Calculation of energy payback time of PV and its ... - Swissphotonics

Calculation of energy payback time of PV and its determinants Presentation at the Swiss Photonics Workshop Dübendorf, October22th 2013

Hans-Joerg Althaus PhD LCA expert / scientific coordinator [email protected]

The principle of Energy payback time calculation 𝐸𝑃𝐵𝑇 𝑦𝑒𝑎𝑟𝑠 = 𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑣𝑒𝑠𝑡𝑒𝑑 𝑖𝑛 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑠𝑢𝑏𝑠𝑡𝑖𝑡𝑢𝑡𝑒𝑑 𝑏𝑦 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝑝𝑒𝑟 𝑦𝑒𝑎𝑟 or

𝐸𝑃𝐵𝑇 𝑦𝑒𝑎𝑟𝑠 = 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑣𝑒𝑠𝑡𝑒𝑑 𝑖𝑛 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑠𝑢𝑏𝑠𝑡𝑖𝑡𝑢𝑡𝑒𝑑 𝑏𝑦 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝑝𝑒𝑟 𝑦𝑒𝑎𝑟 H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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The principle of Energy payback time calculation 𝐸𝑃𝐵𝑇 𝑦𝑒𝑎𝑟𝑠 = 𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑣𝑒𝑠𝑡𝑒𝑑 𝑖𝑛 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑠𝑢𝑏𝑠𝑡𝑖𝑡𝑢𝑡𝑒𝑑 𝑏𝑦 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝑝𝑒𝑟 𝑦𝑒𝑎𝑟

H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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Definition of “primary energy” • Energy embodied in natural resources prior to undergoing any human-made conversions or transformations.

• Energy contained in raw fuels, and other forms of energy received as input to a system. • Can be non-renewable or renewable.


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What is the “primary energy” of different sources? • Fossil fuels: lower or upper heating value Value choice introduces ambiguity. • Natural Uranium: various methods Differences one fossil order of magnitude! • Substitution: how up muchto primary energy would be needed to produce the same amount of electricity? • Average thermal efficiency of nuclear power plant (ca. 32%)  Important to choose consistent values for • Energy content in fissile isotope (considering remaining fissile isotopes in nuclear waste or not) sources! all energy • Solar: various methods  Important to compare only EPBT values • Irradiation from different theyorare consistent! • Harvested (by PV (cell,studies module orif system) thermal collector)


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The principle of Energy payback time calculation 𝐸𝑃𝐵𝑇 𝑦𝑒𝑎𝑟𝑠 =

𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑣𝑒𝑠𝑡𝑒𝑑 𝑖𝑛 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚1) 𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑠𝑢𝑏𝑠𝑡𝑖𝑡𝑢𝑡𝑒𝑑 𝑏𝑦 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝑝𝑒𝑟 𝑦𝑒𝑎𝑟

1) For production, use and end of life but without solar irradiation on PV modules during use phase


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How to calculate primary energy invested in PV system?

chain of production LCA H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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How to do life cycle assessment? Goal definition

Life Cycle Model

Life Cycle Inventory Resources

Disposal

Emissions

Use Materials

Production

Product

Energy Waste

Discussion

LCA Life Cycle Impact

(ISO 14’040) Assessment

Cumulative Life Cycle Inventory Resources


System per functional unit

Emissions

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Model of the Product system of PV power generation

Reference function H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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Production of PV cells (thin film Si)

Glass Electricity

ZnO H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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Influence of production location 120%

CED Non-renewable

100% 80% 60% 40% 20% 0% Electricity, Switzerland

Electricity, Europe


Electricity, China 12

Product system of PV power generation

Central Europe 100% South Europe 170%

Reference function H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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Ambiguities in LCA (of PV system) • System boundaries • Cut-off criteria • Inclusion of infrastructure • Inclusion of R&D • Principles for modeling multi-functionality of systems • Data sources • Choice of background data


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Energy payback time; principle 𝐸𝑃𝐵𝑇 𝑦𝑒𝑎𝑟𝑠 =

𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑣𝑒𝑠𝑡𝑒𝑑 𝑖𝑛 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚1) 𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑠𝑢𝑏𝑠𝑡𝑖𝑡𝑢𝑡𝑒𝑑 𝑏𝑦 𝑃𝑉 𝑠𝑦𝑠𝑡𝑒𝑚 𝑝𝑒𝑟 𝑦𝑒𝑎𝑟

1) For production, use and end of life but without solar irradiation on PV modules during use phase


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What energy is substituted by PV electricity? Coal & lignite Share of electricity produced by fuel [%]

40

0

Nuclear

Renewables

Natural gas

Renewables Oil

1990


2004Source: EEA 16

What energy is substituted by PV electricity? CED Non-renewable [kWh/kWh]

CED Total [kWh/kWh]

4.5 4 3.5

3 2.5 2 1.5 1 0.5 0 Electricity, Electricity, Electricity, Hydro Switzerland Europe China Electricity

Wind electricity


Nuclear UCTE UCTE oil electricity natural gas electricity electricity

UCTE coal electricity

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Examples CED System electricity generated [kWh/m2] [MJ/m2] Central Europe South Europe Crystalline Si

6500

mc-Si

5000

Ribbon-Si

3500

Cd-Te

1500

Amorpous Si

1900

3530

6000

Values 3295 would be 5600 ca. 20% higher 5000 2940 for production in 2235 4500 China 2650

3800

Exemplary values in reasonable range for PV system produced in Europe. CED of substituted electricity from ecoinvent v2.2 H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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Energy payback time [years]

Examples

6 5

Differences in 4 electricity Value 3choice introduces ambiguity. generated and 2 Differences up to a factor of 2! substituted. 1

0

No difference in  Important PV production Values would be ca. 20% higher for production in China

to choose reasonable substitute!

Crystalline Si

mc-Si


Ribbon-Si

Amorpous Si

Cd-Te

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A glimpse beyond energy

Payback of greenhouse gasses emitted

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Examples electricity generated [kWh/m2] GWP System (kg CO2-eq/m2) Central Europe South Europe Crystalline Si

280

3530

6000

mc-Si

200

3295

5600

Ribbon-Si

150

2940

5000

Cd-Te

80

2235

4500

Amorpous Si

100

2650

3800

Exemplary values in reasonable range for PV system produced in Europe. GWP of substituted electricity from ecoinvent v2.2 H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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CO2 payback time [years]

Examples

160 140

Differences in electricity generated and substituted. Value

120 100 80 60

choice introduces ambiguity. Differences up to two orders of magnitude! 40

20

0

No difference in PV production

 Important to choose reasonable substitute! Crystalline Si

mc-Si


Ribbon-Si

Amorpous Si

Cd-Te

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CO2 payback time [years]

Examples

20

18

Differences in electricity generated and substituted. No difference in PV production

16 14 12 10 8 6 4 2 0

Crystalline Si

mc-Si


Ribbon-Si

Amorpous Si

Cd-Te

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Example: Influence of production location 300%

GWP Assumption: GWP of PV system produced in China is 1.5 times the GWP of the same system produced in Europe.

250% 200%

150% 100% 50% 0% Electricity, Europe Electricity, China


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Examples electricity generated [kWh/m2] GWP System (kg CO2-eq/m2) Central Europe South Europe Crystalline Si

420

3530

6000

mc-Si

300

3295

5600

Ribbon-Si

225

2940

5000

Cd-Te

150

2235

4500

Amorpous Si

120

2650

3800

Exemplary values in reasonable range for PV system produced in China. GWP of substituted electricity from ecoinvent v2.2 H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

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CO2 payback time [years] if PV system produced in China

Examples Differences in electricity generated and substituted.

30 25 20 15 10 5 0

No difference in PV production

Crystalline Si

mc-Si


Ribbon-Si

Amorpous Si

Cd-Te

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Emissions from scale up of PV What happens if PV electricity generation in Switzerland is scaled from today 0.33 to 11 TWh in 2050?

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Scale-up Worst case Assumptions: - C-Si - Production in CN - Constant properties (efficiency, GHG intensity)

GHG emitted by expansion of PV to 11 TWh in 2050 in Switzerland

t/a 100'000

GHG emitted / year [t/a]

kg/kWh

GHG emitted per kWh PV electricity

0.1

90'000

0.09

80'000

0.08

70'000

0.07

60'000

0.06

1 ‰ of Swiss emission 2011

50'000 40'000

0.05

0.04

30'000

0.03

20'000

0.02

10'000

0.01

0

0 2010

2015

2020

2025


2030

2035

2040

2045

2050

2055

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Conclusions

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Conclusions • EPBT calculation is value based. • Care has to be taken when comparing EPBT values of different studies. • Influence of (arbitrary) choices can be larger then differences between PV technologies.

• GHG payback can be much longer then EPBT • Influence of value choices on GHG payback is much bigger than on EPBT • GHG emissions from transition towards high solar share in electricity generation are comparably small.


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Contact us quantis-intl.com @Quantis Quantis glaTec Überlandstr. 129 8600 Dübendorf Tel. +41 78 7499741 H.J. Althaus, Swiss Photonics Workshop, Dübendorf 22nd 2013

Quantis Quantis International

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Allocation: cut off Bauxite

Alu

Sheet rolling

Aluminium sheet

Door production

New scrap to recycling

Vehicle door

3 products Use phase

Deconstruction

System boundary


Old scrap to recycling Old scrap to disposal Landfill

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What is “right” and why?

Allocation Bauxite

Alu

Sheet rolling

Aluminium sheet

Door production Vehicle door Use phase

Deconstruction

System boundary



Mass

•New scrap:10% •Car part: 0% 3 products •Old scrap: 90% Old scrap to recycling Old scrap to disposal

Value •New scrap:3% •Car part: 95% •Old scrap: 2%

Landfill

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Sheet rolling

Aluminium sheet

Door production Vehicle door


products product 321products

Use phase

Deconstruction

System boundary

Old scrap to recycling

Aluminium

Alu

Aluminium casting

Bauxite

Aluminium melting

Avoided allocation

Scrap preparation

Old scrap to disposal Landfill


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What energy is substituted by PV electricity?


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