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Flexible Materials with Distributed Energy Converters

NREL is developing a new domain of technology to harvest ocean energy through use of flexible materials with embedded distributed energy converters.

An ocean energy converter, based upon flexible materials, with many relatively small energy converters distributed throughout, is a device whose flexible dynamic structural deformation (e.g., stretching, twisting, distending, bending, etc.) is energy available for harvest by those same embedded distributed energy converters. In this way, the distributed energy converter system can harvest ocean energy through active damping of the flexible material structure's ocean-induced deformations. Flexible Material Distributed Energy Converters (FMDECs) represent a technology domain that combines flexible materials—enabling continuous structural deformation—and embedment of distributed energy converters—enabling active damping of the structural deformations.

FMDECs are absent of discrete joints and hinging mechanisms. An FMDEC's individual energy converters are "power take-off units" leveraging the physics necessary to take dynamic structural deformation as input, and output electricity. Power take-off units can be any technique capable of damping or actuating motion within a flexible structure; dielectric elastomer generators are one example. By leveraging these features, FMDEC technology is capable of converting ocean energy into electricity throughout its structure—wherever ocean energy causes dynamic deformation of said structure, electricity can be generated directly.

An illustration of three flexible material distributed energy converter concepts, including flexible hull inertial point absorber, flexible line absorber, and flexing bottom fixed ocean energy converter.

Illustrations of three flexible material distributed energy converter concepts. Left: Flexible hull inertial point absorber. Center: Flexible line absorber. Right: Flexing bottom fixed ocean energy converter.

Activities

Structured Innovation

NREL actively develops and supports structured processes for innovating FMDPC technology and aims to develop and deliver FMDEC seedling concepts to the broader marine renewable energy community. See WaveSPARC.

Material Development

NREL has extensive experience in developing materials necessary for both FMDEC structures and embedded distributed energy converters. This experience, to name of few, leverages techniques ranging from upcycling of used polymers to the development of novel new elastomer electrodes.

Co-Design for Flexible Material Distributed Energy Converters

NREL is familiar with and has the experience necessary for the co-design of FMDEC technologies. Inherent to their nature, FMDECs require the co-design and concurrent engineering of, at minimum: (i) their flexible structures; (ii) their embedded distributed energy converters; and (iii) their active control power electronics.

Evaluation and Prototyping of Flexible Material Distributed Energy Converters

NREL has developed, and continues to develop, evaluation tools (e.g., technology performance level assessments) needed to characterize and assess FMDEC technologies—verifying through prototyping for an aim toward greater understanding and appreciation of the technology's optimal and realistic possibilities.

Technology Characteristics

This project has characterized and described archetypal features of FMDECs. The project also aims to investigate the probable cost and performance drivers associated with such archetypes. Thus far, FMDECs have been found to have:

  • Broad-banded wave energy absorptionarising mainly due to FMDECs many modes of motion
  • Robustness with intrinsic redundant energy converter systems—a result of multiple interlaced small power take-off units
  • Relatively low material procurement and assembly costs—predominant materials are polymers that are commonplace in terms of acquisition and roll-to-roll assembly practices
  • Simple deployment and survival mechanisms—most FMDECs archetypes can easily be rolled up, packaged, and stowed
  • Reduced maintenance schedules—inherent redundancy of distributed energy converters means the malfunction of one individual unit will likely not curtail overall device operation
  • Near-continuous structural control and adaptation—nearly every energy converter unit would be actively engaged via power electronic control systems and can act as either a generator (damping structural deformation), or an actuator (energizing structural deformation)
  • Unique and highly impactful opportunities for co-design of flexible structures with active control systems.

Challenges

Current challenges associated with the FMDEC technology domain centers upon the proper flexible material design for fatigue, optimal geometry composition, power conversion efficiencies, and energy converter unit design and embedment configurations.

With the broad scope of many design options—e.g., the application of co-design for development of FMDEC geometry, power take-off arrangements, and active control strategies—there are many reasons to be optimistic that currently identified FMDEC challenges can be resolved, at minimum, via clever concurrent design and development campaigns.

Publications

Internal Report on Evaluation of Cost and Performance Drivers: Key Cost and Performance Drivers Identified and Approximately Quantified, NREL Technical Report (2019)

Contacts

Blake Boren

RESEARCHER IV-MODEL ENGINEERING

Blake.Boren@nrel.gov

Jochem Weber

CHIEF ENGINEER

Jochem.Weber@nrel.gov