Feasibility of Offshore Wind Power in the South Atlantic Bight

Bill Bulpitt, Susan Stewart, Mary Hallisey HuntGeorgia Tech Strategic Energy Institute

Southeastern Energy SocietyNovember 20, 2006

Background• NSF Funded InfinitEnergy: A Coastal Georgia

Partnership for Innovation – Search for alternative energy options to stimulate

economic opportunities for Coastal Georgia region.• Strategic energy technology assessments • Determine potential for implementation

• Initial assessments of offshore wind potential in coastal Georgia merited further study

• Approached local utility to perform a detailed conceptual design study for an offshore wind farm

South Atlantic Bight Wind Resource

• Bight definition:– Long gradual bend or recess in

coastline forming large open bay.– Describes coastal ocean between

South Carolina and Florida.

• 140 km wide continental shelf• Off of Georgia’s coast alone:

– < 20m deep: ~8,000 sq.km– < 30m deep: ~12,800 sq.km

South Atlantic Bight Wind Resource

(continued)

• Rare offshore wind data available:– 50 m high anemometer– Online since June 1999 (nearly 7 years)– 27 m deep water, 60 km offshore– 6-minute data averages

Grays Reef Buoy

R2 Tower

Savannah Light Tower

R2 Tower Annual Average Wind Speeds

7.13

6.95

7.10

7.37

7.72 7.69

6.5

7.0

7.5

8.0

8.5

1999 2000 2001 2002 2003 2004 2005 2006Year

Av

era

ge

An

nu

al

Win

d S

pe

ed

(m

/s)

R2 Tower @ 50m

Overall Annual Average, 7.36 m/s

Average Annual Wind Speed Comparisons at 50 m

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1985 1990 1995 2000 2005

Year

Ave

rag

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ua

l Win

d S

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(m

/s)

Savannah Light Tower @ 50m

Gray's Reef Buoy @ 50m

R2 Tower @ 50m

R2 Tower Monthly Average Wind Power Density (W/m2)

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200

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1 2 3 4 5 6 7 8 9 10 11 12

Month

6 Y

ear

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/m^

2) a

t 5

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Class: 7

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1

2

Wind Farm Conceptual Design Study

• Working with Southern Company on a detailed feasibility study of an offshore wind farm in Coastal Georgia.

• Teams incorporating both entities working on project tasks.

• Interaction with State, DOE,MMS, turbine vendors, and environmental organizations throughout study

Update on Project Tasks

• Wind Turbine Technology Review

• Turbine Foundation and Platform Options

• Selection of Offshore Sites/Interconnection Points

• Submarine Cabling Requirements

• South Atlantic Bight Benefits & Concerns– Environmental and other issues

Wind Turbine Technology

• 3 major offshore wind turbine vendors– Others have not “weatherized” products for

this environment.– Visited vendors’ projects in Europe

• Discussions with vendor sales reps

Arklow

Arklow

Project Statistics• Turbines 3.6MW x 7• Dept of piles 35-45m• Weight of piles 280tonne (5m diameter)• Weight of turbines 290tonne• Blades 50.5m, 15tonne each• Nacelle/Hub height 73.5M• Rotational speed 8.5 – 15 rpm• Distance offshore 10km• Onshore cable 5km• Voltage 38kV distribution connected• Rotor diameter 104m > soccer pitch area• 25MW serves 16,000 households (Irish)

• Sandbank 24 miles long & 2.5 wide, depths 3 -20 m• Largest commercially operating turbines installed to date• Largest consented offshore site todate

Source: McAdam

Scroby Sands

Scroby Sands

Country: United KingdomLocation: East Anglian Coast, 3km east of Great YarmouthTotal Capacity: 60 MWNumber of Turbines: 30Distance to Shore: 2.5 kmDepth: 4-8 mCapital Costs: about 110 million EuroStatus: BuiltConstruction Date: 2003Manufacturer: VestasTotal Capacity: 2 MWTurbine-type: V80 - 80m diameter/ 60m hubheightMean Windspeed: 7.5 m/s Windfarm Developer: E.ON UK

Horns Rev

Horns RevCountry: DenmarkLocation: West CoastTotal Capacity: 160 MWNumber of Turbines: 80Distance to Shore: 14-20 kmDepth: 6-12 mCapital Costs: 270 million EuroStatus: Operational Construction Date: 2002 Manufacturer: VestasTotal Capacity: 2 MWTurbine-type: V80 - 80m diameter / 70m hubheightMean Windspeed: 9.7 m/sAnnual Energy output: 600 GWhWindfarm Developer: Elsam http://www.hornsrev.dk/Engelsk/default_ie.htm

Wind Turbine Technology(continued)

• Sellers Market– Demand for turbines high in Europe & Asia due to

Kyoto Protocol and other promotional programs.– May be hard to obtain equipment for use in U.S.

before 2008-2009.– Cost information difficult to acquire from vendors

• They require a review in great detail of wind farm potential

• PTC “on again – off again” history not helpful.

Wind Turbine Technology(continued)

• Selection of a unit depends on best economics (power output for the cost) for the given wind resource.– Power output calculated from vendor power

curves using R2 data extrapolated to 80 m.

Annual Capacity Factor Using Three Different Wind Turbines

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

1998 2000 2002 2004 2006

Year

Cap

acity

Fac

tor

Turbine A, 3.6 MWTurbine B, 2.3 MWTurbine C, 2.0 MW

Turbine Foundation and Platform Options

• From site visits, monopile support preferable– Steel tube 4-5 m diameter driven 15-30 m into ocean floor– Water depth < 20 m

• Most expertise resides in Europe, as does the necessary equipment

• R2 Tower wave characteristics:– Significant wave height = 1.16 m– Maximum wave height = 6.3 m

Selection of Offshore Sites Interconnection Points

• Geographical consistency of wind resource• Substation/landfall considerations:

– Grid interconnection access points• Proximity to coast• Operating voltage• Expansion availability• Accessibility to beach for access

– Shipping lanes– Cabling distance to shore– Cable landfall environmental impact

Economics

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2.0% 4.0% 6.0% 8.0% 10.0% 12.0% 14.0% 16.0% 18.0%

Interest Rate (%)

Cen

ts/k

Wh

50 MW Farm

100 MW Farm

160 MW Farm

20 Year Amoritization, Cost includes 1.9 cents/kWh O&M and PTC

Coal

Natural Gas Simple Cycle

Natural Gas Combined Cycle

Submarine Cabling Requirements • Trench for cable:

– Prepared with water jet• Sand settles over top after cable is laid

– Depth of trench important to prevent damage from anchors and trawlers

• Georgia specific:– Submerged barrier islands– Sand filled channels (former rivers)– Shifting sands

South Atlantic BightBenefits & Concerns

• Many benefits and concerns are more specific to South Atlantic Bight Region:– Environmental Issues

• Migratory pathways and habitats for– Avian species– Right whales ( critical habitat – only known calving

ground)– Sea turtles

South Atlantic Bight Benefits & Concerns

(continued)– (cont.) Environmental Issues

• Warm weather– Lightning strikes– Hurricanes

» Technology developments » Statistical studies

South Atlantic Bight Benefits & Concerns

(continued)

– (cont.) Environmental Issues• Fisheries

– May create an area closed to fishing– Could help increase fish populations

• Hard bottom substrates– Could be extended via wind farm foundations and scour

protection» Creating larger habitat for existing species.

South Atlantic Bight Benefits & Concerns

(continued)

– Other Issues• Coexistence with military installations• Hydrography and coastal effects

– Submerged barrier islands

• Community acceptance• SocioEconomics • Viewshed

– Unpopulated stretches of coastline

Bringing ‘Offshore’ Wind Energy into the Mainstream

• Need a pathway for development– Will vary by region due to different:

• Wind Resources• Geography• Environmental Issues• Permitting Issues• Coastal population density