1

Solar Cells and LightSolar Cells and Light--Emitting Diodes:Emitting Diodes:

two optoelectronic devices for atwo optoelectronic devices for a

greener planetgreener planet

Masterclass, Institute of Advanced Studies, UWA, April 14, 2010

D.L. Pulfrey

Gledden Senior FellowUniversity of Western AustraliaFebruary – April, 2010

Department of Electrical and Computer EngineeringUniversity of British ColumbiaVancouver, B.C. V6T1Z4, Canada

http://www.ece.ubc.ca/~pulfrey/

2

Solar Cells and LightSolar Cells and Light--Emitting Diodes:Emitting Diodes:

two optoelectronic devices for atwo optoelectronic devices for a

greener planetgreener planet

1. Solar cells and LEDs: how they fit into the world’s generation-and lighting-mixes.

2. Solar cells and LEDs: their design and operation.

3. LEDs: their prospects for contributing significantly to general-purpose lighting.

4. Solar cells: their prospects for contributing significantly to sustainable electricity generation.

3

green and Greengreen and Green

green (adj.) – emphasizing environmental issues

greening (verb) - the process of transforming artifacts such as a space, a lifestyle or a brand image into a more environmentally friendly version

Green (noun) – political ideology, e.g., “Our vision is for a fair, independent and sustainable Australia.”

sustainable (adj.) – capable of enduring, e.g., “sustainable development ... meets the needs of the present without compromising the ability of future generations to meet their own needs.”*

* http://www.un-documents.net/ocf-02.htm

4

The Generation MixThe Generation Mix

Imagine 20 TkWh

Elec. use

2010 Hours/yr Elec. power

World

population Power/person

TkWh/yr kW W

20 8760 2.28E+09 6.80E+09 336

The Generation Mix (another view)The Generation Mix (another view)5

6Do we want more coalDo we want more coal--fired plants?fired plants?

7Projections for renewable sourcesProjections for renewable sources

Solar PowerSolar Power8

Solar thermal: 10 + 20 MW, SevilleSolar thermal: 10 + 20 MW, Seville9

Solar PV: 60 MW, Solar PV: 60 MW, OlmedillaOlmedilla de de AlarconAlarcon10

11PV: large and smallPV: large and small

Photos of solar cell installations

12 MW Arnstein, Germany

26 MW Tabernas desert, Spain

5kW Boston Massachusetts http://256.com/solar/

PV “balancePV “balance--ofof--system” componentssystem” components12

Also:

- installation

- wiring

- insurance

http://www1.eere.energy.gov/solar/bos.html

Electricity consumption per capitaElectricity consumption per capita13

200610,720.756 kWh per capitaAustralia:# 13

200711,718.884 kWh per capitaCayman Islands:# 12

200611,819.586 kWh per capitaBahrain:# 11

200612,483.568 kWh per capitaUnited Arab Emirates:# 10

200712,924.224 kWh per capitaUnited States:# 9

200614,604.742 kWh per capitaLuxembourg:# 8

200614,769.403 kWh per capitaSweden:# 7

200615,210.945 kWh per capitaKuwait:# 6

200615,938.943 kWh per capitaQatar:# 5

200616,279.411 kWh per capitaCanada:# 4

200716,850.372 kWh per capitaFinland:# 3

200624,011.233 kWh per capitaNorway:# 2

200631,147.292 kWh per capitaIceland:# 1

200610,720.756 kWh per capitaAustralia:# 13

200711,718.884 kWh per capitaCayman Islands:# 12

200611,819.586 kWh per capitaBahrain:# 11

200612,483.568 kWh per capitaUnited Arab Emirates:# 10

200712,924.224 kWh per capitaUnited States:# 9

200614,604.742 kWh per capitaLuxembourg:# 8

200614,769.403 kWh per capitaSweden:# 7

200615,210.945 kWh per capitaKuwait:# 6

200615,938.943 kWh per capitaQatar:# 5

200616,279.411 kWh per capitaCanada:# 4

200716,850.372 kWh per capitaFinland:# 3

200624,011.233 kWh per capitaNorway:# 2

200631,147.292 kWh per capitaIceland:# 1

http://www.nationmaster.com/graph/ene_ele_con_percap-energy-electricity-consumption-per-capita

Electricity usage by sector (USA)Electricity usage by sector (USA)14

http://www.eia.doe.gov/emeu/aer/eh/elec.html

Residential usage of electricityResidential usage of electricity15

16

Lighting: growth and costLighting: growth and cost

J.Y. Tsao http://www.sandia.gov/~jytsao/

17

How much energy is used for lighting?How much energy is used for lighting?

Compare these numbers with IEA’s.

Light bulb comparisonLight bulb comparison18

W lumens khours CRI $US

Incandescent (long life)

75 (1200) 10 (95) 1.75

W-halogen (PAR38)

75 940 5 (95) 5.95

Fluorescent(T10 tube)

40 3550 20 84 6.95

Fluorescent(compact)

20 1295 12 82 4.95

LED(PAR20, warm)

9 400 40 77 58.95

Data: 12 April, 2010: BuyLighting.com

The LED efficiency needed to save powerThe LED efficiency needed to save power19

• 2010: ??

D.A. Steigerwald et al., IEEE J. Sel. Topics Quantum Electron., 8, 310-320, 2002

Interim summaryInterim summary20

Hypotheses:

1. Photovoltaics can help green electricity generation.

2. LEDs can reduce significantly the demand for electricity.

Questions to ponder:

1. Is PV really sustainable?

2. Can LEDs meet general-lighting requirements?

3. How do solar cells and LEDs work?

4. What are the significant features of their design?