Wave Energy Conversion Potential off New York and New Jersey

Presenter: Michael Raftery, M.E.

Research Engineer

Stevens Institute of Technology

Office: +1 201 216 8704

Testing and Research Funded by

The Office of Naval Research

Agenda

• Wave Energy Conversion Challenges

• Developing Solutions

• Wave Tuning Research Results

• Wave Energy Harnessing Device

• Power Take-Off System

• Northeast Wave Energy Region

• Performance Projections 1:10 Scale to Prototype

• Load Control-Energy Storage

• Southern New Jersey

• Business Case Executive Summary

Wave Energy Conversion Challenges

• Mild wave slopes do not provide sufficient acceleration of power take-off components for existing systems to operate efficiently

• Buoyancy and stability related catastrophic failures have occurred during prototype deployments

• Power take-off and electricity generation are strongly coupled in existing systems

• Storm events result in extreme structural loads in all wave climates

Developing Solutions

• Capable of tuning waves and concentrating wave power

• Capable of eliminating single-point, buoyancy and stability related failures

• Capable of decoupling power take-off from electricity generation with energy storage

• Capable of avoiding extreme anchor loads during storms

Wave Tuning Research

• A variable-depth, fully-submerged tension leg platform (TLP) was tested in the wave tank facility at Stevens to quantify the wave tuning capabilities of the TLP. The test matrix was scaled at 1:10 based on average waves off NJ/NY/NE

Wave Tuning Research

TLP Shoals

10cm Wave over

a 20cm Buoy

Buoy Motion

Increases with

Wave Steepness

Mild Wave H =5.1cm (2in)

5.1cm, 2.21s Wave – 15cm Platform Depth

Wave Heights:

•Before Platform:

•5.1cm (2.0 in)

•Over Platform:

•12.7 cm (5.0 in)

•Wave Height

Increase: 150%

Mild Wave Results

H =0.051m (2.0in)

Cg = 1.97 m/s at 1.98m tank depth

E = 3.27 J/m^2

P = 6.43 W/m

Tuned Wave

H = 0.127m (5.0in)

Cg = 1.14 m/s at 0.15m platform depth

E = 20.25 J/m^2

P = 23.07 W/m

259% increase in power density

Moderate Wave H = 10.4cm (4in)

10.4cm Wave – 15cm Platform Depth

Wave Heights:

•Before Platform:

•10.4 cm (4.1in)

•Over Platform:

•17.8 cm (7.0 in)

•Increase in Wave Height:

71%

•Note: waves dropped

below the wave wire over

the platform resulting in an

apparent “flat” bottom

Moderate Wave Results

H = 0.104m (4.1in)

Cg = 1.97 m/s at 1.98m tank depth

E = 13.58 J/m^2

P = 26.74 W/m

Shoaled Wave

H = 0.178m (7.0in)

Cg = 1.14 m/s at 0.15m platform depth

E = 39.78 J/m^2

P = 45.32 W/m

69% increase in power density

1:10 Scale Model to Prototype

50m x 12m x 3m Barge 20m x 10m x 2.5m Floats

Wave Energy Harnessing Device (WEHD)

WEHD Sub-Systems

Power Take-Off System

• Surface Float = 800 cubic meters of displacement potential at still water line

• Storage volume, 80 – 300L Accumulators

• = 24m3 = 12m3 working volume

• Storage pressure = 3000psi (200 bar)

• Adiabatic Storage capacity = 303kWh (1.09GJ)

Northeast Wave Energy Region

44017, 45m depth, 23NM offshore

1m wave

• Buoy lift: 410,000kg seawater

• Lift rate: 1 m per 7 s

• Acceleration: 9.8 m/s2

• Input Lift Power: 574kW

• Added Mass (0.5x): 287kW

• 861kW * .35 efficiency = 301kW

1m tuned wave

• Buoy lift: 738,000kg

• Lift rate: 1.8 m per 7 s

• Acceleration: 9.8 m/s2

• Input Lift Power: 1860kW

• Added Mass (0.6x): 1120kW

• 2980kW * .35 efficiency = 1043kW

1.5m wave

• Buoy lift: 615,000kg

• Lift rate: 1.5 m per 7 s

• Acceleration: 9.8 m/s2

• Input Lift Power: 1292kW

• Added Mass (0.5x): 646kW

• 1938kW * .35 efficiency = 678kW

1.5m tuned wave

• Buoy lift: 820,000kg

• Lift rate: 2.5 m per 7 s

• Acceleration: 9.8 m/s2

• Input Lift Power: 2870kW

• Added Mass (0.6x): 1722kW

• 4592kW * .35 efficiency = 1607kW

7m wave

• Buoy lift: 820,000kg

• Lift rate: 7m per 10 s

• Acceleration: 9.8 m/s2

• Input lift Power: 5625kW

• Added Mass (0.75x): 4219kW

• 9844kW * .35 efficiency = 3445kW

44008,66m depth, 54NM offshore

12m wave

• Buoy lift: 820,000kg

• Lift rate: 12m per 12 s

• Acceleration: 9.8 m/s2

• Input lift Power: 8030kW

• Added Mass (0.75x): 6030kW

• 14060kW * .35 efficiency = 4920kW

44025, 36m depth, 33NM offshore

Load Control-Energy Storage

• 75kW for 4 hours

• 150kW for 2 hours

• 300kW for 1 hour (equilibrium-1m wave)

• 600kW for 30 minutes

• 1000kW for 18 min (equilibrium-1m tuned wave)

• 1.2MW for 15 min (equilibrium-1.5m tuned)

• 2.4MW for 7 min 30 s

• 4.8MW for 3 min 45 s

Southern New Jersey

• Southern New Jersey has three proposed offshore wind farms planned to land power cables in Atlantic City. The proposed “Backbone” seafloor power cable, planned to run from Manhattan, NY to Norfolk, VA with a branch into Atlantic City is currently designed to carry 5000MW of electric power, more than 5 times the output of all the planned wind farms. Wave energy can supplement Backbone capacity.

44012, 18m depth, 15NM offshore

44001, 63m depth, 57NM offshore

Business Case

Deploy 5GW (5000 MW) name plate capacity wave farm (1000 grid connected units) for under $5 billion. 5GW = 2.3x Output Capacity of Indian Point Nuclear Power Plant

Demand a premium for “on demand, carbon free, grid quality electric power” at a rate of 0.8x utility’s residential rate.

Produce a minimum annual average of 1GW (1000 MW) of grid quality electric power in the design wave climate ($1.05B/yr @ $0.12/kWh)

Contact Information

Michael Raftery, M.E.Research EngineerStevens Institute of TechnologyDavidson Laboratory711 Hudson St.Hoboken, NJ 07030Email: michael.raftery@stevens.eduPhone: 201 216 8704Fax: 201 216 8214