Cost-Benefit Analysis of a Hybrid Biophysical Approach to Wave Energy Extraction: Bio-Oscillator

Tabea Hildebrand,Richard Gorman,Christian Fischer,Craig Stevens,Veronica Relano

doi:10.3389/fmars.2021.628148

Abstract

A cost-benefit analysis (CBA) is described for a novel wave energy converters (WEC) design based on a marine hybrid bio-structure—a combination of macroalgae, shellfish or other species on a built frame. The Bio-Oscillator design utilises a hard “skeleton” (e.g., carbon fibre, wood) on which biological organisms (e.g., shellfish, large macroalgae) are grown. As waves pass by, the load generated by the oscillating drag and inertia is transferred through mooring lines to power takeoff technology. This novel approach essentially reverses the typical marine engineering view that “bio-fouling is bad” and instead leverages off the added-drag of biological growth on structures. The approach results in a structure that is largely biodegradable, naturally self-replicating and synergistic with the background environment, self-de-risking in terms of failure impact and can leverage off its own form to enhance energy capture beyond a conventional design. This reduces impact while connecting with conventional marine industries such as aquaculture. A CBA examines the economic pros and cons of this approach, focusing on installation and material costs, along with benefits from synergistic production. The analysis suggests that in addition to typical wave energy obstacles (e.g., cable length, capture width, and power take off) the benefits (biodegradability, harvestability, and carbon reduction) of replacing much of the mass of the structure with living biological material can be included.

Highlights

Sustainable, low carbon emission energy production remains the great challenge for our species
We examine the hypothesis described above with a costbenefit analysis (CBA) to explore key themes through high-level questions: (1) Does the cost-benefit analysis (CBA) suggest that a hybrid approach, such as the Bio-Oscillator, is viable? (2) Are there broader benefits from the nature of the approach? (3) What are the potentially socially sensitive components of such an approach? (4) while the present ideas focus on a regional application, how generalizable is the approach globally?
We extend this, based on Babarit’s (2015) database for capture-width ratio (CWR) of wave energy converters (WEC), an evaluation is made regarding the adaptation of the three device variations to the Bio-Oscillator concept

Summary

Introduction

Sustainable, low carbon emission energy production remains the great challenge for our species. With limited success in reduction of CO2 gases to date, a significant transformation in how the energy sector operates is required, if we are to avoid the more serious effects of the changing climate driven by greenhouse gas emissions (Gielen et al, 2019). Efforts to reduce the dependency on fossil fuels have seen an increased use of renewable energy over the last decades. While most technologies across the renewables sector have seen a significant growth in scale and economic viability over the last decades, marine renewable energy (other than off-shore wind) has generally lagged and presently plays little role in most countries’ strategies for energy independence (Gielen et al, 2019). Despite the evidence of technological viability, ocean power has increased by less than 1 TWh globally—a trajectory well short of the sustainable development scenario of 15 TWh by 2030 (IEA, 2019)

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