Ocean Thermal Energy Conversion

Content

• Introduction

• Present Energy Resources

• Renewable Energy

• What is OTEC?

• Working Principe

• for besides produce electricity?

• Costs

• Projects

• Conclusion

Introduction

Energy is the raw material needed to fuel

any country’s economy growth. Advanced

economies have the capacity to develop

new sources of energy production or to

secure imports of foreign energy to meet

their needs.

Present EnergyResources

• Fossil fuels - coal, oil and natural gas.

• Nuclear fuels

• Difficult to estimate how long these fuels

will last - but is it sustainable

economically or environmentally?

Renewable Energy

Renewable Energy - Renewable energy is

natural energy which does not have a

limited supply. Renewable energy can be

used again and again, and will never run

out.

Sources of Renewable Energy

Renewable resources include solar energy,

falling water, wind, geothermal, waves and

temperature differences in the oceans

OTEC - Ocean Thermal Energy Conversion

The oceans cover a little more then 70

percent of the earth surface. This makes it

the world’s largest solar energy collector

and energy storage system.

1/10 of 1% of stored solar energy could

supply 20 times the amount of electricity

consumed in the USA on any given day

What is OTEC?

Ocean thermal energy conversion, or

OTEC, is a way to generate electricity using

the temperature difference of seawater at

different depths.

natural thermal gradient of the ocean

OTEC utilizes ∆ T

between warm

shallow and cold deep

ocean waters to run a

heat engine.

Global Ocean Thermal Gradient

WORKING PRINCIPLE

OTEC utilizes the ocean’s 20ºC natural

thermal gradient between the warm surface

water and the cold deep sea water(around

1 Km.) to drive a Rankine Cycle

Rankine cycle

How does OTEC work?

Cold Water Pipe Function:

• Bring up cold water

for OTEC cycle

• 4m diameter for the

10MW Pilot Plant

• 10m diameter for

100MW commercial

plant

• 1000m long

classification

Depending on the location

–Land based plant

–Floating plant

Depending on the cycle used

Open cycle

Closed cycle

Hybrid cycle

ELECTRICITY PRODUCTION

1. Closed cycle

• Ammonia can be used as a working fluid

2. Open cycle

• Water is the working fluid

• Desalinated water can be produced

3. Hybrid cycle

• Ammonia is the working fluid

• Warm sea water is flashed and is then used to vaporize ammonia

OTEC systems efficiency

• The OTEC systems efficiency is not quite

high because of the little temperature

difference used in the thermodynamic

cycles.

• Carnot Efficiency =𝑇1−𝑇2

𝑇1

SUMMARY

1. Based on Rankine cycle -

Thermodynamic cycle which converts

heat into work through a heat engine

2. As with any heat engine , the greatest

efficiency and power is produced with

the largest temperature differences.

3. Uses the vertical temperature gradient

in the ocean as a heat sink/source

What can you use OTEC for besides

produce electricity?

• Fresh Water

• Sea Food

• Air Conditioning

It is possible to use this resource to produce

fresh water instead of producing electric

power if there is a large ask for fresh water.

Fresh Water

The yield of fresh water from a 100-

megawatt power plant would be

approximately 33,000,000 cubic meter per

year, comparable to a flow of a medium-

sized river.

Sea Food

• OTEC plant it will stimulate the growth of

all kinds of seafood.

• The amount of food that can be produced

in this way is very large, larger in market

value than the electric power produced by

the plant.

Air conditioning and Refrigeration

Seawater air conditioning pumps cold

seawater (5oC) to a station via a deep-sea

pipeline to a cooling station, where it is

used to cool freshwater, which is then piped

to a building’s air conditioning system.

How much does an OTEC power plant cost?

The price of the first 10-megawatt plant is

$40,000,000; including development costs

and will produce profits of some

$10,000,000 per year, which means a

return of 25%.

So far, this concept of producing energy is

still experimental, although it is at least a

century old; created by the French engineer

Jacques D'Arsonval in 1881.

Mini OTEC (1979)

210 kW OC-OTEC Experimental Plant 1993

Conclusion:

• Though OTEC is clean and has great

potential, we have to make it more

efficient and cheap also.

• The main advantages of OTEC is that the

method is fuel free, can supply pure water

for both drinking and agriculture, can

supply refrigeration and cooling and can

provide a coastal community with reliable

energy.

Thank You