Which of these is stored in a gasometer?

We stopped calling them gasometers decades ago. It was thought to be a misleading term, and was changed to gas holder. Now there is no coal gas being made, most of them have been demolished, and a few have been turned into leisure centres or preserved monuments.

We converted to natural gas from town gas from 1967 to 1977 here in the UK. The answer should've just read gas.