Ocean Energy Kim Cobb with 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

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) Oscillating Water Column (Energetech/Oceanlinx) Overtopping, Wave Dragon Attenuator, Pelamis WP EPRI surveyed, collected information and assessed existing wave energy conversion devices. Sixteen worldwide manufacturers were queried of which 12 provided information of which eight devices passed the initial screening consisting of two factors Is the device likely to be ready for demonstration in the late 2006 time period? Has the device manufacturer provided sufficient information to prove the survivability in storm conditions? The eight devices which passed the initial screen can be grouped into one of four generic types as shown above AquaEnergy floating point absorber Ocean Power Delivery Pelamis floating attenuator – the most technologically mature of the devices. A full scale prototype achieved the milestone last summer of being the first offshore wave device to transmit power to an electrical grid Wave Dragon floating overtopping ramp terminator Energetech bottom mounted oscillating water column terminator

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

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

Oscillating Water Column Installations: OCEAN

“Overtopping” Wave Energy

“Sea Snake” Wave Energy 121m long, 3.5m tall!

Tidal Energy Conversion

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?