SOLAR CONCENTRATING POWER

Solar Concentrating Power

Concentrating Solar Power is a method of power generation from solar energy that employs incoming radiation’s thermal energy directly

The four major types of CSP Technologies are Parabolic Trough Parabolic Dish Linear Fresnel Solar Power Tower

Focus type Line focus Point focus

Receiver type

Collectors track the sun along a single axis and focus irradiance on

a linear receiver. This makes tracking the sun simpler.

Collectors track the sun along two axes and focus irradiance at a single point receiver. This allows

for higher temperatures.

Fixed

Fixed receivers are stationary devices that remain independent of the plant’s focusing device.This eases the transport of collected heat to the power block.

LinearFresnel Reflectors Towers (CRS)

Mobile

Mobile receivers move together with the focusing device. In both line focus and point focus designs, mobile receivers collect more energy.

Parabolic Troughs P arabolic Dishes

Parabolic Trough Concentrators

Cost and Efficiencies

Case Baseline Near Term Long Term

Project SEGS VI SEGS LS-4 SEGS DSG

Factors No Storage 10 Hr Storage 10 Hr Storage

Rated Power MW 30 320 320

Capacity Factor 22/34 % 40% 50%

Area/MWSolar FieldOverall

626621166

1122339000

1054534666

Solar To electric Efficiency

10.7% 14.6% 15.3%

Capital Cost (USD/KW)

3972 2999 2907

LEC (USD/MWh) 194 101 49

Investment Cost of a 5 MW Trough plant with 7 Hours of Storage

Time To Large Scale Commercialization

Parabolic Trough Collector Solar Power Plants are the most widely deployed and commercialized CSP Systems

11 working commercial installations worldwide and 20 of the 27 CSP Plants under construction are PTCs

PTCs using mineral oil HTFs and Rankine Cycle Power blocks are fully commercialized technology

Deployment estimated at 15 GW by 2014

Machinery

Key parts of a Parabolic Trough Solar Power Generation Plant are:

The Solar Field The Power Generation System Thermal Power Storage

Solar Field

Solar Fields are made up of a series of Solar Collector assemblies through which the heat transfer fluid is pumped.

Key Subsystems

Subsystem System Used Current Choice Future Choice

Collector Structure LUZ LS 1,2,3; Eurotrough; Solargenix

EuroTrough ReflecTech

Reflector Surface Thick Glass; Thin Glass; Reflective Film

Thick Glass Reflective Film

Sun Tracker Geared; Hydraulic Geared Hydraulic

Receiver Tubes SchottPT; Solel UVAC; Luz Cermet

Schott PTR Solel UVAC

Heat Transfer Fluid Mineral Oil; Molten Salt; DSG Mineral Oil DSG

Collector Interconnect

Flex Hoses; Ball Joints Flex Hoses Ball Joints

Power Generation and Thermal Storage

Subsystem Systems Used Current Choice Future Choice

Thermal Storage Systems

Direct; Indirect Single/Double Tank; Solid Media; Phase Change Media

Indirect Double Tank Molten Solar

Direct Molten Solar; Direct Solid Media

Steam Generators Heat Exchangers; DSG

Heat Exchangers DSG

Turbine Rankine Cycle; OCR; Combined Cycle

Rankine Cycle; Combined Cycle

ISCCS

Cooling Systems Wet; Hybrid; Dry Wet Cooling Hybrid Cooling

Materials/Resources Required

Raw Materials

Steel

Aluminum

Silica/Sand

Chemical Coatings

Polymers

Composites

Rubber

Water

Oils

Salts

Sub-Components

Truss

Torque Tube/Box

Support Pylons

Parabolic Mirror

Reflecting Film

Hydraulic Cylinders

Gears

Hose

Ball Joints

Piping

Blading

Structures

Electronics

Power Electronics

Rotor/Stator

Towers

Earthing

Components

Parabolic Trough

Reflecting Surface

Receiver

Receiver InterconnectTracking System

HTF Oils

HTF Piping System

Molten Salt

Storage Tanks

Heat Exchangers

Steam Generator

Steam Network

Turbine

Generator

Cooling Towers

Final Components

SCA

Heat Transfer Network

Thermal Storage

Power Block

Cooling System

Key Barriers

Size of Plant: CSP cost goes down with capacity and Makes sense only above 10-20 MW.

Reliability Of Components: Key parts liable to short term failure. Also most components nto completely proven

Cumbersome and Expensive Storage: Needs multiple heat exchangers and piping. Capital cost increase of 18%

Shipment and Installation: Suppliers situated in Eur and US. High shipment density and skilled installation required

Geographical Location: Plants generally located where powe isn’t required. Transmission is a difficulty

Opportunities for Indegenization

Local manufacture of trusses and Power Block Design and manufacture of tracking system Film based mirrors and installation services Heat Exchangers

Answers to Questions

Entry into the Power Generation Market

Reasons for late entry into market: Key components- not yet standardized Except Trough Systems, technology is not mature Limitation- Trough/Tower Systems are financially viable

only in large scale >10MW; Dish Systems are expensive Experimental plants require large investments

CSP vs PV

Parameters PV costs Thermal costs

Nominal power MW 50 50

Power efficiency 0.14 0.11

Direct capital cost $/W

5.44 5.6

Indirect capital cost $/w

1.4 1.4

Storage cost$/W 2.2 1,68

O&M% 0.4 4

CSP Storage

Types Method Materials Advantages Lowcost Issues

Direct 2 Tank

HTF storage tanks part of the loop, one hot one cold

Mineral Oil; Molten Salt in towers and experimental direct salt systems

Simplest System Low storage time, large volumes, High pressure storage needed

Indirect 2 Tank

HTF Heats secondary material stored in tanks

Molten Salt Proven, Long Term Storage

High Cost, Heat loss in exchangers, pumping costs

Indirect Single Tank

Hot and cold media stored in same tank, form thermocline

Molten Salt Reduces salt requirement, Lesser cost

Thermocline spread, relatively short term

Direct Solid Media

Media heated by radiation, HTF draws heat from it

Graphite Blocks in power towers

Most Efficient, simple

Experimental, small storage only, high strength tower required

Indirect Solid Media

Pipes pass through solid, media stores heat

Cement, Ceramic Low cost of media Inefficient, high volumes required due to low ∆T

CSP Storage

Indirect Molten Salt storage is currently the most explored and feasible option in Trough and tower systems

Cost Trends: In the case of towers, molten salt direct systems

are the most efficient If solid media storage works out, it could prove to

be the most useful and cost effective Storage technology

Materials/Resources Required

Raw Materials

Steel

Aluminum

Silica/Sand

Chemical Coatings

Polymers

Composites

Rubber

Water

Oils

Salts

Sub-Components

Truss

Torque Tube/Box

Support Pylons

Parabolic Mirror

Reflecting Film

Hydraulic Cylinders

Gears

Hose

Ball Joints

Piping

Blading

Structures

Electronics

Power Electronics

Rotor/Stator

Towers

Earthing

Components

Parabolic Trough

Reflecting Surface

Receiver

Receiver InterconnectTracking System

HTF Oils

HTF Piping System

Molten Salt

Storage Tanks

Heat Exchangers

Steam Generator

Steam Network

Turbine

Generator

Cooling Towers

Final Components

SCA

Heat Transfer Network

Thermal Storage

Power Block

Cooling System

Next Step in CSP

The next technology in CSP is the Solar Power Tower

It has multiple advantages over Trough based CSP while not having any more disadvantages than PCT

The only big problem being that Tower has no track record

Towers have already been made with next generation PCT technologies like Direct Salt and Direct Steam generation

Break Through Technologies

Troughs: Reflective Films on Metal Backing Receivers: Solel UVAC, Selective coatings HTF: Low temperature salts, Direct Steam

Generation Storage: Solid Storage Media Piping: Ball Joints Power Production: Combined Rankine Cycles