I'm very interested in how we can continue to manufacture the synthetic substances on which our civilization depends when oil runs out. I've long been aware of the possibilities of algae, lignin and lanolin and hope to write about them one day. Yesterday while reading Alistair Cooke's American Jouney I came across a new one:
That's right: oranges.
During World War II Florida chemist W. H. Schulz figured out so many uses for the detritus of juice production that the juice itself became almost a by-product.
Carotene to produce vitamin A and terpenes to make waterproof paint for battleships were extracted from the zest. The pith yielded pectin which was used as a gelling agent in the treatment of deep wounds. From the pulp they extracted cellulose which was converted into cellophane and ethanol. The cellophane was ued to make sturdy waterproof containers (some of which were then used to transport orange juice concentrate!). Some of the ethanol was used for fuel and the remainder was converted to butadiene and thence to synthetic rubber. Oil for margarine was extracted from the seeds and everything that was left was burnt to produce activated charcoal for gas mask filters.
Schulz's company is still trading, mainly producing the active ingredient in orange-oil based cleaning products.