Dynamic Tidal Power

Abstract

In 2008, a new concept to extract tidal energy was introduced called Dynamic Tidal Power (DTP). In this concept, the natural tidal wave propagating along a coastline is blocked using a long dam, inducing a water level difference between both sides of the dam. This water level difference, called the hydraulic head, can be exploited by placing turbines inside the dam. This is a promising concept, but the feasibility and suitable locations for DTP are largely unknown yet.

This study aimed to identify locations that have the highest potential to implement the DTP concept. By investigating the feasibility criteria and their influence and translating these criteria to spatial analysis, geographic regions with high potential were identified. Additionally, linkage opportunities were assessed and identified to possibly improve the feasibility of DTP.

Based on a sustainable feasibility study framework, the key aspects can be categorized into three main categories; technical, economic and social-ecological feasibility. These aspects were translated into criteria, whose influence was investigated using a hydraulic model. Considering the technical criteria, the tidal flow velocity proved to be more influential on the feasibility than the depth, finding weighting factors of 0.87 and 0.13, respectively. In order to define a threshold of the feasibility of DTP, the technical and economic criteria were combined by assessing the upper threshold of the Levelized Costs Of Energy (LCOE) of 0.1 €/kWh to find a minimum required average flow speed of 0.63 m/s. This threshold was used in the spatial model. The island linkage opportunity proved to be highly valuable. Connecting an island increases the effective blockage length, resulting in a hydraulic head and power output increase with approximately the same dam construction costs. This lowers the mean tidal current speed required for feasibility to 0.39 - 0.57 m/s.

The spatial analysis used a Multi-Criteria Weighted Overlay Analysis (MCWOA) approach, combining datasets and weighting factors for each criterion to find a total Potential Index (PI) score. In total 41 potentially feasible locations for DTP were identified. The geographic regions with the highest potential to implement DTP are the Yellow Sea, the seas in Southeast Asia, and the seas of Oceania. This is due to a combination of high tidal current velocities, relatively modest water depths and a good combination of secondary criteria (energy usage, population size & low shipping disruption). A high share of the island linkage opportunity was found in the locations with the highest potential (44%). It is recommended to investigate whether additional island linkage opportunities can be identified, by lowering the tidal current velocity threshold in the spatial model. Additionally, 233 locations were discarded, mostly due to their remote location. However, since these locations are technically feasible, it is recommended to investigate the possibility of transmitting the energy over long distances using Ultra High Voltage Direct Current transmission lines and study the total feasibility of DTP at these remote locations.

This study assessed the feasibility of DTP and identified that the Yellow Sea, the seas in Southeast Asia, and the seas of Oceania have the highest potential for a DTP project. Additionally, it provided new insights regarding the influence and thresholds of certain influential criteria, and it presents a hydraulic model and GIS tool that can be adjusted based on the preference of the user. These findings could be useful in future research on the DTP concept.