Wave Energy Technology

Why explore wave power in Hawai‘i? Wave Energy Levels (kW/m of Wave Front) Formula used to calculate this Power (in kW/m) = k H ² T ~ 0.5 H ² T k = constant, H = wave height (crest to trough) in meters, and T = wave period (crest to crest) in seconds Wave Energy Levels (kW/m of Wave Front) Formula used to calculate this Power (in kW/m) = k H ² T ~ 0.5 H ² T k = constant, H = wave height (crest to trough) in meters, and T = wave period (crest to crest) in seconds

Overview G What is wave power? G Wave energy conversion systems (WECS) G Types of energy G Physics of water power G Benefits & Challenges G Wave Energy Technology (WET) in Hawai‘i G What is wave power? G Wave energy conversion systems (WECS) G Types of energy G Physics of water power G Benefits & Challenges G Wave Energy Technology (WET) in Hawai‘i PowerBuoy 

What is Wave Power? Wave power is the ________ of ocean surface waves and the capture of that energy to do useful _______ - including electricity generation, desalination and the pumping of water. Wave power is a form of __________ energy. Tidal power and ocean currents are other sources of ocean hydro-electric power. Wave power is the ________ of ocean surface waves and the capture of that energy to do useful _______ - including electricity generation, desalination and the pumping of water. Wave power is a form of __________ energy. Tidal power and ocean currents are other sources of ocean hydro-electric power. energy work renewable

Wave Energy Conversion Systems (WECS) 1. Oscillating Water Columns (OWC) - generate electricity from the wave-driven rise and fall of water in a cylindrical shaft. The rising and falling water column drives air into and out of the top of the shaft, powering an air- driven turbine. 1. Oscillating Water Columns (OWC) - generate electricity from the wave-driven rise and fall of water in a cylindrical shaft. The rising and falling water column drives air into and out of the top of the shaft, powering an air- driven turbine.

Wave Energy Conversion Systems (WECS) 2. Wave Surge or Focusing Devices - These shoreline devices, also called "tapered channel" or "TAPCHAN" systems, rely on a shore- mounted structure to channel and concentrate the waves, driving them into an elevated reservoir. Water flow out of this reservoir is used to generate electricity, using standard hydropower technologies. 2. Wave Surge or Focusing Devices - These shoreline devices, also called "tapered channel" or "TAPCHAN" systems, rely on a shore- mounted structure to channel and concentrate the waves, driving them into an elevated reservoir. Water flow out of this reservoir is used to generate electricity, using standard hydropower technologies.

Wave Energy Conversion Systems (WECS) 3. Floats or Pitching Devices - These devices generate electricity from the bobbing or pitching action of a floating object. The object can be mounted to a floating raft or to a device fixed on the ocean floor. Archimedes Wave Swing

Which is it? 1. Oscillating Water column? 2.Wave Surge/Focuser? 3. Float/Pitch Device?

Wavegen  created the “ Limpet ” … the world ’ s 1st wave power station. It is in Islay, Scotland.

Which system are these devices? WaveRoller Pelamis

Salter Duck WaveDragon None of the above!

The Physics of Hydro-Electric Power Key physics concepts: energy, power & work What is Bernoulli’s Principle? (hint: think about conservation of energy) How might engineers apply it to wave energy? Key physics concepts: energy, power & work What is Bernoulli’s Principle? (hint: think about conservation of energy) How might engineers apply it to wave energy?

Types of energy in a fixed wave power generator Where in this diagram do each of the following energy types occur?  G wave energy   mechanical energy   pneumatic energy   electrical energy Where in this diagram do each of the following energy types occur?  G wave energy   mechanical energy   pneumatic energy   electrical energy

Wave Power: Benefit or Challenge? G Portable, modular design G Noise G Pollution G Cost-saving potential G Maintenance G Site specifications G Portable, modular design G Noise G Pollution G Cost-saving potential G Maintenance G Site specifications G Abundance of resource G Appearance of device G Marine life effects G Fishing & recreation G Installation & development cost G Coastal erosion G Sustainability

Hawaii’s PowerBuoy ™ Cylindrical, Steel Buoy Diameter to 5 meters. Length – 12 to 20 meters. Mass – 35 to 55 tons. Operates meters below surface. Average System Output: 20 kW Peak Output: kW Mooring: Rigid spar buoy with universal joint at base. Deadweight anchor rock bolted into the substrate provides up to 100-ton holding force. Cylindrical, Steel Buoy Diameter to 5 meters. Length – 12 to 20 meters. Mass – 35 to 55 tons. Operates meters below surface. Average System Output: 20 kW Peak Output: kW Mooring: Rigid spar buoy with universal joint at base. Deadweight anchor rock bolted into the substrate provides up to 100-ton holding force.

Kane‘ohe Marine Corps Base WET Project G The PowerBuoy  is low-cost, efficient, and readily deployable electric power that can reduce costs at Kane‘ohe Marine Corps Base & similar naval sites Subsea cable installation

Issues KMCB had to address G Shoreline Conditions G Oceanographic Conditions G Infrastructure Impacts G Recreation Impacts G Public Safety G Cultural considerations G Shoreline Conditions G Oceanographic Conditions G Infrastructure Impacts G Recreation Impacts G Public Safety G Cultural considerations Subsea Cable Installation

Possible Environmental Issues G Alien Invasive Species G Entanglement G Entrapment G Electromagnetic Radiation (EMR) G Electrical leakage G Heat generation and release G Noise G Alien Invasive Species G Entanglement G Entrapment G Electromagnetic Radiation (EMR) G Electrical leakage G Heat generation and release G Noise Diver Working on Plate Installation for Biological Monitoring

Hawaiian Blessing of SiteCable and Vault Located Above Ground G Historic Preservation G structure eligible for listing in National Register of Historic Places G Cultural Consideration G Ancient Hawaiian Burial Ground

Researchers found Environmental Advantages G No fuel G Absence of CO 2 emissions, radiation, and particulate matter G No waste or disposal requirements G No danger of spillage or other environmental damage G No negative impact on marine life G can encourage growth G Live coral areas avoided G Minimal aesthetic impact G No noise pollution G No visual pollution G No fuel G Absence of CO 2 emissions, radiation, and particulate matter G No waste or disposal requirements G No danger of spillage or other environmental damage G No negative impact on marine life G can encourage growth G Live coral areas avoided G Minimal aesthetic impact G No noise pollution G No visual pollution Anchor Box

Goals of WET in Hawai‘i G Develop and Validate Technology G Demonstrate reliability and cost effectiveness G Demonstrate feasibility of combining power from a multi-buoy array Anchor Installation