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

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