Application Multi-Objective Robust Decision-Making to the Design of Run-ofRiver Hydropower Plants

Hydropower is a comparatively cheap, reliable, sustainable, and renewablesource of energy. Run of River (RoR) hydropower plants are characterised by anegligible storage capacity and by generation almost completely dependent on thetiming and size of river flows. Their environmental footprint is minimal compared to thatof reservoir-powered plants, and they are much easier to deploy.This work uses and extends HYPER, a state-of-the-art toolbox that finds thedesign parameters that maximise either the RoR plant"s power production or its neteconomic profit. Design parameters include turbine type (Kaplan, Francis, Pelton andCrossflow), configuration (single or two in parallel), and design flow, along withpenstock diameter and thickness, admissible suction head, and specific and rotationalspeed.This work extends HYPER to realise hydropower system design that is robustto climate variability and change and to changing economic conditions. It uses the manyobjective robust decision making (MORDM) approach through the following steps: (1)an explicit three objective formulation is introduced to explore how design parameterchoices balance investment cost, average annual revenue, and drought year (firstpercentile) revenue, (2) coupling of a multi-objective evolutionary algorithm (here,AMALGAM) with HYPER to solve the problem using 1,000 years of syntheticstreamflow data obtained with the Hirsch-Nowak streamflow generator, (3) samplingof deeply uncertain factors to analyse robustness to climate change as well as financialconditions (electricity prices and interest rates), (4) quantification of robustness acrossthese deeply uncertain states of the world. We also extend HYPER by adding thepossibility to consider three-turbine RoR plants.The HYPER-MORDM approach is applied to a proposed RoR hydropower plantto be built on Mukus River in Van province which is located in Eastern Anatolia regionof Turkey. Preliminary results suggest that applying MORDM approach to RoRhydropower plants provides insights into the trade-offs between installation cost andhydropower production, while supporting design with a range of viable alternatives tohelp them determine which design and RoR plant operation is most robust and reliablefor given site conditions and river stream characteristics. Results confirm earlierfindings that installation of more than one turbine in a hydropower plant enhancespower production significantly by providing operational flexibility in the face of variablestreamflows. When contrasting robustness of a design with its benefit / cost ratio, aclassic measure of performance of hydropower system design which accounts only forannual revenues and cost, designs with the highest benefit / cost ratios do notnecessarily perform well in terms of dry year revenue. They also show less robustnessto both climate change (and associated drying) and to evolving financial conditionsthan the designs that do better balance average annual revenue with dry year revenue