Development of Dalalven hydro power scheme in Sweden

The Dalalven hydro scheme is located in central Sweden. Fortum has in the scheme 50 dams and 35 hydro power plants producing 4TWh energy with a capacity of 970MW. The main reservoirs are Lake Siljan and Trangsletsjon with Trangslet dam, the highest earth-filled dam in Sweden. Development of the hydro scheme started 1878 with construction of four power plants for industry until 1930. From 1931 to 1974 15 power plants were built for increasing electricity consumption. De-regulation of the energy market in 1990s and EU environmental targets in 2000s resulted in the rehabilitation of ten power plants between 1990 and 2014 with increased annual energy production of 377GWh (29%) and capacity 124MW (59%). This energy decreases the annual CO2 emissions with 125 918 tons in comparison to production of the same amount of energy by coal. In several cases the rehabilitation was made in new power houses, allowing the development of the layout and technology of civil structures, and use of state-of-art equipment. Sweden uses the green certificate system, and 235G Wh of the energy received this certificate. Other environmental benefits come from use of the environmentally friendly Kaplan turbines and construction of some new fish pass. There are further plans to increase the spillway capacity of Trangslet dam and to rehabilitate eight power plant units. The possibilities of obtaining the Environmental licences for the rehabilitations has became challenging in the past years and green certificates are nowadays agreed only for increased energy.