NRG Energy, Inc. Confidential

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CDAWG November 13, 2013

Ivanpah Solar Project: Helping to meet California’s Climate Change Goals

byShankara Babu, ESH Manager, NRG O&M

Doug Davis, Senior Compliance Manager, BSE

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Corporate Organization

Solar Partners Holdco, LLC - Equity Investors NRG Google BrightSource

Three Individual Projects Solar Partners II – Ivanpah #1. Selling power to PG&E. Solar Partners I – Ivanpah #2. Selling power to SCE. Solar Partners VIII – Ivanpah #3. Selling power to PG&E.

Southern California Edison Transmission Upgrade Implementing their El Dorado to Ivanpah Transmission

Project (EITP)

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CSP - Technologies

Central Receiver / Heliostats

Parabolic troughs

Parabolic dishes

Linear Fresnel Reflectors

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Energy from Sun

• Insolation is a measure of solar radiation energy received on a given surface area and recorded during a given time.

• Direct insolation is the solar irradiance measured at a given location on Earth, excluding atmospheric diffused insolation.

• Absorbed solar radiation is converted to thermal energy, causing an increase in the object's temperature.

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Overview

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Power Block Configuration

SOLAR RECEIVER STEAM GENERATOR (RILEY POWER)Concentrated sunlight converts water in a boiler to high-temperature steam.

HELIOSTATS (BRIGHTSOURCE)Software-controlled field of mirrors concentrate sunlight on a boiler mounted on a central tower.

OPTIMIZATION / CONTROL SOFTWARE (BRIGHTSOURCE)Solar Field Integrated Control System is the proprietary optimization software to manage heliostat positioning and optimize concentrated sunlight on the boiler.

TURBINE (SIEMENS)Steam powers turbine to produce electricity – then is converted back to water through an air-cooled condenser.

AIR-COOLED CONDENSER (SPX)Environmentally friendly

in design, using 95% less water than competitive technologies.

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Overview

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Site

Geography and Footprint• Project, about 3600 acres• Edge of U1 SF to edge of

U3 SF = 5 miles• Unit 1 to Unit 3 Tower =

3.2 miles

Tower• Height 459” steel

structure with the boiler on top

• Tuned Mass Damper

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Solar Steam Generator

Boiler• 2646 psig / 1054 F• Evaporator• Super Heater• Reheat

Controls• IR Cameras – 2/wall, total 8• Heat Flux Sensors – 24 pairs

of TCs embedded in SH, RH, and EVA tubes.

• About 1180 loops, 120 MOVs (networked), 17 CVs

• 100% steam bypass, no sky valves

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Solar Steam Generator Layout

Superheat

Evaporator

Reheat

Protection Panels

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Steam Turbine Generator

Turbine• Siemens SST-900• HP and IP Turbine• HP – 7200 RPM• IP – 3600 RPM

Generator• 135 MVA• 3600 RPM

Design• Fast Startup• Daily Cycling

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Air Cooled Condenser

ACC• Water Consumption limited to

100 acre-ft / year• 3 Streets of 5 fans / Unit• 2 Speed

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Solar Field

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Focus length too long

Focus length too short

Heliostat focused on SRSG

System Components Overview: Focal Length

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System Components: Heliostat

LH-2.2 Heliostat Mirrors

Metal support structure

Dual-axis drives

Heliostat controller

Focuses sun on SRSG Under SFINCS control

System Components: Heliostat

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Solar Field Control System (SFINCS)Heliostat desired aiming points calculating to: • Flux vs Load balancing • Implement quick flux reduction / defocusing • Measuring SRSG skin temperature• Alert on crossing temperature limits

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Solar Field Control System (SFINCS)

Inputs: • Heliostat calibration data,

heliostat reflectivity • Weather data • Skin temperature of panels • SFINCS state, operation mode

and sensor info • DCS SP & control parameters

Outputs: • HAPA (Heliostat Aiming Point

Array): a collection of aiming points (1/heliostat), sent to SF through SFC

• Is there potential flux for operation?

• Is tracking active (per SRSG section)?

• Process information, flux and temperature maps

• Alarms on flux / temperature deviation

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Insolation Matr

East Weather Statio

Tower Weather Statio

Insolation Weather Statio

West Weather Statio

Weather System

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Weather Station Measurements Radiation

Direct Normal Radiation (DNR) - Critical for optimizing performance Global Horizontal (GH) radiation

Diffused Horizontal (DH) radiation

UV horizontal radiation

Wind Wind speed in different locations - Critical for SF safety during high winds Wind direction

Ambient weather Ambient temperature

Relative humidity

Barometric pressure

Rainfall

General Description

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Instrumentation

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California Renewables Portfolio Standards [RPS]

Under California's Renewables Portfolio Standard (RPS) statutes, all sellers of electricity in California, including publicly owned utilities (POUs), investor-owned utilities (IOUs), electricity service providers (ESPs), and community choice aggregators (CCAs), are required to procure a portion of their electricity retail sales from eligible renewable resources to meet the following goals:

• 20 percent by the end of 2013• 25 percent by the end of 2016• 33 percent by the end of 2020

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Environmental Considerations

• Flora and fauna – Protected SpeciesDesert Tortoises Succulent Desert Plants Weed Management

• Water - 100 acre-ft/year2 – onsite wells provide all the water

• Air – EmissionsTitle VGHS/cap and trade

• Avian and Bat - nesting and migratory birdsSurveysMonitoringReports

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Ivanpah Stats

7.8 Million man-hours worked without a lost time accident

2600 employees at the peak of construction

70 O&M employees post construction

2.3 Billion

3 units generating 373 MW

Will power 140K homes

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Questions?