Distributed Embedded Energy Converter Technologies
NREL is building on an under explored area of research aimed at harvesting and converting ocean wave energy: distributed embedded energy converter technologies (DEEC-Tec).
The DEEC-Tec domain centers on combining many small energy converters into a single structure that harvests a much broader range of ocean wave energy than conventional approaches. One of the most innovative elements of DEEC-Tec is its ability to create flexible ocean wave energy converters, sometimes known as flexWECs. Such devices can stretch, twist, bend, expand, or undergo other structural deformations that, in turn, enable them to extract energy from the movement of ocean waves via numerous small distributed embedded energy converters.
DEEC-Tec-based devices (or flexWECs) do not have discrete joints or mechanical hinging mechanisms. The individual energy converters are simply very small transducers, which use dynamic structural deformation as their input and electricity, for example, as their output. These transducers can leverage any technique capable of damping or actuating motion within a DEEC-Tec structure. Dielectric elastomer generators, a type of transducer, are one such example.
By leveraging these features, DEEC-Tec structures can convert ocean wave energy into electricity throughout the structure. Wherever ocean energy causes dynamic deformation of the structure, energy conversion can occur directly in situ.
NREL actively develops and supports structured processes for innovating DEEC-Tec-based designs and aims to develop and deliver seedling concepts to the broader marine renewable energy community. See WaveSPARC.
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 DEEC-Tec Converters
NREL is familiar with and has the experience necessary for the co-design of DEEC-Tec-based ocean wave energy converters. Inherent in their nature, DEEC-Tec-based converters require the co-design and concurrent engineering of, at minimum: (1) their compliant structures’ forms, (2) their embedded distributed energy converters (the individual energy transducers), and (3) their active control power electronics systems and strategies.
Evaluating and Prototyping DEEC-Tec Converters
NREL has developed, and continues to develop, the evaluation tools (e.g., technology performance-level assessments and numerical modeling tools) needed to characterize and assess DEEC-Tec concepts, aiming toward a greater understanding and appreciation of the technology's optimal and realistic possibilities.
NREL has developed, and continues to develop, the evaluation tools (e.g., technology performance-level assessments and numerical modeling tools) needed to characterize and assess DEEC-Tec concepts, aiming toward a greater understanding and appreciation of the technology's optimal and realistic possibilities:
- Broad-banded ocean wave energy absorption: Many modes of motion make this absorption possible.
- Intrinsic redundant energy converter systems: Numerous interlaced small transducers (distributed embedded energy converters) provide mechanical redundancy and robustness (i.e., failure of some transducers need not mean failure of the overall flexWEC).
- Relatively low material procurement and assembly costs: Predominant materials are polymers that are commonplace and can be fabricated with well-established, roll-to-roll assembly practices, for example.
- Simple deployment and survival mechanisms: Most archetypes can easily be rolled-up, packaged, and stowed, when need be, for deployment and ocean storm avoidance.
- Reduced maintenance schedules: The distributed embedded energy converters within a DEEC-Tec structure can also act as sensors throughout that entire structure. The need for maintenance, therefore, can be handled in real time, based on the information those transducers are sending to monitors.
- Near-continuous structural control and adaptation: Actively engaging nearly every distributed embedded energy converter via power electronic control systems allowing them to act, therefore, as either a generator (damping structural deformation), or an actuator (energizing structural deformation), thereby enabling the alteration of a DEEC-Tec structure’s form in real time.
- Unique and highly impactful opportunities for co-design: For example, conceptualizing a DEEC-Tec structure’s form and flexible characteristics can occur directly alongside the development of the structure’s active control systems and manufacturing requirements.
Current challenges associated with the DEEC-Tec domain include proper material(s) design for fatigue minimization, optimal geometry composition, and power conversion efficiencies, as well as individual transducer unit design and embedment configurations.
With the broad scope of many design options (e.g., co-designing for the development of DEEC-Tec geometry, transducer arrangements, and active control strategies), there are many reasons to be optimistic about resolving the currently identified DEEC-Tec challenges.
Prototype and Codesign of Nascent Flexible Wave Energy Converter Concepts, NREL Presentation (2021)