Study on the development of pumped storage hydropower project at Snåsa

Abstract

An increasing power demand and a transition towards more renewable energy sources have led to an increasing development of wind farms. Wind farms produce unregulated power which may not be available when it is needed. Pumped storage power plants can have a stabilizing effect of the power grid as well as increase the utilization of the wind power by using surplus power to store water and produce power from this water when needed.The two lakes Ytter-Bangsjøen and Snåsavatnet is suited for a pumped storage power plant. With the construction of a 1 km low dam the magazine capacity is increased to 260 mill m3 and a head of 296.8 m. The water tunnels that s need constructing will have a total length of 6.5 km which because of good rock quality and topography can be unlined. A review of the topographic and geological conditions was done for the area, and the underground elements was located and orientated on basis of these findings in the area. The headrace and tailrace tunnel was optimized towards an economical optimum, based on net present value and given values for the power price.The selected tunnel profile and the power cavern were simulated with the finite element software Phase2 to investigate the stability of the openings. Results showed that only a 70 m stretch of limestone needs support.The construction costs was calculated using NVE cost base for hydropower plants and gave a cost of 1122 mill NOK. For calculating profitability a series of sale power prices was set, and for each value a corresponding maximum buy price that gave a positive NPV was found. The result gave an equation that found the price variation in the power market to be too small for the project to be profitable from operating solely on the power market, and should rely on buying surplus wind power.