The Tummel Bridge hydro power station in Scotland has been generating renewable electricity since 1933, and it recently finished its first major upgrade in 90 years. The two main turbines were replaced as part of a renovation project that will extend the plant’s operational life by at least 30 years. The new turbines will increase capacity by 30% and will provide clean electricity for over 20,000 homes. This station is part of a system that was conceived in the early days of electricity distribution. Tummel is one of nine small-scale power stations that were built in the early 1930’s. All of them are powered by a vast system of dams. A five kilometre long open water channel carries water from a large reservoir. The water rushes downhill through two huge pipes that connect to the power stations. The head of the renovation work says that the system is a glowing testament to the engineering capabilities of the 1920s and 30s. "It shows a huge understanding of what they were trying to do. The precision and the detail that they accomplished with hand tools and basic technology was really quite amazing."