A toolbox for the optimal design of run-of-river hydropower plants

摘要

Hydroelectric power is a relatively cheap, reliable, sustainable, and renewable source of energy that can be generated without toxic waste and considerably lower emissions of greenhouse gases than fossil fuel energy plants. Conventional hydroelectric plants produce energy by the controlled release of dammed reservoir water to one or more turbines via a penstock. The kinetic energy of the falling water produces a rotational motion of the turbine shaft and this mechanical energy is converted into electricity via a power generator. Dam-based plants are among the largest and most flexible power producing facilities in the world, yet their construction and operation is costly and can damage and disrupt upstream and downstream ecosystems and have catastrophic effects on downriver settlements and infrastructure. Run-of-the-river (RoR) hydroelectric stations are an attractive and environmentally friendly alternative to dam-based facilities. These plants divert water from a flowing river to a turbine and do not require the formation of a reservoir. Despite their minimal impact on the surrounding environment and communities, the potential of RoR plants has not been fully explored and exploited. For example, in the United States it is estimated that RoR plants could annually produce 60, 000 MW, or about 13% of the total electricity consumption in 2016. Here, we introduce a numerical model, called HYdroPowER or HYPER, which uses a daily time step to simulate the technical performance, energy production, maintenance and operational costs, and economic profit of a RoR plant in response to a suite of different design and construction variables and record of river flows. The model is coded in MATLAB and includes a built-in evolutionary algorithm that enables the user to maximize the RoR plant's power production or net economic profit by optimizing (among others) the penstock diameter, and the type (Kaplan, Francis, Pelton and Crossflow) design flow, and configuration (single/parallel) of the turbine system. Unlike other published models, this module of HYPER carefully considers each turbine's design flow, admissible suction head, specific and rotational speed in evaluating the technical performance, cost and economic profit of a RoR plant. Two case studies illustrate the power and practical applicability of HYPER. Some of their results confirm earlier literature findings, that (I) the optimum capacity and design flow of a RoR plant is controlled by the river's flow duration curve, (II) a highly variable turbine inflow compromises energy production, and (III) a side-by-side dual turbine system enhances considerably the range of workable flows, operational flexibility and energy production of a RoR plant. HYPER includes a GUI and is available upon request from the authors.