Power Units: The Terawatt ChallengePower Units: The Terawatt Challenge

PowerPower11 101033 10 1066 10 1099 10 101212

1 W 1 kW 1 MW 1 GW 1 TW1 W 1 kW 1 MW 1 GW 1 TW

Current BenchmarksCurrent Benchmarks• global energy usageglobal energy usage

500 Quad 500 Quad (annual total)(annual total)

15 TW 15 TW (average rate)(average rate)

- will double by 2050- will double by 2050• carbon emissionscarbon emissions

7 Gtons 7 Gtons (annual total)(annual total)

• atmospheric COatmospheric CO22 level level

350 ppm 350 ppm 280 ppm = historical background280 ppm = historical background

Photovoltaic Land Area RequirementsPhotovoltaic Land Area Requirements

20 TW

3 TW

Graphic fromNate LewisCaltech

3 TW= approx

total energycurrently

used in U.S.

20 TW= minimum carbon-freetotal energyneeded by

2050

Potential Energy ResourcesPotential Energy Resources Fossil fuelsFossil fuels

with carbon sequestrationwith carbon sequestration annual volume (STP) = Lake Superiorannual volume (STP) = Lake Superior

NuclearNuclear three 1 GW plants every day all year = 1 TWthree 1 GW plants every day all year = 1 TW

RenewablesRenewables Geothermal ( ~ 12 TW )Geothermal ( ~ 12 TW ) Wind Wind ( ~ 2 - 4 TW )( ~ 2 - 4 TW ) Hydroelectric ( ~ 0.5 TW )Hydroelectric ( ~ 0.5 TW ) Solar Solar ( ~ 120,000 TW global average)( ~ 120,000 TW global average)

( at least 600 TW readily available)( at least 600 TW readily available)

Basic Research Needs for Solar Energy UtilizationBasic Research Needs for Solar Energy Utilization, DOE Report, 2005, DOE Report, 2005

PhotosynthesisPhotosynthesis( 1961 Nobel Prize )( 1961 Nobel Prize )

Photosynthetic Reaction CenterPhotosynthetic Reaction Center

http://www.mpibp-frankfurt.mpg.de/~michael.hutter/rcenter.html

( 1988 Nobel Prize )( 1988 Nobel Prize )

Artificial PhotosynthesisArtificial Photosynthesis

Any solar energy conversion method that uses some aspects of nature’s strategy, compounds, or both

StrategyPhotoinduced Photoinduced

electron transfer electron transfer across a membraneacross a membrane

CompoundsChlorophyll dyes Chlorophyll dyes

and electron-and electron-transfer mediatorstransfer mediators

Solar CellsSolar Cells

e-

h+

ETM HTMdye

Dye-Sensitized (Grätzel) CellDye-Sensitized (Grätzel) CellSilicon p/n JunctionSilicon p/n Junction

hh

e-

h+

n-Si p-Si

• •

oo

hh

•light absorption

• charge separation (holes and electrons)

PolyanilinePolyaniline

N

H

N

H

N

N

H

N

HH

n

N

H

N

H

N

N

H

N

HH

n

N

H

N

N

NN

HH

N

H

N

H

N

N

H

N

HH

n

n

- 2 H +

- 2 e -

- 2 e -

leucoemeraldine(colorless, nonconductive)

pernigraniline(black, nonconductive)

emeraldine base(blue, nonconductive)

emeraldine (green, conductive)

Poly-TAPPPoly-TAPP

• Oxidative electropolymerization of TAPP is Oxidative electropolymerization of TAPP is expected to occur like aniline polymerizationexpected to occur like aniline polymerization

• Covalent links could include simple amines or Covalent links could include simple amines or cyclization to phenazine bridgecyclization to phenazine bridge

Polymers of TAPPPolymers of TAPP

Poly-TAPP is electrically conductiveand has a fibrous structure with avery high surface area

Poly-TAPP generated without pyridinecatalyst has higher conductivity anda slightly different morphology