Author(s): V. Yildiz; S. Brown; C. Rouge
Keywords: Hydropower optimisation; Run-of-River (RoR) hydropower plant; HYPER; Multiobjective Evolutionary Algorithms (MOEA); Capital and investment costs; Flow duration curve (FDC); Many-Objective Robust Decision Making (MORDM); Uncertainty analysis
Abstract: Hydropower is a comparatively cheap, reliable, sustainable, and renewable source of energy. Run of River (RoR) hydropower plants are characterised by a negligible storage capacity and by generation almost completely dependent on the timing and size of river flows. Their environmental footprint is minimal compared to that of reservoir-powered plants, and they are much easier to deploy. This work uses and extends HYPER, a state-of-the-art toolbox that finds the design parameters that maximise either the RoR plant’s power production or its net economic profit. Design parameters include turbine type (Kaplan, Francis, Pelton and Crossflow), configuration (single or two in parallel), and design flow, along with penstock diameter and thickness, admissible suction head, and specific and rotational speed. This work extends HYPER to realise hydropower system design that is robust to climate variability and change to changing economic conditions. It uses the many objective robust decision making (MORDM) approach through the following steps: (1) an explicit three objective formulation is introduced to explore how design parameter choices balance investment cost, revenue, and drought period (first percentile) revenue, (2) coupling of a multi-objective evolutionary algorithm (here, AMALGAM) with HYPER to solve the problem using 1,000 years of synthetic streamflow data obtained with the Hirsch-Nowak streamflow generator, (3) sampling of deeply uncertain factors to analyse robustness to climate change as well as financial conditions (electricity prices and discount rates), (4) quantification of robustness across these deeply uncertain states of the world. We also extend HYPER by adding the possibility to consider three-turbine RoR plants. The HYPER-MORDM approach is applied to a proposed RoR hydropower plant to be built on Mukus River in Van province which is located in Eastern Anatolia region of Turkey. Preliminary results suggest that applying MORDM approach to RoR hydropower plants provides insights into the trade-offs between installation cost and hydropower production, while supporting design with a range of viable alternatives to help them determine which design and RoR plant operation is most robust and reliable for given site conditions and river stream characteristics. Results confirm earlier findings that installation of more than one turbine in a hydropower plant enhances power production significantly by providing operational flexibility in the face of variable stream flows. When contrasting robustness of a design with its benefit / cost ratio, a classic measure of performance of hydropower system design which accounts only for revenues and cost, designs with the highest benefit / cost ratios do not necessarily perform well in terms of dry period revenue. They also show less robustness to both climate change (and associated drying) and to evolving financial conditions than the designs that do better balance average annual revenue with dry period revenue.