IRA FLATOW, host:
This is SCIENCE FRIDAY from NPR News. I'm Ira Flatow. As Congress debates energy policy, there is no shortage of alternative energy ideas, some that get lots of attention. You know them: solar, wind, stuff like that. Others you don't hear much about. They get lost in the journals, or they're confined to the backwaters of the Internet.
Well, this hour we're going to talk about new thinking in one conventional alternative energy, wind power, and new ideas in really alternative-alternative energies, like this first one.
My first guest has come up with a new approach to storing hydrogen to power fuel cells, for example. Here's the recipe. You take billions of chicken feathers, chicken feathers. You remove the quills, and then you cook the feathers, but don't cook them so much that you burn them. And what does that do?
Well, after they're cooked, the heating makes little nooks and crannies in the feathers that are perfect for storing hydrogen. The cost is low, of course, because the feathers are a byproduct of the chicken industry. You get them for next to nothing.
Here to tell us more about the promise of feathers and fuel cells is Richard Wool. He's a professor of chemical engineering at the University of Delaware. He and his colleagues presented this research at the Green Chemistry and Engineering Conference this week. He joins us from his office in Newark. Welcome to the program.
Professor RICHARD WOOL (University of Delaware): Hi, Ira, pleasure to be on your show.
FLATOW: Thank you. Did I describe that recipe correctly?
Prof. WOOL: That was a very good introduction. We do indeed take the chicken-feather fiber and we heat it up and we make all these nano-pores that hydrogen likes to absorb on, and so this is potentially a very cheap substrate for future generation cars, car tanks that will be used in the automotive industry.
FLATOW: How do you get the hydrogen into the feathers?
Prof. WOOL: You put it in under pressure and preferably at reduced temperatures.
FLATOW: And it just soaks it up into those pores?
Prof. WOOL: It soaks it up. It's a well-known fact that carbonatia(ph) substrates and other chemical substrates like metal hydrides like to fizz-absorb hydrogen, and so the trick is to get a very, very high surface area.
The problem with hydrogen, because it's a gas, it likes to occupy a lot of space, and it's a very, very light gas, so it has a very low energy density, and the whole trick here is to basically turn hydrogen gas into a two-dimensional solid by basically trying to absorb it as a carpet on the internal surface area of your substrate. And that's what people do with carbon, that's what they do with metal hydrides, and that's what we do with the chicken-feather fiber, which is a keratin fiber. And there is also an optimal pore size of the order of eight angstroms.
These are like little tunnels that the hydrogen likes to be in. It's a form of potential-energy entrapment of the hydrogen in these tunnels.
FLATOW: So you're making almost a perfect vessel for holding hydrogen out of the chicken feathers.
Prof. WOOL: Yes, and you know, the microstructure of these bird feathers really facilitates the development of these perfect tunnels.
FLATOW: And how does this approach compare, let's say, to other proposed hydrogen-storage devices?
Prof. WOOL: There are other very good hydrogen-storage devices out there, but the problem is that the majority of them are very, very expensive, and you know, people have examined, for example, carbon nanotubes, multi-wall carbon nanotubes. They have looked at metal hydrides, different chemical hydride systems.
There is a beautiful DOE program that is currently ongoing doing this, but if you look at the reality of the price of your gas tank on the ground, it is a bit mind-numbing to see the price of a gas tank made of carbon nanotubes.
And so the one thing that we have going with us for the chicken feathers is that it is very, very cheap, but it also addresses a disposal problem for these chicken feathers in the first place. There are six-billion pounds of them being generated by the poultry industry in America, and more abroad, and so what to do with these?
And this was part of our green-engineered materials program at the University of Delaware, where we are building new green materials for the renewable-energy infrastructure, and this is a highly energy-intensive system. I know your next speaker is going to talk about wind, but, you know, the wind blades and the rest are going to require an enormous amount of materials, and that's how we got going with the chicken feathers, to see if we can make high-performance materials. Just like we make now printed circuit boards for the electronic-materials industry out of chicken feathers and soybeans, the windmill blades in the future will also be made out of soybeans and carbonized chicken feathers, where we use them for carbon fiber.
Then came along the question: What about the hydrogen infrastructure? If these are so cheap, can we get the kinds of surface areas that we want at a very reasonable cost that can store adequate amounts of hydrogen? And we are heading strongly in that direction.
FLATOW: Wow, all from - all this stuff you can make out of chicken feathers.
Prof. WOOL: It's an amazing piece of material, and it has evolved over millions of years, and of course the, you know, birds have a rather unique evolutionary pathway. They can't afford to have a bad hair day, I suppose, and the materials that they develop over the - that have evolved for them over the years are really quite extraordinary, and so we use them in hydrogen storage and in other very high-performance composite applications.
FLATOW: So you're saying instead of using carbon nanotubes, you can carbonize the chicken feathers and make the same kinds of products out of them.
Prof. WOOL: Yeah. Our chicken feathers have approximately the same type of hydrogen absorption as the carbon nanotubes. Carbon nanotubes would be expected to be a little better, particularly pure, single-walled, carbon nanotubes, and these are amazing materials, but extraordinarily expensive.
We use them quite a bit in my own research group. So - but getting the chicken feathers pyralized(ph) to generate these little nano-pores is really the key for us and getting high internal surface area. These fibers, most of your listeners will know this as down. You know, eider down, the hairs from a duck. Well, this is chicken down, and these are basically hollow cylinders, and so in the future we'll be able to fill the hollow cylinders with additional materials that will be absorbing along with the type of fractal porous walls that we build into the walls of these micro-crystalline keratin fibers.
FLATOW: So how do you get the hydrogen out of the chicken feathers in your hydrogen tank?
Prof. WOOL: One important way. It goes in under pressure. Typically, we use pressures of the order of 40 or 50 bars, and you might say, well, what does that correspond to? Well, Daimler-Chrysler is using compressed-hydrogen tanks with 700 bars in there at the moment. So that's a very, very low pressure compared to what one can actually do with a gas.
And so you put it in under what I call low to moderate pressures, and then the hydrogen goes into the pores, and it absorbs, and then you can just de-pressurize it the same way you'd let the air out of a balloon, and that would deliver it to your fuel cell, and then you can recharge it again when it goes down.
FLATOW: How close, you know, to any kind of practical device are you now? Can you actually demonstrate it? Are people interested in this, or are they just laughing at the chicken feathers?
Prof. WOOL: No, people are interested in it, but there is quite a bit of research going on through NRIL(ph) at DOE, looking at several other technologies that are currently being examined by the automotive industry and others.
So at the moment I would say that the development of the fuel cell is one line of approach, and people are saying show us your cheapest and best storage device that comes along, and then the storage people are also pursuing this. So there are various levels of integration with the different technologies along the way, but the key issue at this point is to get the long-lasting fuel cells developed, and then different hydrogen-feed systems will come along, either compressed gas, you know, which is what Daimler-Chrysler is doing, and GM is looking at that, or there will be a metal-hydride case, as already exists to a certain extent, and then, you know, maybe someone will say let's explore the chicken-feather tank.
FLATOW: How big a tank would it have to be, or would it be - you know, would you have to replace the chicken feathers at a fueling station, or you refill them with hydrogen?
Prof. WOOL: You would refill it at a hydrogen station once the hydrogen infrastructure is set up, and so you are talking about if the DOE standards of six percent by weight and appropriate volumes are met, then you're talking about something close to your normal 20-gallong tank.
On the other hand, if we're at about a third of that or a fourth of that, then you're talking about something closer to, you know, 60 to 80-gallon tanks, which would not be an unreasonable thing to scale up at very, very low cost.
The hydrogen would go in, and it would be stored.
FLATOW: And you're saying that you can use chicken feathers, this technology, for other materials too.
Prof. WOOL: Yes. We have a significant program involving GM centers, a multinational, multi-university-proposed center at Delaware, to develop the green materials for the renewable-energy infrastructure.
For example, a windmill blade, a turbine blade, about 60 meters long, you can make that out of soybeans and natural fibers and these chicken feathers. Or electronic materials that are going to go into your future Dells can be made of soybean oil and these fibers for reinforcement.
So this has been an ongoing program with companies whose names you would well recognize, and so that is to clean up the carbon footprint of the electronic-materials industry. So that's a very, very nice application.
But composites in general: Supposing you wanted your car body made out of this, supposing you wanted, you know, that sleek sports car made out of green materials, then this is one way to do it.
FLATOW: All those billions of pounds of chicken feathers.
Prof. WOOL: It's quite a supply, and they are basically for free at this point.
FLATOW: Yeah, well, good luck to you. Thank you very much for taking time to talk with us.
Prof. WOOL: Thank you very much. It's been a pleasure to be on your show.
FLATOW: You're welcome. Richard Wool, who joined us from his office in Newark, Delaware. He and his colleagues presented his research at the Green Chemistry and Engineering Conference, and interesting work, chemical engineering, at the University of Delaware.
We're going to take a break, come back and talk more about alternative energy. We're going to talk about a new study of the potential of wind power. This study by the - published by the National Academy of Sciences, I wrote on my blog it blew me away, but it certainly did, about how much the potential there is for wind power as an alternative energy. We'll talk about the amazing amount of wind there is around the world that could solve a lot of energy problems if we can actually boot it up. So stay with us. We'll be right back after this break.
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