Harnessing Ambient Energy with Adidas

Joel Olympio
7 min readDec 25, 2022

As I walk in the bitter cold to the gym, my headphones sip on the severely low solar energy being emitted by the Irish sun. They play a cacophony of electronic melodies and tones, expending an electrical to sound energy transformation. Synonymously, photoelectric weaves in the head band breathe in natural photons to power this energy transformation in a seamless and effortless cycle.

Harnessing Ambient Energy with Adidas

I haven’t thought about charging these headphones in weeks.

I bought the Adidas RPT-02 SOL headphones about two months ago now and I have manually charged them with a cable only once. The first time they were charged, was shortly after I received them. I charged them to full capacity and since then, they have never been electrically charged through cable. My regular short 25-minute walk to and from the gym, as well as charging from indoor gym lighting and bedroom lighting has sufficiently kept these headphones powered for precisely 6 weeks now and counting.

The Adidas RPT-02 SOL are perfect gym headphones for me.

It is amazing to pick up an electronic device and know it has enough power for use, to not even have to check its battery percentage, to pick them up, turn them on and know they will not give you a battery warning halfway through your workout. The Adidas RPT-02 SOL headphones have the sense of an analogue product despite their technicality. They feel like some object that is just magically able to work without the restraint of a battery.

Context Matters

What makes the experience of the Adidas RPT-02 SOL headphones magical is when you use them for the context they were designed for. These are not your everyday headphones, nor your office headphones, gaming headphones or just casual entertainment headphones. These headphones are designed to the core for an active lifestyle. To use them for any other context really diminishes their functionality and here is why:

The design of these headphones, from the material selection, part washability and rigidity, physical interaction and even sound calibration are designed for exercise. I can imagine the user personas Adidas and Zound Industries had pinned up left right and centre when designing these headphones and they were completely right to go in this direction. The technology used in the headphones is provided by Exeger who have created PowerFoyle, an innovative thin material technology that can harness both outdoor and indoor light to power devices. Yes, the Adidas headphones can be charged indoors, and I use to leave them lying out under a light or lamp when not using them, but indoor lighting is much weaker than outdoor lighting. To rely on it alone to charge these headphones sufficiently would not be much of a muchness in terms of efficiency. The power used by the headphones when playing music or even when just idle is usually more than that provided by indoor lighting. Therefore, primarily outdoor lighting is where these headphones shine in efficient charging; the power input from the sun is greater than the power output from headphone usage. Even just short walks under a Winter sun, with dense cloud coverage and often rain, was enough to keep these headphones sufficiently charged for weeks but placing them under an artificial light even overnight both defeats their purpose and is not as effective in charging the headphones.

The Adidas RPT-02 SOL has an associated app that shows you charging information. This screenshot was taken when I was using the headphones outside. As you can see the solar energy being provided (this was a cloudy day in October) was more than the energy being used so as I was using the headphones they were actually gaining energy!

The headphones should harness ambient energy and ideally you shouldn’t think too much about if they are charged, they should always be charging by availing of whatever light is available to them in the environment they’re in. The only thing you might want to think about is where you leave them when not in use. For the first week or so I often left it by a window so it would charge during the day. But after a while I stopped doing this and often just threw them on top of my gym bag or even left them inside it. And still, despite this, both a combination of my short “cardio” walks to and from the gym as well as the indoor lighting at the gym kept these headphones charged for an exceptionally long time in comparison to my Surface Headphones 2 which need charging every 2 or 3 days.

Adidas RPT-02 SOL headphones on a Christmas tree

As I write this the Adidas RPT-02 SOL headphones have 18% battery, 6 weeks after their first and hopefully last full charge. I would like to add that my active lifestyle doesn’t even include much outdoor activity, yet these headphones have still been incredibly power efficient. I think it’s also worth pointing out that the headphones are often only used for about two hours, 4–5 days a week which again comes back to use case. Short term daily use of these headphones can be more ideal in terms of power longevity, though if you use them for longer term outdoors this wouldn’t be a problem (except for comfort, they are on-ear headphones).

Surface Headphones 2 and Adidas RPT-02 SOL

My Surface Headphones are often used for 3–5 hours a day, almost every day, where I often switch from active noise-cancelling to ambient sound amplification and back — they have a different use case and hence are more power demanding. I guess where I am going with this is these headphones are perfect if your niche lifestyle suits their niche feature. And it’s not that they fall short when applied to typical headphone/earphone usage, they have enough battery to keep up with and even surpass other headphones, but their core feature, ambient light charging, becomes less useful and relevant when not used in an active or commuting lifestyle. And when that core feature becomes well… less core to the use case, then they’re just another pair of headphones, costly headphones, competing against tough competition.

An Urban Competitor

A direct competitor to the Adidas headphones are the Urbanista Los Angeles which offer the same PowerFoyle solar charging technology but in a more minimal form factor. Urbanista likely had quite different user personas pinned up when designing these and it shows. They seem designed for a wider audience that’s not so niche. They may be tailored more towards the commuting, general outdoor activity life than the more specific exercise active lifestyle. Anyone could wear these minimal headphones and onlookers wouldn’t even realise these headphones are harvesting photons (or light waves!) and turning them into sound waves.

Urbanista Los Angeles

Furthermore, they feature an over-ear design so they would definitely be more comfortable than the Adidas RPT-02 SOL (they also have a less robotic name). On top of all that, they’re €30 cheaper. But despite all of that, I would oddly enough still buy the Adidas headphones over the Urbanista Los Angeles, not for any reason other than they suit my use case more. I enjoy the rigid design of the Adidas headphones, I like being able to throw them around, shove them into a bag with no case and know they’ll be all right. I appreciate that I can take the headrest piece and earmuff covers off and wash them if necessary. I prefer the physical nub interface that I can use to switch songs and control volume as I find capacitive touch interfaces on headphones gimmicky, unintuitive, and not nice to use in the cold. And honestly, I’m drawn to their funky exercise aesthetic, it adds to their purpose in my life, exercise headphones, and I like when products have a defined purpose for a defined environment.

The Future of PowerFoyle

Exeger’s PowerFoyle technology has exciting potential for other applications. There are many products with low powered functionality and interfaces that are either often used outdoors or lay idle indoors that could benefit from the technology. The future of wearables in particular is one area where it may have significance. The key to successful application however, as I hope I’ve indicated in this article, is use case. PowerFoyle would not be useful on an Xbox controller but could be useful on a pair of smart glasses. PowerFoyle would not be useful on a car but could be useful on a dash cam. One must also weigh the pros and cons of using PowerFoyle over a more efficient battery and the cost of adding the technology which does seem to significantly increase the sale price of a product when compared to their non-solar charging counterparts. Would PowerFoyle really truly compliment the product’s use case and use case environment, or would it just be a greenwashed cash grab gimmick?

Exeger Powerfoyle is a very exciting and adaptable technology.

I’m fascinated and intrigued by the idea of harnessing ambient energy on a more individual level. I feel it brings us closer to replicating nature’s wasteless energy cycle where everything from the sun down to a dying cell is factored into an ecosystem of efficient and non-polluting energy circulation. I don’t think we will ever reach that natural level of circular energy efficiency, but I think it can inspire how we think about our energy consumptive and transactive tendencies.