Ocean Energy Overview:Wave Power & Tidal Power

May 10, 2007

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Wave Power

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Waves Generated by Wind Over Water

Wave generating area

Stochastic resource but possibly predictable 1 to 3 days in advance

Waves are a concentrated form of solar energy

Temperature and pressure differences give rise to wind

Wind blowing over water generates waves

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Wave Power Overview

What is wave power? For PG&E, opportunity to extract renewable energy from waves along northern coast of

California Most wave energy conversion (‘WEC’) devices are deployed on surface of water

Like wind turbines, multiple WEC devices are aggregated in ‘farms’ Operate in varying depths (60-600 feet) Nascent technology (mostly pre-commercial)

California has high potential PG&E service territory borders 600 miles of Pacific coastline

High wave power densities suggest good economics Potential annual energy production could be as high as 48,000 GWh

Wave power could make a significant contribution to future RPS goals

Permitting of wave power plants follows FERC hydropower licensing process Many stakeholders – environmentalists, fishermen, surfers, etc. Roughly 5 year process expected for development license grant

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Wave Power Project Overview

Activities completed Hired EPRI to evaluate and screen potential California sites Hired consultant to confirm EPRI evaluation methodology Filed FERC preliminary permit applications for Humboldt & Mendocino Began stakeholder outreach

Current activities Launching feasibility studies

Confirm wave power resources Consider immediate constraints (shipping, grey whale migration, fishing,

etc) Identify possible technologies Understand installation, operations, and maintenance Develop energy production and economic models

Continuing outreach

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Potential California Wave Power Generation Selection criteria for initial

sites Grid interconnection Wave resource Port infrastructure (deepwater

ports shown in green) Local support

PG&E filed two FERC preliminary permit applications (40MW each) Humboldt County (Eureka) Mendocino County (Fort Bragg)

Wave power plant Multiple wave energy conversion

devices arranged in an array Leading devices float on surface

of water 0.5-10 miles offshore Connected to land via subsea

cable

Humboldt Bay

Noyo Harbor

Bodega Bay

SF Bay Area

Half Moon Bay

Monterrey Bay

Morro Bay

Santa Barbara

Los Angeles

San Diego

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Mendocino and Humboldt WaveConnect Projects

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WaveConnect Project Overview

PG&E is lead project developer

PG&E obtains site control and conducts initial feasibility analyses

PG&E develops infrastructure to evaluate, test, and deploy various WEC devices

Open process for device selection

Individual WEC device developers only responsible for device-specific permitting

Project is scaled up to 40 MW total

Contributes to post-2010 RPS goals

PG&ESubstation

Junc

tion

Box

Pilot PlantDevice A

Pilot PlantDevice B

Demo Device A

Demo Device B

Demo Device C

Shared O&M Facilities

Wave Direction

WEC Device A

Offshore Infrastructure Onshore Infrastructure

Representative aids to navigation

Sub

sea

Tra

nsm

issi

on

Ca

ble

WEC Device BWEC Device C

PG&ESubstation

Junc

tion

Box

Pilot PlantDevice A

Pilot PlantDevice B

Demo Device A

Demo Device B

Demo Device C

Shared O&M Facilities

Wave Direction

WEC Device A

Offshore Infrastructure Onshore Infrastructure

Representative aids to navigation

Sub

sea

Tra

nsm

issi

on

Ca

ble

WEC WEC Device

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Overview – Wave Technologies

OPD Pelamis Wave Plant (‘Farm’) UK Wave Hub Wavebob

Ocean Power Delivery PelamisOcean Power Technology

PowerBuoy TMAquaEnergy AquaBuOY

Devices and technologies pictured for illustration / discussion only Does not reflect or imply any PG&E preference

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Tidal Power

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Tides Governed by Earth-Moon-Sun

Tidal changes in sea level occur as Earth rotates beneath bulges in ocean envelope, which are produced by solar and lunar gravitational forces and centrifugal forces

MOON’S ORBIT

North PoleEarth rotates counter-clockwise

Resource Variable but Predictable

Greatest range occurs when sun and moon

pull in same direction (spring tide)

Weakest when sun and

moon in opposition (neap tide)

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North America Tidal Power Potential

Tacoma Narrows, WAPower density = 1.7 kW/m2

Site energy flux = 0.93 TWh/yr Western Passage, ME

Power density = 2.9 kW/m2

Site energy flux = 0.91 TWh/yr

Muskeget Channel, Martha’s Vineyard, MAPower density = 0.95 kW/m2

Site energy flux = 0.12 TWh/yr

Knik Arm, Anchorage, AKPower density = 1.6 kW/m2

Site energy flux = 1.0 TWh/yr

Golden Gate, San Francisco,CAPower density = 3.2 kW/m2

Site energy flux = 2.08 TWh/yr

Many good sites Southeast AK and BC

Minas Passage, NSPower density = 4.5 kW/m2

Site energy flux = 8.9 TWh/yr

Head Harbor, NBPower density = 0.94

kW/m2

Site energy flux = 0.2 TWh/yr

Many good sites in NB and NS

A few good sites in Puget Sound

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Tidal Power Overview

What is tidal power? For PG&E, opportunity to extract renewable energy from tidal flows

entering and exiting San Francisco Bay For SF Bay, tidal turbines are most likely technology

Deployed underwater, totally submerged Like wind turbines, multiple turbines are aggregated in ‘farms’ Nascent technology (mostly pre-commercial)

SF Bay has been identified as a high potential site for tidal power

Permitting of wave power plants follows FERC hydropower licensing process Many stakeholders – environmentalists, fishermen, commercial shipping,

etc.

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Tidal Power Turbines

Verdant Power Turbine – East River Project – Installation Illustration

MCT Seaflow- SeaGen Turbines – UK Installation

Devices and technologies pictured for illustration / discussion only Does not reflect or imply any PG&E preference

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USGS Bathymetry Map of SF Bay

Ocean

Bay

maximum depth = 377 feet

Source: http://pubs.usgs.gov/sim/2006/2917/sim2917.pdf

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USGS Bathymetry Map of SF Bay

Bay

Ocean

Source: http://pubs.usgs.gov/sim/2006/2917/sim2917.pdf

maximum depth = 377 feet