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Ocean Energy
Kim Cobbwith slides from Dr. Alam, MIT
Overview of Ocean Energy
-ocean energy is replenished by the sun and through tidal influences of the moon’s and sun’s gravitational forces
-near-surface winds induce wave action and cause wind-blown currents at about 3% of the wind speed
-tides cause strong currents into and out of coastal basins and rivers
-ocean surface heating by some 70% of the incoming sunlight adds to the surface water thermal energy, causing expansion and flow
-wind energy is stronger over the ocean due to less drag, although technically, only seabreezes are from ocean energy
How much energy and what types?-250 Billion barrels of oil worth of energy coming into ocean every day
-80 million barrels of oil per day produced
kinetic
potential
-250 Billion barrels of oil worth of energy coming into ocean every day
-80 million barrels of oil per day produced
How much energy and what types?
Theoretical global resource of ocean energy:
8,000-80,000 TWh/yr for wave energy800 TWh/yr for tidal current energy2,000 TWh/yr for salinity gradient energy10,000 TWh/yr for ocean thermal energy
World’s electricity consumption 17,000 TWh/yr
Source of Ocean Wave Energy
Wave Energy Extraction TechnologiesPoint Absorber(OPT,Finavera)
Oscillating Water Column (Energetech/Oceanlinx)
Attenuator, Pelamis WP Overtopping, Wave Dragon
Power From Ocean Waves
kW/m crest length
Power From Ocean Waves• Wave energy is strongest on the west coasts and increases toward the poles.• At approx. 30 kW/mcl in the Northwest (yearly avg.), a single meter (3.3 feet) of wave has the
raw energy to power about 23 homes.
Point absorber buoys: most common
Ocean Power Technology buoy, to best tested this month off Oregonwill power 50 homes. Federal permit obtained for grid-connection.
capacity = 150 kW
Oscillating Water Column Installations: LAND
NOTE: Plant Bowen (Georgia Power) operates at 3,200,000 kW
Oscillating Water Column Installations: OCEAN
“Overtopping” Wave Energy
Tidal Energy Conversion
Ocean Renewable Power Company installed first grid-connected tidal device in Cobbscook Bay, Maine in June, 2012. Powers 25 homes.
Ocean Thermal Energy Conversion
210 kW OTEC test plant, 1993-1998, Hawaii
Future OTEC plant: grow food and fuel?
Ocean Energy: Where are we today?
Wave Energy (grid-connected):-0.4MW and 0.5MW OWC off the coast of Pico and Islay by 2008-2.25MW Pelamis off Portugal by 2008-0.5MW section of Wave Star Energy off Denmark by 2009-7MW Wave Dragon off Wales by 2010
Tidal:- barriers: 240MW France in 1966 and 20MW in Canada-Current: 1.2MW off Ireland by 2009, 1MW France
Thermal:-0.2MW Hawaii 1993-1998
Ocean Energy: PROS and CONS?