There's apparently no end to the sheer inventiveness displayed by researchers and the industry when it comes to putting the 'bio' into biopolymers. Orange peel, peat, tannery waste, sewerage sludge, insect cuticle-you name it, if it's biological in origin, you can be sure that somebody, somewhere has tried turning it into a biogases polymer.
Right now, it's algae that are once again grabbing the headlines. Algae are plentiful, tend to grow fast and do not compete for land with food crops. They can be cultivated in extremely adverse conditions. They devour CO2, as much as they can get, and in the process they give off oxygen. In fact, those in the know will tell you that the stuff most people think of as seaweed or slimy green pond scum actually function as fantastically efficient mini-biofactories....