Walker Carr, Joseph Cognato, Kashief Moody, Ashley Saunders

busyicicleMechanics

Feb 22, 2014 (3 years and 1 month ago)

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Walker Carr, Joseph
Cognato
,
Kashief

Moody,
Ashley Saunders

1


Ocean covers a little more than 70% of Earth’s
surface


World’s largest solar energy collector and storage
system


On average, 23 million square miles of tropical seas
absorb an equivalent of 250 billion bbl in solar
radiation.


-
if less than even 1/10 of
1% of
this energy were
converted into electric power, it would supply more
than 20 times the amount of electricity consumed in
the US in one
day


OTEC
-

technology that converts solar
radiation into electrical power




2


First credit received for the ideation of electricity
production by using surface and deep ocean water was in
1869


Jules Verne, author of “Twenty Thousand Leagues Under the Sea”



OTEC technology was again proposed in 1881


French physicist, Jacques
Arsene

d’Arsonval

proposed to tap the
thermal energy of the ocean



First OTEC plant built in 1930


Georges Claude, a student of Jacques, built the first OTEC plant in
Cuba


Georges built a second plant aboard a cargo vessel which was
moored off of Brazil’s coast



The United States was first involved in OTEC in 1974


Established the Natural Energy Laboratory of Hawaii Authority

3


Location restrictions:


The temperature difference between warm and cold waters is 20
°
C for significant
power production


Underwater seafloor elevation


restricts the number of desirable sites along the shoreline of major continents


Logistics


Socioeconomic factors


Political factors


Best land based locations are on islands



4

5


Locations

of facilities can range:


On land or near shore facilities


Shelf
-
mounted

facilities


Free
-
floating facilities



6


On Land:


offers greater protection from storms and
violent water


requires a longer cold
-
water intake pipe


On shore:


reduces the length of the cold
-
water intake
pipe


prone to damage by storms and seas



Overall Advantages:


Doesn’t have to be moored


Doesn’t require lengthy power cables


Less maintenance required than shelf
mounted or free floating facilities


Resources are more easily accessible



Overall Disadvantage:


Proximity to surf zone means dealing with its
turbulent waves




7


These facilities are built in shipyards,
towed to their desired locations and
then are fixed to the seafloor bottom



Advantages:


No longer in range of surf zone’s
turbulent effects


Closer proximity to cold
-
water resources


Disadvantages:


Still prone to open water effects


Although closer to cold
-
water resources,
this means more challenges in delivery


Generally, more costly

8


Advantage:


Cold water pipe can descend directly down



Disadvantages:


Difficult to stabilize


Attached cables are more prone to damage


Depths greater than 1000m make maintenance and
repair difficult

9


Steel and titanium construction of piping,
pump facilities, and heat exchangers drives
high cost.



Aluminum heat exchangers have been developed to
replace conventional steel designs.



Fiberglass piping designed by both Lockheed
Martin and Sea Solar Power for easy onsite
production.

10


Utilizes warm (surface) water to make electricity


It is put into a low pressure container where it boils


Expanding water vapor is used to drive a low
-
pressure turbine


Salt of the water remains in the low pressure container


Turbine is attached to an electrical generator


Cold sea water is then used to condense the steam back into a
liquid


The air that is released from the water (incondensable) are then
compressed to a pressure necessary to remove it from the system

11


Evaporator, turbine and condenser are in a
partial vacuum


Reduced pressures here range from 1
-
3% of the
atmospheric pressure


The low pressure steam has a high specific volume


The steam velocities must remain low


The components must have large flow areas to ensure this

12


Can be modeled as a saturated
Rankine

Cycle


Unlike open
-
cycle systems, which use warm water to make electricity,
closed
-
cycle systems utilize ammonia


Ammonia is attractive for its low boiling point


Other fluids with similarly low boiling points can be used as well


Warm (surface) water is pumped through a heat exchanger


Here, the ammonia is vaporized


Expanding vapor is then used to turn a turbo
-
generator


Cold (deep) water is then pumped into the system


This water is used to condense the vapor back into a liquid to be recycled

13


First at
-
sea OTEC system to produce more
power than it consumed was from closed
-
cycle OTEC


1979 the Natural Energy Laboratory along with
private
-
sector partners developed the experiment


The vessel was moored 1.5 miles off of Hawaii’s
coast


Produced enough electricity to provide a net energy
output

14

15


Pros:


OTEC serves as an alternative to petroleum plants


Extraction of gases trapped in the ocean water


Hydrogen, methanol, ammonia, chlorine


Air conditioning


Can save $200k
-
$400k/year


Non
-
polluting


Consistent power generation


Cold water from pipes can chill fresh water on coast


Leads to new agricultural life


16


Expensive


Capital intensive


Generating 10 million MW
of OTEC power would lead
to cooling the surface
temperature of the ocean
by 1
°
C


Low efficiency


Only 2
-
2.5% electrical
efficiency


Biofouling


17


Conventional Power Sources burn fossil fuels
as a means to generate electrical power


Coal
-
fired Power Plants


Natural Gas Power plants


Petroleum Power plants


Fossil fuels currently account for 70% of
electricity generated in the U.S.


67% worldwide



18


Rank

State

Coal

Pet.

Nat. Gas

Other
Gases

Nuclear

Hydro

Pumped
Storage

Geo.

Wood

Other
Biomass

Solar

Wind

Other

Total

1

Texas

150,173

708

186,882

3,291

41,335

1,262

--

--

900

545

8

26,251

339

411,695

2

Pennsylvania

110,369

571

33,718

552

77,828

2,332

-
708

--

675

1,708

8

1,854

845

229,752

3

Florida

59,897

9,122

128,634

8

23,936

177

--

--

2,019

2,387

80

--

2,834

229,096

4

California

2,100

1,059

107,522

1,695

32,201

33,431

-
171

12,600

3,551

2,451

769

6,079

839

204,126

5

Illinois

93,611

110

5,724

161

96,190

119

--

--

0

670

14

4,454

300

201,352

6

Alabama

63,050

200

39,235

277

37,941

8,704

--

--

2,365

12

--

--

366

152,151

7

Ohio

117,828

1,442

7,128

254

15,805

429

--

--

399

276

13

13

12

143,598

8

Georgia

73,298

641

23,884

--

33,512

3,322

-
278

--

3,054

127

--

--

18

137,577

9

New York

13,583

2,005

48,916

--

41,870

25,472

-
529

--

547

1,671

--

2,596

832

136,962

10

North
Carolina

71,951

293

8,447

--

40,740

4,757

--

--

1,876

195

11

--

407

128,678



U.S. Total

1,847,290

37,061

987,697

11,313

806,968

260,203

-
5,501

15,219

37,172

18,917

1,212

94,652

12,855

4,125,060

19


Conventional power plants are large
contributors to environmental destruction in
the form of


Air pollution


Water and land pollution


Thermal pollution

20


Important air pollutants produced by fossil fuel
combustion include


Carbon dioxide


Nitrogen oxide


Carbon monoxide


Sulfur oxide


hydrocarbons


The most important of the pollutants is CO
2


Its percentage in the atmosphere has increased by 25% in
the last 150 years


Continued increases quantities within the atmosphere will
lead to higher average temperatures on a global scale


21


Pollutant

Hard coal

Brown
coal

Fuel oil

Other oil

Gas

CO
2

(g/GJ)

94600

101000

77400

74100

56100

SO
2

(g/GJ)

765

1361

1350

228

0.68

NO
x

(g/GJ)

292

183

195

129

93.3

CO (g/GJ)

89.1

89.1

15.7

15.7

14.5

22


The combustion of coal is responsible for the
largest environmental impact


There are about 600 functioning coal
-
fired
plants in the U.S.


Accounts for 50% of electricity generated in the U.S.


50,000 worldwide accounting for 44% of electricity
generated




23


Waste and air pollution is generated by the
tons


more than 75% of this waste is disposed of in onsite
unlined, landfills and surface impoundments.


Toxic substances in the waste includes


Arsenic


mercury


Chromium


Cadmium



24


Pollution produced by an 500 MW coal
-
fired
power plant annually

Pollutant

Carbon

Dioxide

Sulfur

Dioxide

Nitrogen
Oxide

Carbon

Monoxide

Mercury

Lead

Arsenic

Amount

3,700,00
0 tons

10,000
tons

10,200
tons

720 tons

170 lb

114
lb

225 lb

25


Prototype facilities and research were kick
started in mid 1970s during oil crisis.



Lockheed Martin, Saga University of Japan, The Natural
Energy Laboratory of Hawaii Authority (NELHA), and various
small contractors started.


First focus on biofouling, heat exchangers, and piping
facilities.


Various size facilities ranging from 1kW to 210kW





26


Lockheed, funded with $12M started the
design of a new 10MW facility with
Makai

engineering at
Kahe

Point, Hawaii.

27


Integration planned with air conditioning of
cities in Hawaii.



Cold water from OTEC plant is piped into the
city where it joins with current chilled water
facilities for major architecture.



Honolulu Seawater Air Conditioning first
group to start under clean energy initiative.

28


Saga University has developed and tested the
new
Uehara

cycle for OTEC facilities.

29


Future plants


Sea Solar Power currently building 25MW plant,
future plans to build 100MW plant.


Mobile ‘grazing’ floating facilities


Competing with solar and wind power in
isolated areas


Hawaii aims to achieve 70% “clean” energy by
2030


40% of which would come from renewable
resources

30


http://www.otecnews.org/otec
-
articles/ocean
-
thermal
-
energy
-
conversion
-
otec
-
by
-
l
-
a
-
vega
-
ph
-
d/#open


http://www.nrel.gov/otec/


http://www.answers.com/topic/ocean
-
thermal
-
energy
-
conversion


http://www.energysavers.gov/renewable_energy/ocean/index.cfm/myto
pic=50010


http://www.eurocean.org/np4/124.html


http://knol.google.com/k/ocean
-
thermal
-
energy
-
conversion#


http://www.britannica.com/EBchecked/topic/424415/ocean
-
thermal
-
energy
-
conversion
-
OTEC


http://cogeneration.net/ocean
-
thermal
-
energy
-
conversion/


http://www.otecnews.org/


http://www.engineeringtoolbox.com/specific
-
heat
-
fluids
-
d_151.html


http://www.nodc.noaa.gov/dsdt/cwtg/hawaii.html


http://www.theengineer.co.uk/in
-
depth/tropical
-
idea
-
ocean
-
thermal
-
energy
-
conversion/1008208.article


http://www.otec.ws/




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