How OTEC Works

by Keith Bishop

In talking to some folks yesterday I was amazed at the misconceptions surrounding OTEC – so I put this together for them.

OTEC (Ocean Thermal Energy Conversion) is an technology that has long been considered a potential source of low-cost, carbon-neutral, base-load electricity as well as bulk desalinated water. While the technology has been under development for over 60 years, commercialization has not yet been realized.

As the global price of energy increases in step with concern for reducing greenhouse emissions, a valuable opportunity presents itself for us to take the lead in forming an international consortium to complete the excellent work begun by OTEC researchers and developers worldwide.

The Bahamas is considered a potential base for OTEC due to the close proximity to land of deep, cold ocean water An assessment of the potential opportunities associated with offshore OTEC plants might include:

∑ Low cost air-conditioning
∑ Low cost power production
∑ Production of bulk fresh water
∑ Aquaculture and mariculture
∑ Nutraceuticals, pharmaceuticals.
∑ Salt, brine
∑ Marine adventure tourism

Ocean thermal energy conversion is a way to generate electricity using the temperature difference of seawater at different depths. Nearly all energy utilized by humans originates from a cyclic heat engine. A heat engine is placed between a high temperature reservoir and a low temperature reservoir. As heat flows from one to the other, the engine extracts some of the heat in the form of work.

OTEC is a means of converting into useful energy the temperature difference between surface water of the oceans in tropical and sub-tropical areas, and water at a depth of approximately 1 000 meters, which comes from the polar regions.

OTEC is perhaps the most exciting world energy resource for the future (the near future). It promises vast amounts of energy (even ten times the current worldwide human utilization) that is cheap (competitive with $25-per-barrel crude oil), naturally self-renewing, and ecologically friendly.

The oceans cover a little more than 70 per cent of the Earth's surface. This makes them the world's largest solar energy collector and energy storage system. On an average day, 60 million square kilometers (23 million square miles) of tropical seas absorb an amount of solar radiation equal in heat content to about 250 billion barrels of oil.

The ecological impacts of OTEC plants would need to be thoroughly considered given the sensitivity of Bahamian marine resources. Here are some preliminary considerations. The flow of water from a 100-megawatt OTEC plant would equal that of a large river. Since the salinity of the ocean is nearly uniform, these large discharges will not significantly affect the salinity of the receiving waters.

The temperatures of the seawater discharges could be significantly above their initial temperatures. If the warm and cold discharges were mixed, they could have a temperature that could be discharged at a depth below the bottom of the surface layer in order to avoid contaminating the surface water intake.

At a depth somewhere below 100 m, the discharge will be denser than the water at that depth and will disperse gradually downward, having little impact on the surface layer where most life exists.

February 29, 2008 | Permalink

Ocean thermal energy conversion is a way to generate electricity using the temperature difference of seawater at different depths. Nearly all energy utilized by humans originates from a cyclic heat engine. A heat engine is placed between a high temperature reservoir and a low temperature reservoir. As heat flows from one to the other, the engine extracts some of the heat in the form of work.

OTEC is a means of converting into useful energy the temperature difference between surface water of the oceans in tropical and sub-tropical areas, and water at a depth of approximately 1 000 meters, which comes from the polar regions.

OTEC is perhaps the most exciting world energy resource for the future (the near future). It promises vast amounts of energy (even ten times the current worldwide human utilization) that is cheap (competitive with $25-per-barrel crude oil), naturally self-renewing, and ecologically friendly.

The oceans cover a little more than 70 per cent of the Earth's surface. This makes them the world's largest solar energy collector and energy storage system. On an average day, 60 million square kilometers (23 million square miles) of tropical seas absorb an amount of solar radiation equal in heat content to about 250 billion barrels of oil.

The ecological impacts of OTEC plants would need to be thoroughly considered given the sensitivity of Bahamian marine resources. Here are some preliminary considerations. The flow of water from a 100-megawatt OTEC plant would equal that of a large river. Since the salinity of the ocean is nearly uniform, these large discharges will not significantly affect the salinity of the receiving waters.

The temperatures of the seawater discharges could be significantly above their initial temperatures. If the warm and cold discharges were mixed, they could have a temperature that could be discharged at a depth below the bottom of the surface layer in order to avoid contaminating the surface water intake.

At a depth somewhere below 100 m, the discharge will be denser than the water at that depth and will disperse gradually downward, having little impact on the surface layer where most life exists.

Comments

[Name]

I'd like to know what their misconceptions were.