IT HAS become one of those great festive clich茅s, like granny falling asleep in front of the telly. No matter how modest the bird you buy, your family and friends can never polish it off, and you spend days eating the leftovers.
Leftovers are an even bigger problem for the people who provided your bird in the first place. At this time of year, the world is faced with mountains of unwanted, unpalatable poultry. And I do mean unpalatable: the real problem isn鈥檛 the scraps on your table, but feathers. Millions of tonnes of them are plucked from chickens and turkeys every year, and they鈥檙e too filthy even to throw away. But fortunately scientists are cooking up recipes even more creative than turkey and chanterelle mousse, and finding ways to turn this unprepossessing ingredient into materials like no other.
The poultry industry used to process the feathers and put them into low-grade animal feed, but thankfully this enforced cannibalism has now become illegal in Europe, and is increasingly unpopular in the US. 鈥淚t raises the spectre of mad chicken disease,鈥� says Richard Wool of the University of Delaware in Newark, an expert in the field of green materials. And because of a recent law, feathers can鈥檛 be dumped in the EU.
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In abattoirs, feathers are rubbed off the birds, taking blood and bits of skin with them. They then fall into a water flume that cycles around the abattoir, breeding bacteria all the time. By the end, they are so contaminated that they cannot be put into landfill until they have been sterilised. 鈥淭hat seems like a big cost just to throw them away,鈥� says Stephen Woodgate, technical director of the European Fat Processors and Renderers Association.
So why not put them to use? It is potentially a huge resource 鈥� the US produces more than a million tonnes of chicken feathers a year, for example. That鈥檚 rather too many to stuff into pillows, and it鈥檚 not easy to think of other uses for these short, fluffy feathers. Very small dusters? Feather boas for Barbie dolls?
Several teams are working on a rather more sensible idea: trying to take the fibres from poultry feathers and turn them into some kind of fabric. Among the leaders are a team led by Walter Schmidt of the US Department of Agriculture in Maryland, and an EU-funded project called Hipermax. Woodgate is their feather science coordinator.
The first step is to give the raw feathers a really thorough clean. Schmidt鈥檚 team and others at Philadelphia University in Pennsylvania and Auburn University in Alabama have tried solvents such as ether, but scaling that up may be expensive or even dangerous. Woodgate believes a better approach is to use water and soap, plus some choice enzymes 鈥� essentially a kind of fine-tuned washing machine technology.
Once the feathers are clean, their fibres must be stripped off the stiff central quills. Schmidt鈥檚 team has developed a machine to align the feathers and cut them parallel to the quills. A turbulent airflow then lifts up the light fibres, letting the heavier quills drop out. As an alternative, a group in Jordan has suggested freezing feathers in liquid nitrogen and then crushing them.
Plucking ingenious
One obvious use for the fibres is fabric, but they are too short to be spun into yarn and woven or knitted. Making feather cloth needs a little more ingenuity. The US groups mix the dry feather fibre with synthetic thermoplastic strands to form a web of material that is then heated to melt the plastic and glue the whole lot together.
Not surprisingly, the prototype fabrics have good insulating properties, so they might end up in high-performance skiwear, or be used for insulating buildings. They are also highly absorbent, making them potentially suitable for filtering heavy metals from waste water, or absorbing oil spills. And because these fabrics are biodegradable, they could be laid on the ground to fight soil erosion.
Wool has a more adventurous plan for surplus feathers. He鈥檚 an expert in devising green materials, often using agricultural raw materials. 鈥淚n Delaware, our two main products are soybeans and chickens, so one summer I said for the fun of it, why don鈥檛 we make an all-Delaware product from feathers and soybeans?鈥�
But what to make? Wool realised that the feathers have a special ingredient that could be very useful in a circuit board: air. Although electrical signals travel only through the copper wires printed onto a circuit board, they are slowed down by the material underneath. Charges in the molecules of the board are tugged about by the electrical pulse in the copper, and they tug back. Air hardly does this because its density is so low. So if you can pack air into a circuit board, you speed it up.
Wool鈥檚 group set their feather fibres in a resin derived from soybeans. 鈥淲e get a wonderfully strong material,鈥� he says. 鈥淚t鈥檚 also artistically lovely, as the feathers are embedded in something like a plexiglas matrix.鈥� And signals travel across it about 40 per cent faster than on standard circuit boards. Wool says that Intel is interested.
What鈥檚 more, the fact that the fibres are long and thin means that if the temperature goes up, the expanding air can escape instead of breaking the board. The composite hardly expands when heated, and it鈥檚 light, which could make these circuit boards appealing to the aerospace industry. Who knows, one day chicken feathers might actually fly.
Wool is also working on turning feathers into cars. Feathers are made of the protein keratin, a carbon-rich polymer whose long molecules are highly aligned. When it is heated to a few thousand degrees in a nitrogen atmosphere, the keratin turns into strong carbon fibre. Wool says his early samples are as strong as conventional carbon fibres made from more expensive ingredients, and because the feathers retain their hollow structure, the material is light. It could be cheap and strong enough to turn into car parts.
Because feathers would replace less renewable resources, these schemes will almost certainly have an environmental benefit. As feathers have to be cleaned anyway before disposal, they are an environmentally friendly, free raw material. Wool calculates that every kilo of soybeans used in his circuit boards would save about a kilo of fossil fuel.
鈥淔eather fibres might end up in circute boards, or be used as car or aircraft parts鈥�
The ethical downside is that most or all of the feathers would come from factory-farmed poultry, making an unpleasant industry even more profitable. And of course, many vegetarians would be unhappy to find processed turkey and chicken feathers turning up in clothes, cars and all kinds of electronic goods. Chris Olivant, spokesman for the UK鈥檚 Vegetarian Society, says that although they wouldn鈥檛 recommend feather-based products to their members, they wouldn鈥檛 actively campaign against them. 鈥淲e have better things to do,鈥� he says.
But perhaps the angst-ridden among us will be able to choose organically sourced featherware. Then one day you might be able to slip on those feather salopettes and drive your feather-chassis car to the ski slopes 鈥� assuming global warming hasn鈥檛 rid them of snow. But if it has, maybe feathers would make a good substitute.