Generating Power One Step At a Time

The Pittsburgh-based startup SolePower is developing an insole that collects kinetic energy as you walk to power your mobile phone

One hour of walk time with a pair of EnSoles, designed by Hahna Alexander (inset), provides 2.5 hours of talk time on a smartphone. SolePower

For a mechanical engineering course at Carnegie Mellon University, Hahna Alexander was tasked with creating a technology that solved a problem for students on campus. She and her classmates came up with a lot of "crazy ideas," she says, before constructing a shoe that used the energy produced by a foot striking the ground to light an LED on it.

The invention fulfilled the assignment. The shoes would make crossing campus at night safer for students, lighting dark paths for those who wear them and signaling their presence to nearby drivers. In fact, she got an "A." But Alexander and one of her co-inventors, Matthew Stanton, had something even more impactful in mind. "We realized that the energy harvesting mechanism could be embedded in a versatile insole, put in any shoe, and power a variety of devices by charging an intermediate battery," says Alexander.

The pair built a prototype, demonstrated it to various groups and got some initial feedback. A couple of months later, they founded SolePower. The Pittsburgh-based startup picked up $60,000 in seed money through a successful Kickstarter campaign in 2013 and is well on its way to getting its "EnSoles" into major outdoor retailers. Alexander shares her story with

Let's start with the problem. What problem are you trying to fix?

It’s very evident that portable electronics like cell phones, wearable technology, cameras and sensors are becoming increasingly useful in everyday life. We have the potential to connect all the devices around us and to interact with people and things in ways that are incredibly interesting and efficient. Unfortunately, advancements in battery technology aren’t increasing anywhere near the same rate as innovations in portable electronics. That means more time spent hovering over wall outlets, carrying extra batteries and consuming electricity. Essentially, a user can’t be completely mobile because our power sources aren’t mobile. We’re solving this problem by capturing an energy source as mobile as the devices it charges.  

So, what exactly is SolePower? Can you give me your elevator pitch?

As mobile devices advance, their thirst for energy grows, making them more limited by finite battery life. EnSoles are a wearable technology that removes these limitations by turning the wearer into their own power source.

One hour of walk time with a pair of EnSoles provides 2.5 hours of talk time on a smartphone. There is no personal power generator on the market that can match both the EnSole's power output potential and low-profile and seamless integration with the user’s natural motion. SolePower does not depended on external conditions. Rain or shine, day or night, every step you take is a step closer to a full battery.

Generating Power One Step At a Time
The power generated is stored in the "PowerPac." SolePower

How does it work exactly?

During every heel strike in a user’s step, the mechanism inside the insole is activated and converts the linear motion to rotational motion. This motion spins a small, electromagnetic generator as fast as possible for as long as possible. The generated power is stored in our external battery pack, the “PowerPac.” We call the combination of the mechanism and the insoles “EnSoles” for “ENergy inSOLE.”

What is your professional background?

My co-founder, Matt, and I are both mechanical engineers. He has worked in the Biomechatronics Lab at Carnegie Mellon University, investigating the effect on human gait when weight is added to a foot. He’s a natural tinkerer and is constantly building things. This love of engineering led him to a government facility for building nuclear submarines before deciding to start SolePower. Matt’s also an avid hiker and tests the product whenever he has a chance to get outside.

My background is in mechanisms related to space technologies. I worked as an intern at NASA and SpaceX, designed an energy harvesting robot for windy off-planets and worked at the Planetary Robotics Lab at CMU. I’ve always loved science fiction, so the opportunity to bring cool wearable technology like an EnSole to life is incredible.

How would you describe your success to date?

We’ve had lots of great traction and attention over the last two years. In the summer of 2013, we launched a Kickstarter campaign that was successfully funded by over 600 backers, 450 of which paid to be the first to receive the finished EnSoles. This year, we’ve been awarded a Popular Science Invention Award, Africa Energy Award for Innovator of the Year and first place in the Rise of the Rest Competition with Steve Case. We also received an invitation to exhibit at the first annual White House Maker Faire. All of this attention has resulted in a product waitlist of 5,300 people and counting from more than 100 different countries.

How do you plan to scale your company? What's next?

We see anyone that uses mobile electronics and walks as a potential user. However, we will initially target the outdoor market, which includes 35 million U.S. hikers, backpackers and campers who venture into areas with no access to electricity. We are focusing on outdoor gear retailers, such as REI, Dunhams, Cabelas, Gander Mountain and Eastern Mountain Sports. This will provide us with the opportunity to establish our product and brand. Eventually, we wish to transition to an everyday consumer electronics product as well as create a low-cost version for those living without access to electricity in developing regions. Our next step is to transition to large scale production and conduct large, 1000-plus-user trials.

Generating Power One Step At a Time
The PowerPac can charge any device that connects to a computer USB port. SolePower

You envision the military using them too.

We talked to different military/government divisions and currently have a contract with one of those groups. Soldiers rely heavily on various devices while in the field, but just like a smartphone, portable military devices are limited by battery life. The consequences of a dead battery are significantly more severe in the field, so soldiers carry up to 20 pounds of backup batteries. The U.S. military is actively trying to find ways to decrease that load. Our technology is among the ones they see as having great potential.

If you could toss out one question to the masses, in hopes of crowdsourcing an answer that would be helpful in growing SolePower, what would that question be? And why?

How far would you walk to never have a dead battery?

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