Companies such a Procter and Gamble still produce glycerol as a by-product of soap manufacture but the increased use of detergents is limiting the source. They developed commercial scale production of glycerol from yeast by fermentation in the presence of bisulfite, which reacts with acetaldehyde and prevents its conversion to ethanol. Subsequently, other commercial strategies have exploited the natural production of glycerol by yeast and other organisms in response to osmotic shock. During World War II, a chemical synthesis of glycerol from propylene, a petroleum product, provided the glycerol needed for explosives. Like the choice between guns and butter, yeast offers either glycerol or alcohol as war or peace alternatives.
Petroleum reserves are limited.
Even with conservation and recycling, sooner or later and perhaps within our lifetimes, demand will exceed supply. The consequences will affect all aspects of industrialized society - international relations, transportation, food production and distribution, urban planning, housing, and manufacturing. On the scale of things, the industrial production of glycerol from petroleum is minor. However, it symbolizes many of the issues associated with renewable resources and sustainability of contemporary society.