Parametric analysis of pump-turbine sites

Although no new pump-turbine developments have been built on the North American continent since the Rocky Mountain 850MW facility was commissioned in 1995 (1), there is a renewed interest in their development, driven by the need to firm up energy derived from wind, run-of-river small hydro and coal developments as at North Eden, where a 700MW facility is planned (8). Currently, many developers are searching for sites, and recently 25 permits for 29,444MW of pump-storage have been issued in the USA (9). Designs have been developed for sites with underground storage, and others are investigating sites with relatively low head and long conduits. Such sites are likely to be uneconomic at current market prices for off-peak and on-peak energy. The HydroHelp 5 computer program has been developed to design and cost pump-turbine projects, and three examples of site costing are included, for Lake Uist in Nova Scotia, for Saguenay Fjord in Quebec, and for a theoretical site with a deep underground reservoir. To assist in the assessment task, a set of guidelines is desirable, to determine what site parameters have to be within such limits as - minimum head; maximum length of the water passages; minimum capacity and storage conditions; based on a given differential in energy costs, in order for the site to be economic. Using the computer program HydroHelp 5, a set of conditions has been developed for a variety of energy cost differentials using a fixed interest rate of 5%. Prospective developers can use the same program to develop their own particular set of conditions.