IEA comments on the draft Solar Energy Technology Roadmap ...

© OECD/IEA 2010

IEA comments on the draft Solar Energy

Technology Roadmap for South-Africa

CSIR, Pretoria, 18 June 2012

Cédric Philibert

Renewable Energy Division © OECD/IEA 2012

© OECD/IEA 2010

IEA appreciation of the SETRM for SA

More than a good background document

Selects 8 technology areas

Considers market potentials and barriers

Suggests short term actions focusing on R&D needs

The forthcoming « roadmap » or « operational plant » must have other dimensions

Short term and long term (hard or soft) targets

Policy recommendations for implementation

Needs updating

Technologies and thinking evolve quite rapidly!

The IEA is willing to provide constructive comments and promote an integrated approach

© OECD/IEA 2012

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IEA suggestions

1. From a resource analysis (re-) consider the concentrating/non-concentrating trade-offs

For various PV technologies and PV vs. CSP

2. Appraise the role of storage in the context of RSA’s grid needs

3. Consider solar-coal hybridisation

4. Look at all options for process heat

5. Consider the global context for manufacturing

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Excellent direct normal (DNI) not always greater than global horizontal irradiance

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Global normal greater than normal direct…

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To be concentrated or not to be…

Concentration allows reducing PV surfaces

And chosing expensive but very efficient materials

But concentration requires tracking the sun…

While tracking does not require concentration

… and neglects the diffuse light

What justifies a preference for CPV > 1 MW?

Cost comparisons must be case by case

A production profile that better matches demand? Possibly, but this benefit arises from tracking the sun, not from concentration!

Tracking for concentration must be quite precise, and this is expensive, esp. 2-axis! Loose 1-axis tracking much cheaper

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If tracking is justified, then concentration might be…

Unless sacrificing direct light is more justified by the even better output profile of CSP due to its built-in thermal storage capabilities!

Tracking changes the profile

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Btw, need to tilt your PV panels?

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Costs have been sharply reduced The PV module learning curve ($/W, logarithmic scales)

Source: Bnef © OECD/IEA 2012

© OECD/IEA 2010

Cost reductions will continue 2020 2030 2050

Typical turnkey system price (2010 USD/kW) 3800 1960 1405 1040

Typical electricity generation costs

(2010 USD/MWH)*

2000 kWh/kW 228 116 79 56 1500 kWh/kW 304 155 106 75 1000 kWh/kW 456 232 159 112

Cost targets for the residential sector

2020 2030 2050 Typical turnkey system price (2010 USD/kW) 3400 1850 1325 980


(2010 USD/MWH)*


Cost targets for the commercial sector

2020 2030 2050

Typical turnkey system price (2010 USD/kW) 3120 1390 1100 850


(2010 USD/MWH)*


Cost targets for the utility sector

Notes: Based on the following assumptions: interest rate 10%, technical lifetime 25 years (2008), 30 years

(2020), 35 years (2030) and 40 years (2050). Sources: IEA 2010d, Bloomberg New Energy Finance, IEA data.

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Modules now only half system costs

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PV & CSP: peaceful coexistence?

PV and CSP compete on markets (California)

Good time-match between demand and resource reduces the value of storage

CSP more expensive than PV but still justified…

Where peak extends or occurs after sunset

When high-share of PV saturates demand at noon

Depending on round-trip efficiency and costs of storage and grid connection

Flexible CSP with thermal storage may allow for more PV

Saudi Arabia plans, e.g., for 16 GW PV and 25 GW CSP by 2030

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Concentration and efficiencies in STE generation (CSP plants)

Source: Tardieu Alaphilippe, 2007. © OECD/IEA, 2011 © OECD/IEA 2012

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IEA suggestions







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Technologies: solar thermal electricity

Key value of STE/CSP is in thermal storage to better match demand More efficient and cheaper than electrical storage

Many different designs and options

Source: Torresol Energy

© OECD/IEA, 2011 © OECD/IEA 2012

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Footprints

« Fresnel very compact, troughs more demanding, towers even more… ». True?

Fresnel are compact… but as a result cosine losses are more important than for troughs

reduced output, weak mornings and evenings

Towers can be more or less compact

Depending on the ratio tower height/field size

Footprints should be compared by annual energy (GWh) , not by capacity (MW)

Storage would make comparisons even less relevant

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Comparisons that matter

Comparing plants with similar electric capacities and different storage capabilities is confusing

Does not help appreciate the cost of thermal storage

Better compare plants with similar solar fields and different electric capacities (MW)

The size of the field dictates the yearly output (GWh)

The ratio yearly output on capacity gives the capacity factor (“full load hours”)

The size of storage does not dictate the use

Storage reduces the levelised cost of electricity in some cases but not all

Its role is to increase the value of CSP!

© OECD/IEA 2010

Technologies: solar thermal electricity

Source: ACS Cobra


Key value of STE/CSP is in thermal storage to better match demand More efficient and cheaper than electrical storage

Many different designs and options

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Possible roles of storage

Thermal storage can be used to shift production, to extend it to base load or to concentrate it to super peak load © OECD/IEA, 2011

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Time-of-use payments are key

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Load curve & merit order with PV

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Load curve & merit order w. CSP

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Stored Heat =∑ mCp ΔT

Large / Smaller ΔT ≈ 278°C/90°C Low Temperature Storage Requires ≈ 3X mass

Stored Heat is Proportional to ΔT

. Tower

566°C

288°C

~378°C

288°C

Low Temperature Storage ~ 3X Cost per MWt

Troughs

Temperatures and storage costs

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DSG and storage: not that easy…

Poor heat transfers from the steam…

3-step storage considered optimal…

Sensible storage for both preheating water and superheating steam

Latent storage for vaporisation

… but not commercial (yet?)

New options developed by BrightSource

De-superheating steam and molten salts

Only for small storage in sub-critical plants

3-tank molten-salt storage for supercritical plants

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IEA suggestions







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Back-up/hybridisation

Firming capacities

Increase the solar share in the mix

Walk down the learning curve

Currently in use: Back-up or routine fuel use in PT plants

Steam augmentation in bottoming cycles (ISCC)

Fresnel pre-heating feedwater in coal plants

Options to be developped

Main steam augmentation in efficient coal plants

Hybrid solar-gas with combined cycle

Source: PEGASE/CNRS.


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Hybrid solar-gas…

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Only exist at very small scale

Developing larger air receivers challenging

Steam turbine for combined cycle cannot be atop the tower

Less relevant for South Africa

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Coal-solar add-ons and hybrids

Benefit from the efficiency of modern coal plants

Coal plants have too much high temperature heat

More solar kWh for the buck

Need not to pay for the (whole) turbine, alternator, balance of plant, connecting lines…

Add-ons (on existing plants): mostly fuel savers

Add-ons can boost the power to the extent of the difference between nameplate capacity and gross turbine and alternator capacities – few percent

Hybrid (Greenfield) plants: solar boosts or saves

Fuel saving or booster mode – what the grid needs

Boiler constraints may lead to « booster-saver » hybrid mode

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Hybridisation options for a 1000 MW supercritical coal plant

Hybridization option Preferred solar

collector

Marginal

solar eff.

Max. solar heat

input in MWth

(% of boiler Pth)

Max. Xtra

output

MWe

HP feedwater preheating DSG Fresnel to HX,

HTF PT heating water 45% 350 (16%) 160

LP feedwater preheating Flat plate/evacuated

tubes + Fresnel /PT 18% 350 (16%) 60

Main HP (300 bars) steam

(1)

Molten salts CRS,

DSG CRS? HTF PT? 48%

(45%)

1000 (45%) (2) 480

Reheat steam (60 bars) (1) DSG Fresnel DSG,

DSG CRS 42%

(40%)

250 (11%) 100

Preheating of secondary

combustion air (3)

CRS / Fluidized bed

or volum. receiver 50% 600 (27%) 300

(1) Small efficiency differences with different temperature levels between 450. and 600°C for main steam, 620°C reheat, since there is an excess of high-grade heat in the boiler (2) Engineering issues regarding boiler design may reduce this figure in practice (3) Long-term technological option

Source: Siros, Le Moulec & Philibert, forthcoming © OECD/IEA 2012

© OECD/IEA 2010

Non-concentrating solar thermal power?

Solar ponds have very low efficiency

Evacuated tubes/CPC collectors best prospects

Using organic rankine cycles

But more likely in hybridisation with coal plants

Solar chimneys (“updraft towers”)

Not being developed as stand-alone devices…

Experimental non-

concentrating solar

thermal electricity

near Nice (France).

Source: SAED

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Solar chimneys?

Costs of receivers deemed too high

As benefits grow with the square of the size, difficult to justify small-scale

demonstration

But… solar chimneys could be considered for dry-cooling of CSP plants

A development of the known Heller scheme

Natural Draft Cooling Towers at the Shahid Rajai

TPP (4 x 250 Mwe), Iran

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IEA suggestions







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Solar water heating is a must

Source: W. Weiss

SWH recently installed in South Africa

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Hot water in Saudi Arabia

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Solar cooling

Some large installations, but costs are often too high compared with “conventional” cooling devices run by (solar) electricity (centralised or decentralised)

Air-conditioning daytime peak loads help make PV competitive

Reversible ground-source heat pumps to respond to both cooling and heating demand with renewable electricity?

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ECD

/IEA

, 20

11

Resource and demand match well

Thermally-driven cooling?

Cooling is ultimately work, not “heat”…

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Solar heat for industry & services

Large heat needs at various temperature levels in industry and services; low-temp. solar heat available everywhere, demand all year round

High-temp. solar heat under hot and dry climates

Estimated industrial heat demand by temperature range in Europe, 2003

Sou

rce: Wern

er, 20

05

-20

06

PJ

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Source: AEE INTEC. Source: Deepak Gadhia

Solar water heaters in a service area (Austria) Cooking with Scheffler dishes (India)

Source: SolarWall.

Solar air drying of coffee beans (Columbia) Experimental mid-size industrial solar oven (France)

Source: Four Solaire Développement. © OECD/IEA 2012

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Solar heat reaches competitiveness

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Price of low-temperature solar heat for heating networks and large industrial systems

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Co-generation from CSP: an example from Morocco Oriental?

Electricity demand is maximum and summer; output from CSP plants maximum in Spring

Except for specific circumstances (large hydro, possibly with pump-back scheme), storage over several months way too costly

However… demand of high-temperature process heat for sugar refineries is maximum in May, June and July…

Excess or all solar steam could be used for sugar in three months, and electricity generated in the rest of the year…

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Solar fuels for inter-seasonal storage

CSP has excess power in Spring, lacks in winter

Storing hydrogen is not easy, consumes energy

Liquid fuels, but ammonia, have carbon atoms

One option could be to store reduced metals as means to generate hydrogen at will

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Many uses for industrial heat & fuels

SETRM for SA notes the possibility of melting scrap aluminum

Solar heat in coal-to-liquid manufacturing

Would bring life-cycle emissions down, close to those of oil products

Sasol plant in RSA the largest CO2 point-source in the world

Full inventory of options by temperature levels should be made

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PV: Where do we stand?

Capacities added in 2011: 27.5 GW

Cumulative: 67.5 GW

6 markets >1 GW

46% of newbuilt capacities in Europe

0

10

20

30

40

50

60

70

80

2005 2006 2007 2008 2009 2010 2011

GW

RoW

China

US

Spain

Japan

Italy

Germany

© OECD/IEA 2010

Competitive markets emerge

Grid parity in Germany, Italy, Mexico…

Newbuilt systems in Germany: no more than 80 to 90% of power benefitting from FITs

Net metering: Italy, Brazil, Denmark, Spain…

Compétitiveness with power from oil:

Islands, Middle East, Japan, Italy…

Favourable where demand peaks at hot mid-days

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Twin market changes

From European to global markets

From subsidised to (partly-) competitive markets

Will eventually more than offset recent FIT cuts

Global manufacturing capacity over 50 GW/a

2012 and 2013 difficult for companies…

And analysts: short term market assessment difficult!

May not be the good timing for developing PV cell and module manufacturing capacities

Significant share of value is local anyway

Prospects for manufacturing thermal collectors and CSP materials significantly greater, esp. Fresnel and solar towers

© OECD/IEA 2010

An integrated approach should…

Distinguish the needs for heat and work

At the various temperature pressure levels

Looking for possible complementarities

Consider variations in time at all scales

Aim at having energy prices reflect costs

In real time and place, as much as possible

Consider the trade-offs between decentralised and centralised electricity generation (and storage), taking grid costs into account

© OECD/IEA 2011

Growth of PV by2035 in the WEO scenarios

Scenario New Policies 450 450 delayed-CCS

Capacities 2035 499 GW 901 GW 1030 GW

Annual market 22.1 GW 38.5 GW 43.7 GW

IEA comments on the draft Solar Energy Technology Roadmap ...

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