...you just find another one.
Some things just become more ambiguous, not clearer, the more you look into them. Mostly, to avoid these headaches, people either just accept things (like the frog who gets boiled without noticing that his future is changing for the worse as the heat under the pot is turned up very slowly), or they have beliefs that save them the trouble of thinking matters through.
So, recently Coca-Cola announced that they are going to go to a 100% bioplastic "plant bottle" which is made from plant materials instead of being petroleum-based. Right now, their bottles are already 30% made from such renewable feed stock (petroleum being, for a fact, despite the claims of scientists such as S. Palin, both finite and non-renewable). The other 70% is now PET plastic along with some chemicals for softening and flexibility. To make the project economically as painless as possible, they're partnering with a Wisconsin company, Virent, to refine the process of producing purer paraxylene from a byproduct of the biofuel production process. Other large packagers are on board, such as Heinz and Proctor & Gamble, as well as Ford, which has already pioneered use of recycled PET plastic for interiors. The Air Force is testing jet biofuel, and Honda and Shell Oil are in also. Big corporate environmentalism? Bring it on, since, let's face it, another article in the Sierra Club magine pushing the idea isn't going to move much on the global chessboard.
But then...using switch grass or plant leftovers sounds efficient and good, but what if the major source of plant feedstock for this new plastic turns out to be one of the major monocrops of industrial agriculture, such as corn? The effects of expanding its production on our battered, eroding soils or creating square miles of new sugar cane fields by bulldozing the Amazon basin even more would be as hard on the world environment as the PET plastics already are. That's more diesel fuel use, and more herbicides and pesticides, when we have far too much of that now. And the plant-based plastic might well include the same dangerous additive chemicals for softening that are currently used.
Recycling problems will not go away. The current rate with PET petroleum plastic bottles is only around 24% (except in states with refundable deposit laws, where it averages 70%), and the recycling industry is not set up to handle bioplastic. Coca-Cola and other giants oppose deposit laws, since that system requires some effort from them. In Europe, companies are being held accountable for accepting back their materials, even whole cars, but as long as one lobbyist draws breath in the USA, that won't happen here.
Dilemmas like this remind me of what Tony Soprano would say: "Well, whatcha gonna do?"