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

-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 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

How much of earth does the ocean cover? 3/4 How much of the world’s energy consumption can be covered by wave energy? 50% How many barrels of oil worth of energy coming into ocean every day? 250 billion

Wave Energy Extraction Technologies Point 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.

What is an example of a heaving device? What is an example of an oscillating water column? A buoy A generator system

Point absorber buoys: most common

Ocean Power Technology Ocean Power Technology buoy, to best tested this month off Oregon will 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

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

Tidal Energy Conversion

Ocean Renewable Power Company installed first grid-connected tidal device in Cobbscook Bay, Maine in June, Powers 25 homes.

What is the device that the Ocean Renewable Power Company installed in 2012? Tidgen What is a pitching device? When ocean water moves the buoy platforms and creates energy.

Ocean Thermal Energy Conversion

210 kW OTEC test plant, , 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 MW Pelamis off Portugal by MW section of Wave Star Energy off Denmark by MW 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

Ocean Energy: PROS and CONS?