David Carroll   Wake Forest University Wake Forest University

David Carroll is a nanotechnologist working on a simple material that he thinks will soon be a part of everything you own.  

Carroll's research group at Wake Forest University developed a flexible fabric that makes electricity from heat or movement. It could revolutionize cheap, renewable energy.

Thermoelectrics are not exactly new, but usually made of materials that are brittle, heavy, and expensive. 

Carroll's fabric, on the other hand, is lightweight, feels like wool felt, and can be wrapped around surfaces or even sewn into clothing.  

While energy can't be "created" this fabric can essentially pull electricity out of thin air, from heat and movement.

The fabric Carroll's group has can turn heat — from your body, the sun, anywhere — into usable electricity.  

And unlike anything ever before, it can simultaneously collect power from vibrations or movement — letting your smartphone case bounce on a carseat during a long drive could charge your phone.  So could a shirt flapping in the wind. 

Listening to Carroll, you get the sense that this power felt is going to be everywhere. It can be wrapped around your house, and every appliance inside it. Before you know it eager smartphone users will be fighting over heating grates instead of outlets.  

We talked to Carroll about the fabric that soon may be stitched into every shirt, lying under every car hood and wrapped around every house.

Business Insider: Can you explain how this works?

David Carroll: Thermoelectrics work like this: If you grab a bar of metal at one end, the metal under your hand begins to heat up and that makes the electrons there move faster.  And some of those move down to the other end where the temperature's cooler and so now you have more electrons at one side of the bar than the other. And that gives you a voltage and that voltage can be used to drive things.  

So in order to get really good thermoelectrics, we use exotic materials that can move lots and lots of electrons very, very fast, but that don't allow the transfer of heat. These are ceramics.  They're very expensive and they're very exotic. They work very well, but they're just not very useful in the sense that you can't apply them in many of the places where heat sources exist.

For instance, these hard ceramic modules will not do very well in trying to pick up the heat from my body, even though my body produces 100 or 120 watts of energy, or heat power at any given time.

BI: Where did this idea come from?

DC: Well, originally the idea came from my ten-year-old daughter.

The whole idea was to take isolated heat sources, like a human body or a car or a home sitting in its neighborhood and wrap it in something that would be able to capture the heat better. And so you can't really do that with most thermolectric material — they're not flexible, they're not fabrics. So my daughter, she's very clever and we were talking about this, she said well it would be cool if you could make it flexible. She had the idea of putting it on the back of a phone. She wanted to charge a cellphone with it. 

Cory Hewitt Working with Power FeltKen Bennett / Wake Forest University.

BI: You could use body heat to charge a phone?

DC: From a body that is producing 100 to 120 watts of power, you might be able to get one or two watts of power out of that. If you make clothing out of that, that's enough to start running electronics, like cellphones and things of that nature. And we've actually built some of those. We have put our power felt onto T-Shirts, we've put [it on] connectors for the iPod and things like that.

And so it's pretty nice. It's not totally efficient, but it's not meant to be. It's just meant to supplement the battery.

BI: How much does this cost?

DC: It's very, very inexpensive to make. For something on the order of a quarter, you can use it to cover your laptop computer.

Now the biggest complaint we all have about laptop computers is that the batteries don't last, right? I can't fly from North Carolina to London and work on my computer.

So what if you could extend your battery 30 percent and it only cost you a quarter to do it? See that would make a lot of sense. It's practically free, and the only thing I am doing is giving you a different style of cover than you would normally use.

You could also embed it in your [smartphone] case.  You're maybe adding another dollar to the cost of the case.   

Or if you have a home like my house here in North Carolina — it's been cool here for the last few days — if you look, the home is leaking about a kilowatt or so of power out into the environment. Well I could capture a whole lot of that and run my refrigerator with it.

We already wrap houses in Tyvek [a product from DuPont that insulates houses and reduces heat loss and manages moisture]. So if you could wrap it in something that could do what Tyvek does, but it also produced power — say as much power as the solar cell on top of the roof, then why wouldn't you do it?

BI:  And this is just a fabric we're talking about, right? This can be used in clothing?

DC: You can use it in all of the different places you use fabric. It feels like it, it behaves like it, you can even wash it — haha — we know that by accident.

I had some samples in my pocket and my wife ran it through the washer and dryer. It actually washes just fine.

BI: How efficient is it?

DC: You can collect somewhere in the neighborhood of one milliwatt or so per square centimeter of the covering.

Power Felt Charging on MeterKen Bennett / Wake Forest University

BI: How would you actually use it?

DC: Imagine you put this across the back of your phone. You hop in your car and let's say its a nice warm day.

And, the other thing this stuff does is if you flex it, if you make it vibrate, that also collects power. It is both piezoactive [in that it collects power from movement] and thermoelectric at the same time. It's essentially the only material that is, that I know of. So it's kind of cool.

So I hop in my car and my phone battery is running low. I'm going to drive from here down to Raleigh (North Carolina) which is about an hour and a half. I set this on my dashboard, the car vibrates — that generates power. And the dashboard's hot — that also generates power.  From both of those sources I collect additional power and soak that power into my battery. By the time I get into Raleigh my battery has about a 20 percent charge on it.  

It changes the way people use things. 

BI: Then all you would have to do in any situation is find some kind of heat source. Even in the wilderness or in an emergency?

DC: Exactly.

If I go camping and I have a campfire next to my tent and I lay my phone out there next to the campfire and I go to sleep, when I wake up, assuming no one has stolen my phone, I have a charged battery. So it absorbs energy from the power that surrounds it and puts it back into the battery.

These days if you are at the airport, you hunt around for the outlet to plug your computer or phone into. But it could be that's not what you hunt for. Instead you hunt for the heat register, because that is where your power source is. 

BI: What would you most like to see power felt do?

DC: That's an interesting question. I look at it kinda like the cellphones are right now. People think of cellphones, you remember when the Motorola RAZR ... we thought that was revolutionary? But the revolution didn't come until they got really smart. An iPhone is a revolution away from a RAZR.   

And it can do a lot of stuff. So smartphones became ubiquitous. They became invisible. You turn your alarm in your home on with it. You turn your car on with it. You look up stuff on Google. All your contacts are in it and you use it as a camera. It actually is integrated into your life. In a way that you don't expect, in a way that you don't always notice.

Well power is the same thing. Power exists all around you. I'm standing in my kitchen, and I have power electronics all around me. I've got a microwave oven, I have a stove, I have a refrigerator. All of these things are a part of my life in an invisible way. Power felt is really meant to be invisible.

The revolution it presents is more power — a power density greater than what we have today. So laptops last longer, electronics last longer, things like that. You use power differently; you expect to collect power from your surroundings. You recognize now that power can be soaked up and placed into your electronics, like a sponge would soak up water. So that new point of view, that new way of seeing the world, is what changes stuff.

Power isn't just the thing that comes out of the socket in your house anymore. It is something that you as an individual have access to. You now have a power-generating device in your hand. It doesn't store power; it makes power. That's what makes it different.

BI: So how long before I can become an off-the-grid human? How long will it be before some of these products come to market?

DC: We hope to have the first ones in the market next year. We are in the process of signing a contract with a company that is commercializing the stuff. That company has some fairly big backers behind it — large companies that you have heard of. I can't give names but let's just say the chances are extremely good that they make something that's in your house right now.