1. Power Units: The Terawatt Challenge
1 W kW MW GW TW
Power

2. Current Benchmarks 500 Quad (annual total) 15 TW (average rate)
global energy usage
500 Quad (annual total)
15 TW (average rate)
- will double by 2050
carbon emissions
7 Gtons (annual total)
atmospheric CO2 level
350 ppm
280 ppm = historical background

3. Photovoltaic Land Area Requirements
3 TW
= approx total energy
currently
used in U.S.
20 TW
= minimum
carbon-free
total energy
needed by 2050
3 TW
20 TW
Graphic from
Nate Lewis
Caltech

4. Potential Energy Resources
Fossil fuels
with carbon sequestration
annual volume (STP) = Lake Superior
Nuclear
three 1 GW plants every day all year = 1 TW
Renewables
Geothermal ( ~ 12 TW )
Wind ( ~ TW )
Hydroelectric ( ~ 0.5 TW )
Solar ( ~ 120,000 TW global average)
( at least 600 TW readily available)
Basic Research Needs for Solar Energy Utilization, DOE Report, 2005 4

5. Photosynthesis
( 1961 Nobel Prize )

6. Photosynthetic Reaction Center
( 1988 Nobel Prize )

7. Artificial Photosynthesis
Any solar energy conversion method that uses some aspects of nature’s strategy, compounds, or both
Strategy
Photoinduced electron transfer across a membrane
Compounds
Chlorophyll dyes and electron-transfer mediators

8. Dye-Sensitized (Grätzel) Cell
Solar Cells
Silicon p/n Junction
Dye-Sensitized (Grätzel) Cell • e- • e-
light
absorption
charge separation
(holes and electrons) hn hn h+ h+ o o
n-Si
p-Si
ETM
dye
HTM

9. Polyaniline

10. Poly-TAPP
Oxidative electropolymerization of TAPP is expected to occur like aniline polymerization
Covalent links could include simple amines or cyclization to phenazine bridge

11. Polymers of TAPP Poly-TAPP is electrically conductive
and has a fibrous structure with a
very high surface area
Poly-TAPP generated without pyridine
catalyst has higher conductivity and
a slightly different morphology