I recently sat down with Yogesh Ramadass, a design engineer with Texas Instruments. He’s as much of an expert on the subject of energy harvesting as anyone I know, so I asked him some pertinent questions on the subject.
What’s the real definition of energy harvesting?
In the broadest sense, any situation where one uses freely available energy from the ambient to get useful work done should be classified as energy harvesting. That raises the question, doesn’t most of the useful energy on earth come from the sun? And the answer would be yes, the earth is one big energy harvester, harvesting the available heat and light energy from the sun. Plants and animals on the earth harvest the sun’s energy for everyday living.
For a more specific definition of energy harvesting as it applies to electronics, energy harvesting refers to the conversion of ambient energy available in the form of heat, light, wind, and mechanical energy into useful electrical energy to power electrical and electronic items. This ranges from the megawatts of power harvested using big wind, tidal, and solar farms to the relatively tiny microwatts and milliwatts of power harvested by small solar cells, thermal harvesters on vents, and vibration harvesters on machines.
What can we do today with energy harvesting, specifically in the very low power space?
Today, we have energy harvesting systems that can reliably harvest from tens of microwatts to a few milliwatts of power, depending on the ambient surroundings. For example, small solar-cell-powered systems in indoor surroundings can typically harvest a few tens of microwatts. Taken outdoors, that same system can increase its power capability to a few milliwatts. With this amount of power, we can run small temperature, humidity, and chemical sensors, which can relay vital information to a central hub. With the ability to be self-powered, the shackles of a fixed energy source like a battery can be removed, paving the way for widespread adoption.
What can we expect energy harvesting to look like in the next five years?
In the next five years, the energy harvester and the storage technologies required in these systems will be more mature. The electronics within these systems will also be pushing new lower power regimes, making it more viable to use energy harvesting to replace batteries, both from technology and cost perspectives. When this happens, we will see harvesting devices all around us, in home-automation devices, wearable devices monitoring our health, industrial sensors, and many others.
It's nice to get some perspective from an expert, especially when there is so much research and information about energy harvesting out there at the moment. It's good to know he thinks that the invention of new energy-harvesting devices is on the rise and that their use will mature in the next few years. This seems to be the way research and the market is trending as well.
In a relevant scenario, thinking on a large scale level, i hope in the future the prices of these renewable energy utilities reach a certain manageable level. Being a design engineer in this field myself, i know how hard it is to design a cost effective solution for the users. The off-grid systems are especially very expensive due to the additional use of batteries. Mostly in commercial areas people are leaning towards on-grid solar systems, because the off-grid system is not viable. Though the firms are saving large amounts of money using the on-grid systems as well, but we are still dependent on the grid. But seeing the rapid developments in this field, i am hopeful that this dependence will be one day completely eliminated.
The ability to get rid of batteries for low power devices, many of which may be in places difficult to access, is a major driver of this technology. As storage gets better, as well as on demand production, we will see many devices converted. I can just see using this for the computer on my bicycle. I still haven't gotten around to replacing that battery.
I know exactly what you mean, Lou! I had these great noise-cancelling Bose headphones that were a present from a friend but the battery died and I could not for the life of me even find it, yet figure out how to go about replacing it. So the headphones are somewhere in teh bottom of a box in my storage room. Energy-harvesting will help change scenarios liek this I hope!
I agree Lou. The energy can be harvested using whatever method you like, but the real challenge comes in the storage. Due to the high fluctuations in this type of power generation, a storage device is still mandatory. Capacitors and Super Capacitors can be used for some low power applications, but when it comes to prolong power distribution, we still need batteries. The batteries are still the real bottleneck of our energy sector even when using alternative methods of power generation.
Yes, Daniyal, I think you are right that storage will turn out to be the deal breaker when it comes to using energy-harvesting on a grand scale, but it's still going to be a great option for low-power and ultra-low-power devices, especially very small ones where batteries just aren't practical. But I think combo energy harvesting/storage devices will become more prevalent in the future, so you won't have traditional batteries per se, except in the sense that they are self-sustaining and perpetuating batteries due to the harvesting. Not sure if this would work on a grand scale, though.
Excellent post Rich. I think the real "take away" here is our continued ability and willingness to drive this technology. I certainly feel it's the proper way to go. Any time we can reduce our dependence upon fossil fuels and obtain available alternate sources of energy we are money ahead. I am always amazed at the idea coming forth relative to this subject. The one that blows my mind involves "collecting" energy from pressure derived by footsteps. Great use of otherwise wasted energy. Again-excellent post.
Thanks Richard for such an informative post , No dount this method is making very famous these days and not only through solar we aare harvesting enegy but engineers gave developed many different ways as well. In England tiles are adjusted on the foot path to harvest energy when people step on it .
I have read somewhere that in some club of America tha dance floor has the mechanism of harvesting energy as the people places preasure on the floor while dancing . We can say that this technology is on its boom and definitely in future it will be very usefull.
Debera, your comment is interesting to me. When you say "England," do you mean in London? I actually have written about floor-tile technology that was used during the Olympics in London, and wondered if this is what you were referencing or if there is other energy-harvesting technology being used on footpaths.
Here is a story I wrote for your reference: http://www.designnews.com/author.asp?section_id=1386&doc_id=262295
I am just curious if there is another company or some other technology being used of which I am not aware. Thanks!
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