Carbon dioxide is not manufactured so much as collected: it comes out of ammonia and fertiliser production, and in Britain most of it came out of two plants — one on Teesside, one in Cheshire — run by CF Industries, a US-owned fertiliser company. In September 2021, wholesale gas prices spiked, fertiliser production became unviable, and CF stopped. The CO2 was a by-product; the food industry was not its customer so much as its dependent.
The shutdown cut 60% of the UK's food-grade CO2 supply almost overnight. The gas carbonates soft drinks and beer, extends the shelf life of packaged meat and baby food, stuns pigs and chickens before slaughter, grows greenhouse cucumbers, and ships as dry ice to keep frozen food cold. Within days, supermarkets were warning of shortages of poultry, pork and bakery products, and the remaining supply was being prioritised for medical use.
The government ended up paying: on 21 September it agreed to cover the full operating costs of the Teesside plant for three weeks — tens of millions of pounds of public money to restart a private company's idle line. Food producers paid five times the old price, £1,000 a tonne instead of £200. Nobody had planned a food-system dependency on one supplier's waste stream; everyone discovered it in the same week.
The government paid tens of millions to restart one plant for three weeks; food producers paid £1,000 a tonne instead of £200, as by-product chains lack spare capacity.
A by-product economy has no spare capacity: when the primary product stops, the secondary one disappears with it, and nobody holds stock.
Sixty percent of a national input through two plants is a single point of failure wearing the disguise of an efficient market.
The price signal arrived too late to matter — gas prices made fertiliser unviable in days, and the food chain needed months of warning it never got.
Map the inputs your industry shares with someone else's business — a by-product supply chain is one price spike from becoming a national emergency, and the plant's owner answers to neither.
FOLLOW THE EVIDENCE