Our recent H-HOPE report presents a comprehensive evaluation of the project’s progress, focusing on the design, modelling, and testing of three configurations tailored to specific environments.
The H-HOPE energy harvester is being developed in three distinct configurations, each tailored to meet the specific technical requirements of its intended application—piping systems (PP), open streams (OS), and open channels (OC). These configurations are designed to address factors such as installation characteristics, maximum technology size, and flow conditions unique to each environment.
For each configuration, a one-dimensional (1D) hydraulic-mechanical-electric numerical tool has been developed. This tool is used for the preliminary design of the harvester, helping to estimate key characteristics such as mass, damping, and stiffness, as well as to understand the interactions between the mechanical and electrical components. In some cases, multiple design options were explored for each configuration to identify the most suitable approach.
Below, we summarise the key findings from the report, shedding light on the outcomes for each configuration and their implications for future development.
1. Piping Systems (PP)
Piping systems posed unique challenges due to low flow velocities and dimensional constraints. Two options were developed to address these issues:
- PP-OP1: Hydrofoil with Piezoelectric Patches
In this design, a vibrating hydrofoil was immersed in the fluid and piezoelectric patches were placed on the hydrofoil to maximize power generation, with the best results achieved by positioning them closest to the clamped end of the wing. While effective, this option faced challenges in maintaining lock-in conditions under the low flow velocities typical of piping systems
PP-OP2: Cylinder with Cantilever
In this design, a vibrating cylinder caused by vortex shedding induced bending motion in a cantilever, which was converted into electrical power through piezoelectric patches.This configuration demonstrated the ability to effectively harvest energy from vortex-induced oscillations in water distribution pipes. The design showed strong potential for real-world applications, especially in retrofitting existing water networks.
2. Open Streams (OS)
Energy harvesting from open streams introduced new opportunities but also revealed design-specific limitations.
OS-OP1: Elastic-Mounted Cylinder
This system effectively converted cylinder oscillations into electrical energy via a linear generator, achieving a 62% efficiency in initial tests. Building on concepts from the PP-OP2 design, it adapted well to the open stream environment, highlighting its flexibility and potential for deployment in various site conditions.OS-OP2: Fixed Cylinder with Flexible Membrane
Unlike OS-OP1, this configuration underperformed. While the membrane deformed in response to vortex shedding, the resulting mechanical power and energy conversion efficiency were too low for practical use. The damping effects of piezoelectric patches further reduced output, leading to the conclusion that this option was not viable for further exploration.
3. Open Channels (OC)
For open channels, where no walls are available to support the harvester, one configuration was tested:
- OC-OP1: Cylinder and Vibrating Membranes
This system utilized vortex shedding to induce cross-flow oscillations in a translating cylinder while generating additional energy through downstream vibrating membranes. Computational models validated the interactions between the cylinder and membranes, confirming the feasibility of energy harvesting in open environments. However, optimizing the membranes’ properties and coupling them with the generator remains a challenge to improving overall efficiency.
Key Insights and Challenges
Strengths:
- The multiphysics modeling approach accurately predicted system behaviors, enabling targeted optimisation for each configuration.
- Configurations such as PP-OP2 and OS-OP1 showed strong potential for practical applications in their respective environments.
Limitations:
- OS-OP2 was deemed unsuitable for further investigation due to its low power output and inefficiencies.
- While promising, OC-OP1 requires additional refinements in material selection and system integration to achieve higher performance levels
The findings set the stage for detailed 2D and 3D simulations, which will focus on validating fluid-structure interactions and refining electrical models. These efforts, detailed in the upcoming Deliverable 4.2, aim to further optimize configurations with the most potential and continue the development of the energy harvester.
