mechanical and industrial engineeringwind energy center university of massachusetts retrospective:...

Mechanical and Industrial Engineering Wind Energy Center

University of Massachusetts

Retrospective: Preliminary Design and Permitting of the Hull Offshore Wind

Project

J. F. Manwell, Prof. and DirectorWind Energy Center

(a.k.a Renewable Energy Research Laboratory)

University of Massachusetts AmherstMay 12, 2011



Wind Energy in Hull

Pemberton/ Windmill Point (Hull Wind I)

Landfill (Hull Wind II)

Harding Ledge (Proposed Hull Offshore Wind)



The Proposed Hull Offshore Wind Project• Up to four wind turbines

3-5 MW (295’ - 417’ rotor diameter)• (Hull Wind 2: 1.8 MW, 262’ rotor)

• Installed in vicinity of Harding Ledge• 12 - 20 MW total generating capacity• Energy production (on average) could approach 100% of Hull’s electricity consumption



Offshore Wind Turbine and Support Structures

• Some offshore wind turbine support structure options

• Types suitable for Hull depend on seabed properties

s u b - s t r u c t u r e

p i l e

f o u n d a t i o n

p i l e

p l a t f o r m

t o w e r t o w e r

s u b - s t r u c t u r e

sea floor

s u p p o r t s t r u c t u r e

rotor-nacelle assembly

seabed

water level



Project History

• 2003: First conceived; modeled on Middelgrunden and Samsø (Denmark)– Based on one or more GE 3.6 MW turbines– First filing w/ Army Corps of Engineers

• 2006-8– Studies supported by MA Renewable Energy Trust– Wind/desalination study (Bureau of Reclamation)

• 2008: Certificate from MA EOEEA• 2009: Financial study by LaCapra



Preliminary Siting Constraints

• In Hull’s waters• Suitable for

commercial turbines – 20-40 ft deep

• Outside shipping lanes• We initially chose

these distances: > 1 mile from shore < 2 miles from proposed

connection point



Siting Criteria

• Minimize impacts– Marine environment – Human activities

• Fishing, boating, etc…• Ship and airplane traffic

• Transmission line – Allow a feasible landfall– Minimize length

• Maximize wind speeds• Minimize cost of energy



Wind Resource Assessment

• Used for:– Energy production estimates– Design of wind turbines and support structures

• Data from:– Monitoring on Little Brewster island and WBZ

towers– Historical data from Boston Harbor and offshore

buoys

• Mathematical projections



Wind Data Collection • Conventional anemometry and LIDAR



Wind Data Collection• Location and data collection:

Approx. 2 miles

Little Brewster Island

Aerial view of Little Brewster

Harding Ledge

Anemometer

LIDAR placed here



Wave/Current Data • Monitoring using a Sontek “acoustic Doppler profiler” (ADP) in vicinity of Harding Ledge• Correlations with offshore buoys

NDBC Data BuoySontek ADP



ADP Being Deployed



Sample Wave Data• Storm in mid-April, 2007:

54

52

50

48

46

44

42

40W

ate

r D

ept

h, F

t

10:34 PM4/17/07

10:35 PM 10:36 PM 10:37 PM 10:38 PM 10:39 PM

Date and Time

Wave Time Series Data

Web cam screen shot

www.northeastsurfing.comTypical waves during storm



Geophysical Studies

• Bathymetric data • Acoustic sub bottom profiles • Vibracore soil sampling• Sub bottom boring and sampling• Magnetic maps• Seafloor imaging



Area of Geophysical Study

• Off Nantasket Beach:Harding Ledge



Geophysical Data Collection

• Obtained with various instruments towed by or located on one or two boats



Bathymetric (Water Depth) Data• Obtained with echosounder

– SyQwest, Inc. HydroBox echosounder• Using 8-degree 200-kHz transducer



Bathymetry



Acoustic Sub-Bottom Profiling• Sound is produced by “boomer”, towed behind boat• Sound penetrates soil to various depths; some of it is returned• Return signal provides information about soil • Used to identify discontinuities in soil characteristics below ocean floor• Preliminary to soil borings



Sub-Bottom Profiling (Deep)

• Used Applied Acoustics Engineering CAT200 Boomer seismic system

Boomer emits sound at a peak frequency of 1125 Hz and a maximum power of 109.4 dB



Vibracore

• Vibracore: method of retrieving undisturbed core samples sub-bottom sediment

• Samples from relatively close to the sea bed

• Used here to study electrical cable path

http://www.americanvibracore.com/



Sub Bottom Soil Borings

• Obtain sub bottom soil samples to enable design of support structures

• Borings go through sediment into rock

• Typical depth ~50 ft

Drilling rig on jack-up barge off Nantasket Beach



Sample Soil Borings



Typical Soil Cross Section



Permitting• Environmental Notification Form (ENF) filed• Mass. permitting authority has issued certificate specifying certain actions required before final permit can be issued:



Permitting/Certificate Topics

• Project Description/Alternatives analysis• Permitting/Consistency• Green house gas reduction • Land alteration/Cumulative impacts• Fisheries/Marine resources/Wetlands/Water quality• Rare species/Avian/Bat impacts• Noise/Visual impacts• Historical/Archaeological• Construction/Maintenance/Decommissioning • Environmental monitoring



Alternatives Analysis

• Stay within town boundaries

• Limited space for land based turbines

• 1 nautical mile limit for viewshed concerns



Green House Gas Reduction Study

• Considered CO2, NOX and SO2

• Method used hour by hour simulation of the energy that would have been produced by the proposed offshore wind farm, resulting in decreased use of conventional power plant

• Turbines would result in GHG reductions greater than considering only average pollutants per kWh



Visual Impact: Photo Simulation (view from Clarion Hotel)



Magnetic Data Acquisition

• Magnetic data with using high resolution marine magnetometer system– Marine Magnetics, Inc. MiniExplorer

• For detecting metallic wrecks, ordnance, etc.

http://www.marinemagnetics.com/



Magnetometer Results• Some metal identified but nothing significant



Side Scan Sonar

• Sonar emits sound waves • Used for identifying underwater

surface features, shipwrecks, etc.• Device towed behind boat

http://www.accessnoaa.noaa.gov/nov02/developing.html



Side Scan Sonar Results• No significant artifacts found



Archaeological Studies

• Conclusion: – No evidence of Native American artifacts– No evidence of significant shipwrecks



Electrical/Cable Route Options

• Electrical study– 15 MW OK for grid as is

• Submarine cables transmit power to shore

• Layout needed for: – Cost estimates– Environmental impact

assessments– Interconnection planning Some possible cable routes



Support Structure/Foundation Study

• Undertaken by Grontmij Carl Bro (Denmark)• Focused on gravity structures• Suitable for hard soils• Could be fabricated locally



Typical Fabrication/Installation

Fabrication could be done at Quincy shipyard



Fisheries/Avian

• Some fisheries studies have been carried out, specifically regarding lobster

• More studies would be required• Avian studies remain to be done



Economics

• Capital cost estimates still uncertain, most recently estimated at approx. $60 million

• Capacity factors expected to be 30-35%• Wholesale cost (direct value) of electricity has

ranged significantly over last 10 years• Cost to produce electricity from offshore wind

turbines at present exceeds direct value• Multi-purpose project would be needed to

make economics work



Summary

• Many studies have been undertaken• No fatal flaws• Site still appears attractive for an offshore

wind energy project– Energy production, research and education

• More studies needed for permit• Detailed cost estimates not yet done• Feasible project plan remains to be developed



Electrical System

• Study showed local network could accept additional 14 MW of turbines

mechanical and industrial engineeringwind energy center university of massachusetts retrospective:...

Documents

director wind energy

hull offshore wind slide

cost of energy slide

wind speeds

capacity energy production

lidar slide

rotor diameter hull

lacapra slide