Gas storage tanks. Supporting structures of three gas storage tanks and two electricity pylons and power lines silhouetted against a setting sun. These large cylindrical tanks are sometimes called gasholders or gasometers. The actual storage tanks (not seen) are telescopic, and their height above ground varies with the amount of gas in them. The gas level here is low, and only the framework that supports the full tanks is seen. The gas stored is obtained from natural gas, and used as a household and industrial fuel. The pylons carry power lines that distribute electricity. Gas and electricity are the main sources of household energy.