Energy from the Ocean

But first, more on energy storage:

Battery Farms:
• Acres of batteries; charged by transmission lines during periods of low demand
• Returned to transmission lines during periods of high demand
• Designed for load levelling
• One Acre could store about 400 MW-hours of energy and deliver 40MW of power (for 10 hours)

Ocean Power comes in 3 forms:

• Tidal Energy
• Current Flow Energy
• Heat Transfer Energy

The ocean is a huge reservoir for storing the energy of the sun that is incident on the earth. How huge is huge?

Incident flux on ocean surface area is 10^17 Watts or 0.1 Billion Billion Watts (its a large number)

The oceans are a huge heat engine. Temperature differences, caused by differences in insolation both in latitude and in depth.

• Equatorial waters warmer than higher latitude waters
• surface layers warmer than deeper layers
• This sets up an enormous circulation network
• 

Major currents are shaped by:

• Temperature differences (driven mostly by tilt of earth's axis)
• Prevailing wind patterns interacting with the surface waters (again driven mostly by tilt of earth's axis)
• the rotation of the earth --> the Coriolis Force
• shorelines of continental masses

Tapping the Current for Energy:

• Gulf current has 1000 times the flow of the Mississippi River(!)
• Current averages about 5 mph
• Density of water is higher as well
• Its always there - no intermittency problem --> no need for energy storage
• Build Turbines for underwater use
• Anchor a foundation to the ocean floor
• hundreds of miles long rigged with turbines
• cables on ocean floor to shore deliver the electricity

• An engineering challenge but there are few bad side effects from producing energy this way
• Obviously the capital costs are huge in this case but this does represent a Large Scale Solution

  More promising technology is OTEC (Ocean Thermal Energy Generation). This takes advantage of the fact that the ocean is an enormous heat engine.

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