Gasholders

Gas holders, also known as gasometers, are large storage structures once used to hold town gas produced at a gasworks. A typical gas holder comprises a fixed outer shell that holds a water-filled chamber and a movable inner gas-tight vessel, the gas holder or bell, which rises and falls as gas is stored or withdrawn.

Gas is stored at near atmospheric pressure by water displacement; as gas is produced, the inner bell rises, displacing water. When gas demand increases, the bell lowers and gas is drawn from the storage into the distribution network. The water surrounding the bell acts as a seal to prevent air ingress and to contain the gas safely.

Gas holders were a standard feature of coal-gas-based utilities in the 19th and early 20th centuries, common in the United Kingdom, Europe, and North America. They varied in size, often holding tens to hundreds of thousands of cubic meters of gas. With the introduction of natural gas and modern storage technologies, many holders were decommissioned and removed in the late 20th century, though some remain as historical landmarks or have been repurposed.

Today, surviving gas holders are sometimes preserved as industrial heritage sites or repurposed for housing, offices, or cultural venues. Their distinctive skyline presence remains a reminder of the era of coal gas and early urban energy networks.