Application Multi-Objective Robust Decision-Making to the Design of Run-ofRiver Hydropower Plants
Authors: Yildiz Veysel , Rougé Charles , Brown Solomon 
Published: March 2021

&lt;p&gt;Hydropower is a comparatively cheap, reliable, sustainable, and renewable&lt;br&gt;source of energy. Run of River (RoR) hydropower plants are characterised by a&lt;br&gt;negligible storage capacity and by generation almost completely dependent on the&lt;br&gt;timing and size of river flows. Their environmental footprint is minimal compared to that&lt;br&gt;of reservoir-powered plants, and they are much easier to deploy.&lt;br&gt;This work uses and extends HYPER, a state-of-the-art toolbox that finds the&lt;br&gt;design parameters that maximise either the RoR plant&amp;#8217;s power production or its net&lt;br&gt;economic profit. Design parameters include turbine type (Kaplan, Francis, Pelton and&lt;br&gt;Crossflow), configuration (single or two in parallel), and design flow, along with&lt;br&gt;penstock diameter and thickness, admissible suction head, and specific and rotational&lt;br&gt;speed.&lt;br&gt;This work extends HYPER to realise hydropower system design that is robust&lt;br&gt;to climate variability and change and to changing economic conditions. It uses the many&lt;br&gt;objective robust decision making (MORDM) approach through the following steps: (1)&lt;br&gt;an explicit three objective formulation is introduced to explore how design parameter&lt;br&gt;choices balance investment cost, average annual revenue, and drought year (first&lt;br&gt;percentile) revenue, (2) coupling of a multi-objective evolutionary algorithm (here,&lt;br&gt;AMALGAM) with HYPER to solve the problem using 1,000 years of synthetic&lt;br&gt;streamflow data obtained with the Hirsch-Nowak streamflow generator, (3) sampling&lt;br&gt;of deeply uncertain factors to analyse robustness to climate change as well as financial&lt;br&gt;conditions (electricity prices and interest rates), (4) quantification of robustness across&lt;br&gt;these deeply uncertain states of the world. We also extend HYPER by adding the&lt;br&gt;possibility to consider three-turbine RoR plants.&lt;br&gt;The HYPER-MORDM approach is applied to a proposed RoR hydropower plant&lt;br&gt;to be built on Mukus River in Van province which is located in Eastern Anatolia region&lt;br&gt;of Turkey. Preliminary results suggest that applying MORDM approach to RoR&lt;br&gt;hydropower plants provides insights into the trade-offs between installation cost and&lt;br&gt;hydropower production, while supporting design with a range of viable alternatives to&lt;br&gt;help them determine which design and RoR plant operation is most robust and reliable&lt;br&gt;for given site conditions and river stream characteristics. Results confirm earlier&lt;br&gt;findings that installation of more than one turbine in a hydropower plant enhances&lt;br&gt;power production significantly by providing operational flexibility in the face of variable&lt;br&gt;streamflows. When contrasting robustness of a design with its benefit / cost ratio, a&lt;br&gt;classic measure of performance of hydropower system design which accounts only for&lt;br&gt;annual revenues and cost, designs with the highest benefit / cost ratios do not&lt;br&gt;necessarily perform well in terms of dry year revenue. They also show less robustness&lt;br&gt;to both climate change (and associated drying) and to evolving financial conditions&lt;br&gt;than the designs that do better balance average annual revenue with dry year revenue&lt;/p&gt;