to change 1 battery, you are looking at 821 extra hours of work per year. 

At scale, these numbers quickly add up to astronomical amounts. Over the lifetime of a commercial operation, they significantly add to the Total Cost of Ownership (TCO); The high cumulative cost of maintenance, disposal and replacement makes using batteries highly untenable, at scale. If we assume the same 15 minute change time and apply it to a trillion sensor world, we would need the efforts of 28,538,813 human beings, full time!

These outrageous numbers only serve to show just how untenable an idea it is to use batteries to power IoT devices.

Ok, So how do we get around these problems?

One way to circumvent these problems is to get rid of the battery altogether. Thanks to advancements in semiconductor technology, we now have self-powered sensors that operate using extremely small amounts of harvested ambient energy. These sensors don’t need a battery and often harness energy from their surroundings. There are many types of energy harvesting - eg. RF energy harvesting, Piezoelectric energy harvesting etc.

Ultra-low-power sensor devices, powered by ambient energy, are poised to change the world of IoT forever. Self-powered IoT devices don’t need to compromise on accuracy or frequency in order to make up for a long battery life.

Why self-powered sensors are the future

Self-powered sensors are maintenance-free and have zero cost of operation. They promise an elegant solution to the power crisis that has withheld more rampant adoption of the IIoT. Battery-less sensors are definitely the future of IoT devices. 

We’ve already established the massive financial incentives that self-powered sensors provide to industries, however, much more importantly, they represent a much more ecologically sustainable option. It is our ecological responsibility to ensure that the Internet of Things (IoT) is a self-sustaining entity in terms of power consumption. 

ONiO.zero is a self-powered, battery-less microcontroller that offers a unique solution for any IoT device by eliminating the need for batteries. No batteries, no maintenance, lower BOM cost, and smaller designs. Read more about ONiO.zero here.