John Bowers

bowers@iee.ucsb.edu

iee.ucsb.edu

IEE Activities

New Materials for Thermoelectrics for

Refrigeration, Power Generation

and Waste Heat Recovery

Institute for Energy Efficiency

Innovating Global Energy Solutions

UC Santa Barbara

• Dynamics of Energy Efficiency (Buildings)

• Computing and

Networks

• Production and Storage

• Lighting and Displays

• Policy and

Economics

• Mark Manydosa, Minister of Tanzania, spoke of the need for improved

efficiency in irrigation systems.

• 400,000 hectares of irrigation needed for self sufficiency.

• Unaccounted usage was 50% in 2000, now 30%.

• The need for more efficient irrigation systems requires

– Sensors to determine hydration of soil

– Sensors to determine wafer flow, availability, and losses

– Actuators to adjust flows

– Ad hoc network between sensors, actuators and a global control and

monitoring center

– An autonomous decision making system

• Mark Manydosa, Minister of Tanzania spoke of the need for improved

efficiency in irrigation systems.

• The need for more efficient irrigation systems requires

– Sensors to determine hydration of soil

– Sensors to determine wafer flow, availability, and losses

– Actuators to adjust flows

– Ad hoc network between sensors, actuators and a global control and

monitoring center

– An autonomous decision making system

• This is similar to the requirements of more efficient buildings where one

wants to control lights or airflow.

• Where does cooled air flow, or how much and when. Sensors, actuators

and communication.

• One can build a network of solar powered sensors and actuators that

wirelessly communicate with each other and with a centralized controller,

with an intelligent program for optimization and control.

• Mark Manydosa, Minister of Tanzania spoke of the need for improved

efficiency in irrigation systems.

• The need for more efficient irrigation systems requires

– Sensors to determine hydration of soil

– Sensors to determine wafer flow, availability, and losses

– Actuators to adjust flows

– Ad hoc network between sensors, actuators and a global control and

monitoring center

– An autonomous decision making system

• This is similar to the requirements of more efficient buildings where one

wants to control lights or airflow.

• Where does cooled air flow, or how much and when. Sensors, actuators

and communication.

One can build a network of solar powered sensors and actuators that

wirelessly communicate with each other and with a centralized

controller, with an intelligent program for optimization and control.

• Dynamics of Energy

Efficiency

• Computing and

Networks

• Production and Storage

• Lighting and Displays

• Policy and

Economics

• A common problem in

developing countries is

burning kerosene for

lighting.

• This is expensive, polluting,

and hazardous to the user’s

health.

• A number of organizations

are addressing this need:

LUTW, BOGO,…

Dave Irvine-Halliday, founder of Light

Up The World, with two kerosene wick

lamps, previously the main source of

illumination in the village

• IEE is partnering with Engineers without

Borders, and Pangea to get low cost, high

quality solar powered lighting to people in

Ghana.

• Combines:

– Efficient, low cost, long lifetime LEDs

– Efficient, low cost, long lifetime batteries

– Efficient, low cost, long lifetime solar cells

• Efficient lighting for <$10. Pays for itself in 2 months.

• Dynamics of Energy

Efficiency

• Computing and

Networks

• Production and Storage

• Lighting and Displays

• Policy and

Economics

• Eliminate conventional refrigerators

• Eliminate need for refrigerants (CFCs and replacement gasses)

• Reduce energy consumption.

• Improve efficiency in solid state refrigerators.

. • A solid state thermoelectric refrigerator

could be 10 times smaller than a

conventional refrigerator.

• Longer Lifetime

• A typical refrigerator is replaced every 15 years.

• Solid state refrigerators should last 50 years.

Automotive ApplicationsHeating, cooling, waste heat recovery,

replace generator, replace internal

combustion engine (ZT>4 required).

Impact: Thermoelectrics

Relative

Efficiency

0.1

0.4

0.3

0.2

ZT

1 2 3 4

Commercial TE’s

Typical mechanical systems

ZT is a metric related to efficiency.

ZT~1 is common today.

Increasing ZT to 4 enables efficient solid

state refrigerators, efficient air

conditioning and efficient, cost effective

waste heat recovery.

Hot and cold

electrons in

equilibrium

Hot

electron

filter

0

1

2

3

4

5

6

7

8

-1

0

1

2

3

4

5

0 2 4 6 8 10 12 14

barrie

rf

B

Fermi Energy (eV)

Conserved

Non-conserved

New Concept to Optimize TE Efficiency:New Concept to Optimize TE Efficiency:(Metal/Semiconductor Nanocomposites) (Metal/Semiconductor Nanocomposites)

Even with only modestly low lattice thermal conductivity and

electron mobility of typical metals, ZT > 5 is theoretically possible

with hot electron filters

EEEEEEEEEEEEEEEEEEEEEEEEEE

ErAs nanocrystals in InGaAlAs

Many other Lanthanide elements are possible.

Power generator module fabrication:

EEEEEEEEEEEEEEEEEEµµµµEEmEEEEµµµµE

AAAAAEEEEEEEEEEEEEEEEmEEEEAAEEEEEEEEEEEAEEEAEEEEmEAEEE

Waste Heat Recovery or Power Generation are also possible.

(Run the refrigerator in reverse: Put in heat and take out electricity)

2015 Technology Initiatives

Zero-Net Energy Buildings and Homes

Lighting - 300Lm/W LED at the cost of a regular light bulb

Solar Cells: Double the efficiency at one-tenth the cost

1000x Faster Computing/Watt

Thought Leadership Initiatives

Distinguished Fellows Program

International Conferences

IEE INITIATIVES