I've just finished the book, and was thinking that they use an awful lot of resources.  Recycling is a fine first step for waste and water, but successful cloning in vats, as well as the manufacture of crystals and who knows what else requires much greater resources I am sure.  They create steel weapons coated in copper and copper cannon.  Since they do not utilize the surface of whatever planet they are on, where do the raw materials for them come from?