Cost estimates for hydropower at existing dams

Guidelines for quick and simple hydropower project cost estimates are developed for preliminary site assessments. The guidelines are based upon a concept which incorporates a single equation utilizing design power and head for total equipment cost and a "site factor" to determine total project cost. Total project cost is estimated by multiplying the equipment cost, obtained from the equation, and the site factor. Total project cost data from a number of hydropower projects are compiled to provide guidelines for choosing the site factor, which is shown to vary greatly, especially for micro (≤100 kW) and mini (≤1,000 kW) hydropower projects. Envelope curves for site factors are given, and a "weighting factor," which is the fraction distance between upper and lower envelope curves, is chosen for each site. The choice of weighting factor for a given site is based upon comparison with recently completed projects, a knowledge of the components which can greatly increase civil works costs, and engineering judgement. The weighting factor is then used in calculations to determine optimum plant capacity. The methodology was used in a survey of the hydropower potential at existing Minnesota Dams, which is presented as a case study.