Energy

Some estimates peg the world's petroleum reserves being depleted in 100 years. Petroleum-based synthetic fibers, then, cannot be labeled "sustainable" or "renewable — even if they are recycled.

The cotton plant, too, yields much more than just the fiber we use to produce the clothes we wear; the cottonseed oil can be produced into biodiesel fuel, and the cottonseeds themselves are considered high-quality feed for cows and other ruminants. For typical yields in the U.S., seed production can result in over 20 gallons of biodiesel per acre — more than meeting its direct fuel use in growing and ginning the crop.