Overview of Wave Energy Conversion Technologies

Alex Ruane10/27/05

Tech Overview

• Wave Energy Basics

• Tapered Channel (TAPCHAN) Devices

• Floats or Pitching Devices

• Oscillating Water Column (OWC) Devices

AP Photo, NYC, 10/26/05

Wave Energy Basics

• Wave energy is derived from surface winds across entire ocean

• Mostly potential energy

• Waves lose energy as they are refracted by shallow ground and break

• Best sites for wave energy extraction need consistent waves– often near cliffs with deep bottom

Tapered Channel (TAPCHAN) Devices

• Waves are focused through an opening into elevated reservoir

• Potential energy gathered using proven hydro-electric technology

• Requires huge (8500 m2) collecting pool and wide entrance

from “Feasibility of Developing Wave Power as a Renewable Energy Resource for Hawaii”, Hawaii Department of Business, Economic Development, and Tourism

Floating or Pitching Devices

• Normally anchored to shoreline or seafloor

• Wave motion drives fluid through a pump or propels a turbine

– Energy may be extracted from both pitch and heave motions

• Normally Offshore Devices– sit in higher energy environment– requires connecting cables

Source: “Feasibility of Developing Wave Power as a Renewable Energy Resource for Hawaii”, Hawaii Department of Business, Economic Development, and Tourism

Oscillating Water Column (OWC) Devices

• Blow Hole as inspiration?

• Trapped air is expanded and compressed by changing wave level

– Propelled through air turbine• both directions of airflow generate energy

• Release valve helps prevent stalling

– maximum efficiency 0.7 - 0.8

Source: Falcao, 2004

Source: Clement et al., 2002