1. Nathan S. Lewis George L. Argyros Professor of Chemistry California Institute of Technology with George Crabtree, Argonne NL Arthur Nozik, NREL Mike Wasielewski, Northwestern Paul Alivisatos, UC-Berkeley Solar Energy and Nanotechnology Based on : Basic Research Needs for Solar Energy Utilization: Report of the Basic Energy Sciences Workshop on Solar Energy Utilization

2. Solar Energy Utilization Solar Electric Solar Fuel Solar Thermal.001 TW PV $0.30/kWh w/o storage CO 2 sugar natural photosynthesis 50 - 200 °C space, water heating 500 - 3000 °C heat engines electricity generation process heat 1.5 TW electricity $0.03-$0.06/kWh (fossil) 1.4 TW solar fuel (biomass) ~ 14 TW additional energy by 2050 0.002 TW 11 TW fossil fuel (present use) 2 TW space and water heating H2OH2O O2O2

3. Solar Energy Costs competitive electric power: $1.00/W p = $0.05/kWh competitive primary power: $0.20/W p = $0.01/kWh including cost for storage Cost $/m 2 $0.10/W p $0.20/W p $0.50/W p Efficiency % 20 40 60 80 100 200 300 400 500 $1.00/W p $3.50/W p module cost only double for balance of system $0.25-0.50/kW-hr

4. Solar Energy Conversion Conversion e-e- h+h+ Storage Capture 100 nm-100 µm

5. “Solar Paint” inexpensive processing, conformal layers polymer donor MDMO-PPV fullerene acceptor PCBM O O ( ) n d “Fooling “inexpensive particles into behaving as single crystals

6. Interpenetrating Nanostructured Networks

7. Ultra-high Efficiency Solar Cells multiple junctions hot carriers 3 V rich variety of new physical phenomena understand and implement lost to heat Substrate Metal

8. Storage: The Need to Produce Fuel “Power Park Concept” Fuel Production Distribution Storage

9. Solar Thermal + Electrolyzer System

10. Solar-Powered Catalysts for Fuel Formation hydrogenase 2H + + 2e -  H 2 10 µ chlamydomonas moewusii 2 H 2 O O2O2 4e - 4H + CO 2 HCOOH CH 3 OH H 2, CH 4 Cat oxidationreduction photosystem II

11. Solar Land Area Requirements 3 TW

12. Control of Materials Properties Through Nanoscience biologicalphysical demonstrated efficiencies 10-18% in laboratory + - H2H2 O2O2 Self-assembly of complex structures Hydrogen from water and sunlight mechanical

13. Nanoscience and Solar Energy theory and modeling multi-node computer clusters density functional theory 10 000 atom assemblies manipulation of photons, electrons, and molecules quantum dot solar cells artificial photosynthesis natural photosynthesis nanostructured thermoelectrics nanoscale architectures top down lithography bottom up self-assembly multi-scale integration characterization scanning probes electrons, neutrons, x-rays smaller length and time scales Solar energy is interdisciplinary nanoscience TiO 2 nanocrystals adsorbed dye liquid electrolyte conducting glass transparent electrode

14. Basic Research Needs for Solar Energy The Sun is a singular solution to our future energy needs - capacity dwarfs fossil, nuclear, wind... - sunlight delivers more energy in one hour than the earth uses in one year - free of greenhouse gases and pollutants - secure from geo-political constraints Enormous gap between our tiny use of solar energy and its immense potential - Incremental advances in today’s technology will not bridge the gap - Conceptual breakthroughs are needed that come only from high risk-high payoff basic research Interdisciplinary research is required physics, chemistry, biology, materials, nanoscience Basic and applied science should couple seamlessly