Whenever I talk about our work in Energy Harvesting, I'm usually met with the same confusion. People often associate energy harvesting with alternate energy, and while there are similarities, the two have very different goals. First, alternate energy is the term used for large scale production of energy from renewable sources, such as wind farms and solar panels. The goal of alternate energy is grid offset, or reducing the use and dependence on fossil fuels.
Energy Harvesting is similar in that it is the collection of wasted or unused energy, but the goal is much different. Energy Harvesting does not collect anywhere near the amount of power that would be required for grid offset. Alternate Energy sources typically create energy in the Mega Watts (MW) whereas Energy Harvesting is gathering energy in the Micro Watts (µW) to Milli Watts (mW). For reference 1 MW is equal to 1e+12 µW, so it's easy to see that grid offset is not a realistic option for energy harvesting.
So what is the point?
While micro watts and milli watts might be far from powering your home there are lots of small electronic devices that can be powered from that amount of power. The IoT, or Internet of Things, is an emerging market that is creating more and more value for the power available from energy harvesters. The IoT is best understood from a perspective of our current internet environment. Currently, we live in the Internet of People, that is people connecting to information, other people, and other inanimate things. Conversely, the Internet of Things, is the idea of inanimate objects (things) that are connect online to other things, and to systems that all require no human interaction. So, what's the point? Well for one, think of a swarm of drones, they must all communicate to one another without human intervention in order to create intricate flight patterns and avoid crashing into one another. In a more practical sense, imagine a manufacturing facility that is completely connected at every point and instantly knows when a machine involved in the process is overheating or off time and the system is able to adjust adequately to correct the issue without human intervention. This would create a highly efficient system that would reduce downtime, waste, and increase production.
So how does the IoT work? Every IoT solution will have different elements and different needs but there is a general framework that they all fall into to some degree. Every IoT solution involves several aspects:
Sensors - for data collection
Nodes - for data aggregation
Gateway -transfers the data to a cloud or fog network for processing
Result - actionable information or actuation
Sensors are always there first layer, also referred to as the edge. Over the past few decades the power demand for sensors has been continually dropping. However, with the consideration of thousands of connected sensors within a single facility that are all communicating together, a few issues arose. Primarily a need for increased security features, onboard data transmission, and a cpu for initial data processing to speed up the overall system. All of these added components have increased the power demand for sensor that would exist as the first layer of an IoT solution.
And that is where Energy Harvesting comes in. For similar systems the cost of installation can account for 30 - 40% of the overall cost. That makes many of these systems cost prohibitive for smaller facilities. Additionally, battery power is also cost prohibitive in many cases. While the upfront cost of batteries is very approachable, the ongoing cost of battery replacement - including downtime, man hours, and parts - can accumulate rapidly over only a few years. So, conversely energy harvesting offers a one time installation that is both low cost upfront, and does not require the ongoing cost of battery replacement.
While energy harvesting may not be enough power for every situation, there are many different methods that are available. When designing your IoT based solution, be sure to investigate your energy harvesting options first to see if there is a power generating option that is right for you.