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www.service.power.alstom.com ALSTOM 2010. All rights reserved. Information contained in this document is indicative only. No representation or warranty is given or

should be relied on that it is complete or correct or will apply to any particular project. This will depend on the technical and commercial

circumstances. It is provided without liability and is subject to change without notice. Reproduction, use or disclosure to third parties,

without express written authority, is strictly prohibited.

9DESER00021

THERMAL POWER

Integrated Solutions

Plant|EnvironmentalSolar Boost

In many regions of the world sustainability is becoming a more stringent condition, makingpower generators address the demands by increasing the renewable energy sources in theirportfolio. The sun provides an unlimited and free available energy source and the fossil firedpower plants offer a highly efficient and stable water steam cycle. Based on more than 20

years of experiences in solar thermal applications Alstom believes that solar is part of theoverall solution to reduce CO2 emissions and to benefit from a balanced portfolio of fuels.

Alstom can provide several hybrid solutions to combine the environmental advantages of asolar-thermal power plant with the economic and technical advantages of a fossil fired powerplant, thus allowing power generators to benefit from the best of both worlds.

Customer Benefits

Increase power generation or

reduce coal consumption

Reduction of Green House Gas

Emissions

Improved reputation of coal firedpower plant due to generation of

renewable electricity

No cost risk for solar energy

Usage of local resources

BackgroundWith the increasing globalenvironmental awareness andefforts to increase renewable

energy in many countries,generation from renewablesources is often further subsidised

and supported to improve theeconomics.One economic option is to reducethe specific coal consumption andwith this the specific CO2emissions by combining fossilenergy with an input from a CO2

neutral renewable energy source

resulting in a so-called hybrid

power plant. For the effectivecombination a high level ofunderstanding and designcapability for power plantoptimised integration is necessary.The integration of an additional

heat source in an existing water

steam cycle is a proven

technology. In the case of SolarBoost the additional heat comesfrom a solar field.Solar Boost offers the possibility tochoose the solution that fits to theoperators goals and the specific

local conditions.

Figure 1: Solar Boost TechnologiesSource: David Baker, Pictolia.com


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The Idea of Solar Boost

The solar integration workingprinciple is a feed water partialbypass system: depending on thechosen solution, the feed water isheated up directly by the solar fieldor indirect through an additionalheat exchanger by the solar energy(Figure 2).Depending on the availableamount of solar heat a fraction ofthe feed water bypasses a part ofthe pre-heating train and is heated

by the solar energy. With this theconsumption of extraction steamof the turbine for the pre-heatingis reduced.The reduction of extraction steamcan be used

Either to reduce the live steammass flow at a constant power

output allowing a strong fuelconsumption reduction andwith this an important CO2emission reduction (Figure 3)

Or alternatively the generationof electricity can be increasedat a constant coal inputallowing the operator toproduce green MWs(Figure 3, additional poweroutput with same fuel

consumption).

The existing solar technologies(Figure 1), the linear focusedcollectors such as Fresnel andParabolic Trough technologies andthe two-axis collectors such as theTower technology fit perfectly to

Solar Boost and its integrationtemperature.

Benchmark with othertechnologies

Compared with a stand-alonesolar thermal power plant a hybridpower plant offers severaladvantages:

At times with low solar

radiation (cloudy sky) or noradiation (at night) the plantcontinues to work as aconventional power plant.Operation is not depending onsolar radiation.

No need for thermal storage.

Solar-only plants especiallywith linear focused collectors,have lower cycle efficienciescompared to coal-fired plants

due to their limited live steamparameters. In a hybrid plantsolar collectors can beoperated at their optimaltemperature level and coal isused to produce optimised livesteam parameters.

Figure 2: Solar Boost Integration Potential Locations

Coal

Time of day

Load

Curve

Reduced Coal Consumption

Solar

Coal

Time of day

Load

Curve

Additional Power Output

Solar

Figure 3: Hybrid electricity generation


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The existing infrastructure ofthe coal plant can be adapted

for the solar part. With thisthe investment costs arereduced.

The industrial usage of the

power plant site is alreadyaccepted which leads to a

simplified permitting process. The solar field can be

upgraded stepwise.Comparing the investment costs

and the solar-electrical efficiency

of Solar Boost with solar-only orphotovoltaic plants with simplified

assumptions, it can be seen thatSolar Boost offers a bettercompromise between efficiencyand Investment costs (Figure 4).

Solar Boost in Numbers

Table 1 shows a simplifiedexample calculation of Solar Boostimplemented in a typicalexemplary 600 MWel power plant

in South Africa. In Figure 5 theSolar Boost collector size iscompared to the typical surface ofa coal plant.

As the final solar generation andthe economics of the solarapplications depend strongly onthe specific site conditions thisexample gives only an overview ofthe technical parameter range.

Figure 4: Benchmark with other technologiesReference: Solar Only Linear (linear corresponds to an average between Fresnel and Parabolic

Trough technologies), Estimation depends on meteorological data, integration location, collector

technology

General Data

Location - South Africa

Coal Unit MWel 600Solar Technology - Fresnel Collector

Integration Location - Top HP bypass

Field Surface m2 200 000

Collector Surface m2 100 000

Radiation Values

Max. DNI 1) W/m 1 090

Annual DNI 1) kWh/(m2*a) 2 300

Efficiency(based on DNI 1))

Max. solar to electr. % 20,6Ann. mean sol-electr. % 13,1

Electrical Generation

Ann. generation MWhel/a 33 900

Max. Capacity MWel 25,4

Table 1: Example, 600 MWel Coal Unit1) DNI: Direct Normal Irradiation

Coal Plant

approx. 1 km

Solar Field

ca. 0,2 km

Figure 5: Surface of power plant

and solar field for example

calculation


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Customer Benefits

Environment-friendly solution:

o To increase powergeneration at constant coalinput

o Or to decrease fuelconsumption at a constantelectrical power generationlevel.

Maximum solar energy attimes of usual maximumenergy requirements: middleof the day

Reduction of CO2-Emissions

Increased acceptance in public

opinion due to production ofrenewable energy

No energy cost risk for solar Usage of a local energy

resource

.Solution Approach

1. Feasibility Check-Up

Depending on different plantcharacteristics Alstom will

determine the most suitable optionfor the customers plant dependingon: Customers targets Meteorological datao Solar radiationo Ambient temperature

Available space near thepower plant

Presence of incentives in thecountry

Technical data of existing

power plant

The Feasibility Check-Up includes:

Check of impact on affectedcomponents: e.g. turbine and

water-steam-cycle capability

for additional steam flow Selection of the most

appropriate configuration Determination of approximate

solar electricity output Layout recommendation Cost estimate Implementation schedule

2. Implementation

The implementation of Solar Boostis based on the results of theFeasibility Check-Up.

Integrated Expertise

To evaluate the Solar Boostimpact on all major components(turbine, boiler, condenser, pre-heating train) and to help thecustomers to make appropriatedecision Alstom offers a broad

experience for the integration ofsolar energy in a conventionalpower plant in providing

Full service supplier -

Capability for integratedsolutions and plant-wideoptimisations (including I&Cand civil work)

Experience with all maincomponents of the watersteam cycle

Experience with the

integration of additional heatsources in a water steam cycle

(e.g. topping gas turbine) 20 years experience servicing

and maintaining solar plantsand their associatedequipments.

Your local service partner:

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