Solar electricity production with Organic Rankine Cycle turbines[INTRO-DRAFT]

Maria Kaninia27/05/2011

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“Standard” technologies for solar electricity - 1 Photovoltaics: dominant “mainstream” technology

(large-scale plants, roofing)

Feed-in tariffs decreasing to reach grid parity

flat crystallic

panels

thin-film (roofing)

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“Standard” technologies for solar electricity - 2

“Standard” solar thermal plants = optical concentrators + mechanical heat engines + storage option

(molten salt) large-scale (~ 10-100 MWe)

power tower

linear Fresnel array

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“Innovative” thermal small-scale technologies for solar electricity - 3

parabolic dish concentrator (tracker) + Stirling heat engine high direct normal insolation required (arid regions, no clouds) not yet widely deployed commercially in Europe

dish Stirling (25 kWe)

Plataforma Solar de Almería

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Resource: low grade solar heat (harvested with solar flat plate

collectors)

Business opportunity: feed-in tariffs for solar thermal power plants (Greece: €250/MWhe)

Financial constraint: medium-scale installation + size of investment (~100 kWe , ~100 k€)

Proposed conversion technology: Organic Rankine Cycle

Specific project location and environment conditions: Western Greece

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Organic Rankine Cycle thermodynamic cycle

similar to “classical” Rankine cycle of steam turbines “inverse” refrigeration cycle

working fluid: organic substance (e.g. refrigerant fluid) low vaporisation temperature low pressure

binary ORC cycle: established commercial application for power generation from geothermal low-enthalpy resources (e.g. ORMAT, TURBODEN)

ORC system prototyped in

1961 by Harry Zvi Tabor

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ORC sub-cycle #1: hot “resource” thermal oil

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ORC sub-cycle #2: organic fluid

typical

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ORC sub-cycle #3: cooling water

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Solar collectorsno optical concentrators

array of series-connected flat plate solar collectors thermal oil (low pressure) at temperatures above 100oC intermediate storage

design approach•Overdimensioning of the solar collectors array

•Implement storage

•Achieve maximum nominal output from ORC system

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Equipment: ORC system, Purecycle® Nominal net output: 260 kWe

Reversed centrifugal chiller Refrigerant R245fa

CF3CH2CHF2 pentafluoropropane

(boiling point @1 atm = 14.9oC)

centrifugal compressor centrifugal

“expander” (+generator)

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Project data Project assumptions:

location: Messologhi, Western Greece solar resource: TH = 100oC

(overdimensioning) additionalstorage to “stabilise” output heat sink temperature: TL = ~ 25oC

(seawater) low ratio direct / global irradiation

Resource: Approximately 4kWh/m2/day =

1460kWh/m2/yGlobal irradiance - fixed plance

0

100

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4:48 7:12 9:36 12:00 14:24 16:48 19:12

W/m2 JAN

JUL

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Location of intended project•actual project

•“soft version” presentation

•“test-drive”

•comments