优秀学术报告PPT示例(物理学家Chen Gang)

300
280 260 240
- 1.0
- 1.5
Intergovernmental Panel on Climate Change, 2001
http://www.ipcc.ch
1000
1200
1600 1400 Year AD
1800
2000
The Energy Source Challenge
Energy demand and GDP per capita (1980-2002) Primary energy per capita (GJ)
2000: 13 TW 2050: 30 TW 2100: 46 TW
(Hoffert et al Nature 395, 883,1998)
GDP per capita (purchasing power parity)
2.5
• •
Low materials cost and low capital cost, potentially high efficiency. Key Challenges: Develop materials with high thermoelectric figure of merit; and selective surfaces that absorb solar radiation but do not re-radiative heat.
Oceana Oceania N. America Europe S. America Africa
2005
6.5 Billion
1 2 3 4 5 6
2050
8.9 Billion
1 2 3 4 5 6
Asia Dresselhaus, APS March 2006
Asia
Growing world energy needs
(b)
0 1.5 0 5 10 15
(c) Selective Emitter
1.0 0.5
0
0
Wavelength (m)
(d)
2
4
6
8
10
12
Thermal Management
0
0
Wavelength (m)
2
4
6
8
10
12
• •
Theoretical maximum efficiency: 85.4%; comparable to that of infinite number of multi-junction cells, but with only a single junction PV cell. Key Challenges: Selective surfaces absorbing solar radiation but reemitting only in a narrow spectrum near the bandgap of photovoltaic cells, working at high temperatures.
0
500 400
300
- 4
- 8 380
T relative to present (°C)
-- CO2 -- CH4 -- T
+ 4
Relaxation times 50% of CO2 pulse to disappear: 50 - 200 years transport of CO2 or heat to deep ocean: 100 - 200 years
2050
30 Terawatts (world)
0.5%
0
G as
O il
Co a
m as
sio
ric
/F is
Bi o
ec t
ro
dr
ge
Fu s
H yd
Hy
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• Achieve Energy independence through renewable energy. • Find substitute for gasoline (portable high density energy) • Cost efficient technology
Gang Chen (Director) MIT: M.S. Dresselhaus, E.A. Fitzgerald, J. Joannopoulos, J.G. Kassakian, S.-G. Kim, K. A. Nelson, Y. ShaoHorn, C.A. Schuh, M. Soljacic, E.N. Wang Boston College: C.P. Opeil, Z.F. Ren Oak Ridge National Laboratory: O. Delaire, D.J. Singh
So
Source: International Energy Agency
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alLeabharlann nslThermal to Electrical Energy Conversion Technologies
Temperature (K)
COEFFICIENT OF PERFORMANCE
Thermoelectric Energy Conversion Efficiency
6
COEFFICIENT OF PERFOR MANCE
5
CARNOT C YCLE STIRLING REFRIGERATORS HOUSEHOLD REFRIGERATORS & AIR-CONDITIONERS THERMOELECTRIC REFRIGERATORS
Bandgap of Silicon (1.1 m)
1 1.5 2 Wavelength (m)
2.5
3
Solar Thermophotovoltaics
Power (W/m2m)
1500 1000 500 0 0
Solar Insolation
Optical Concentrator Wavelength (m)
4
3
2
0.5
1
1
24
ZT m 10 7
STIRLING CRYOCOOLERS
TPV
0
1
1.2 1.4 1.6 TEMPERATURE RATIO (T
hot
1.8 2.0 /T )
cold
Nanoscale Effects for Thermoelectrics
Interfaces that Scatter Phonons but not Electrons
50 45 40 35 30 25 20 15 10 5 0
al c io n al s s l tri Oi m Ga as Co om he r lec ss Fi oe ot Bi
2003
50 45 40 35 30 25 20 15 10 5
2050
TODAY
14 Terawatts (world)
A Proposal Submitted to Department of Energy’s Call for Energy Frontier Research Centers
Solid-State Solar-Thermal Energy Conversion Center (S3TEC Center)
0 10 8 6 4
50 100 150 200 250 300500
1000
1500
2000 5000 2500
5500
6000 1
0.8
REFRIGERATION
POWER GENERATION
EFFICIENCY
Household Refrigerator Thermoelectrics ThermoPV
Reverse Heat Leakage Through Heat Conduction
MISSION OF S3TEC CENTER
▪ thin film ▪ nano-bulk ▪ characterization ▪ devices ▪ solar TPV & TE ▪ low cost approach
THERMOELECTRIC DEVICES
COLD SIDE
COLD SIDE
-
+
I
HOT SIDE
N
P
HOT SIDE
Nondimensional Figure of Merit
Joule Heating Seebeck Coeff.
S2T ZT k
GPHS Radioisotope Thermoelectric Generator
Solar Spectrum
1800
Terrestrial Solar Spectrum (W/m2m)
1600 1400 1200 1000 800 600 400 200 0 0 0.5
AM1.5 Solar Spectrum Energy Usable for Silicon PV Cells
• Metamaterial • Coherent emission • Blackbody limit?
• 0 Lorenz number • Coherent scattering • Mobility engineering • Spectroscopy • Interface engineering • Lower Limit?