Nathan S. Lewis

George L. Argyros Professor of Chemistry

California Institute of Technology

with

George Crabtree, Argonne NLArthur Nozik, NREL

Mike Wasielewski, NorthwesternPaul 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 UtilizationReport of the Basic Energy Sciences Workshop on Solar Energy Utilization

Solar Energy Utilization

Solar ElectricSolar Fuel

Solar Thermal

.001 TW PV$0.30/kWh w/o storage

CO2

sugar

naturalphotosynthesis

50 - 200 °Cspace, water

heating

500 - 3000 °Cheat engines

electricity generationprocess 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 waterheating

H2O

O2

Solar Energy Costs

competitive electric power: $1.00/Wp = $0.05/kWh

competitive primary power: $0.20/Wp = $0.01/kWh including cost for storage

Cost $/m2

$0.10/Wp $0.20/Wp $0.50/Wp

Effi

cie

ncy

%

20

40

60

80

100

100 200 300 400 500

$1.00/Wp

$3.50/Wp

module cost onlydouble for balance of system

$0.25-0.50/kW-hr

Solar Energy Conversion

Conversion

e-

h+

Storage

Capture

100 nm-100 µm

“Solar Paint”

inexpensive processing, conformal layers

polymer donorMDMO-PPV

fullerene acceptorPCBM

O

O

()n

OOMe

OOMe

d

“Fooling “inexpensive particles into behaving as single crystals

Interpenetrating Nanostructured Networks

-

metal electrode

transparent electrode

glass

+- 100 nm

---

metal electrode

transparent electrode

glass

+- 100 nm

Ultra-high Efficiency Solar Cells

multiple junctions

hot carriers

3 V

rich variety of new physical phenomenaunderstand and implement

lost toheat

Substrate

Metal

H2 Purification, Storage,

Dispensing

H2 Production

Fuel

Cell

Stationary Generation

Fuel Processor

or Electrolyzer

Fuel Cell

H2

Reformate H2 /

Storage: The Need to Produce Fuel

“Power Park Concept”

Fuel Production

Distribution

Storage

Solar Thermal + Electrolyzer System

Solar-Powered Catalysts for Fuel Formation

hydrogenase

2H+ + 2e- H2

10 µ

chlamydomonas moewusii

2 H2O

O2

4e-

4H+

CO2

HCOOHCH3OHH2, CH4

Cat Cat

oxidation reduction

photosystem II

Solar Land Area Requirements

3 TW

Control of Materials Properties Through Nanoscience

biological physical

demonstrated efficiencies 10-18% in laboratory

+

-

H2O2

Self-assembly of complex structures

Hydrogen from water and sunlight

mechanical

Nanoscience and Solar Energy

N

theory and modelingmulti-node computer clusters

density functional theory10 000 atom assemblies

manipulation of photons, electrons, and molecules

quantum dot solar cells

artificialphotosynthesi

s

naturalphotosynthesi

snanostructuredthermoelectrics

nanoscale architecturestop down lithography

bottom up self-assemblymulti-scale integration

characterizationscanning probes

electrons, neutrons, x-rayssmaller length and time scales

Solar energy is interdisciplinary nanoscience

TiO2 nanocrystals

adsorbeddye

liquidelectrolyteco

nd

uct

ing

gla

ss

tran

spare

nt

ele

ctro

de

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 technologywill 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