A great article from GreenBuildingAdvisor.com about recycling carpet: "Green Up Your Carpet Life-Cycle."
Because recycling options are not immediately available, about 2.5 million tons of carpet end up in landfills, according to Peter Yost and Amy Hook.
Yost and Hook state that "In 2002, the carpet industry, key government agencies, and non-profit environmental organizations, created the Carpet America Recovery Effort (CARE). CARE has always had ambitious goals for carpet diversion, starting with 40% by 2012. CARE’s latest report shows a total diversion rate in 2009 of around 25%. There are currently 72 CARE reclamation partners in the US." See the interactive CARE map to find a reclamation partner. (Recovery 1 Resource Recovery, Recycling Center and Research Facility is located in Tacoma, WA)
Yost and Hook give great suggestions for lessening your carpet impact. One is using carpet tiles, which can be easily replaced. Or, they could easily be traded out (i.e., bought/sold on Craigslist) because tiles are a standard size and not custom cut to fit a room). FLOR offers natural wool carpet squares.
Wool Carpet Squares: FLOR's Lamb Chord in Gotland Gray
I discussed Auburn University's Rural Studio's Lucy/Carpet House in a past blog post on salvage.The house contains 72,000 stacked tiles. They were new, so they had to be placed in storage for 7 years to off-gas. Used carpet could be utilized in this way without the off-gassing issue. I love the book covering their early projects, "Rural Studio: Samuel Mockbee and the Architecture of Decency" by Andrea Oppenheimer Dean and Timothy Hursley. If you like creative solutions to affordable housing, this book will make you long to live a place without building codes.
Lucy/Carpet House, Mason's Bend, AL. Photo credit here.