Ocean Energy Kim Cobb with slides from Dr

Ocean Energy Kim Cobb with slides from Dr. Alam, MIT

Estimates of 21 st Century World Energy Supplies YEAR Edwards 2001 A barrel (42 U. S. gallons) of crude oil = 5. 8 × 10^6 BTU = = 6000 MJ or about 1. 70 MWh.

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

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

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 Theoretical global resource of ocean energy: 8, 000 -80, 000 TWh/yr for wave energy 800 TWh/yr for tidal current energy 2, 000 TWh/yr for salinity gradient energy 10, 000 TWh/yr for ocean thermal energy World’s electricity consumption 17, 000 TWh/yr

Source of Ocean Wave Energy

Wave Energy Extraction Technologies Point Absorber (OPT, Finavera) Attenuator, Pelamis WP Oscillating Water Column (Energetech/Oceanlinx) Overtopping, Wave Dragon

Power From Ocean Waves k. W/m crest length

Power From Ocean Waves • • Wave energy is strongest on the west coasts and increases toward the poles. At approx. 30 k. W/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

Oscillating Water Column Installations: LAND NOTE: Plant Bowen (Georgia Power) operates at 3, 200, 000 k. W

Oscillating Water Column Installations: OCEAN

“Overtopping” Wave Energy

“Sea Snake” Wave Energy 121 m long, 3. 5 m tall!

Tidal Energy Conversion

Ocean Thermal Energy Conversion

210 k. W OTEC test plant, 1993 -1998, Hawaii

Future OTEC plant: grow food and fuel?

Ocean Energy: Where are we today? Wave Energy (grid-connected): -0. 4 MW and 0. 5 MW OWC off the coast of Pico and Islay by 2008 -2. 25 MW Pelamis off Portugal by 2008 -0. 5 MW section of Wave Star Energy off Denmark by 2009 -7 MW Wave Dragon off Wales by 2010 Tidal: - barriers: 240 MW France in 1966 and 20 MW in Canada -Current: 1. 2 MW off Ireland by 2009, 1 MW France Thermal: -0. 2 MW Hawaii 1993 -1998

Ocean Energy: PROS and CONS?