Energy Emergency and New Materials

Lei Zhang & Yanli Ding

04/19/23

Energy Use

Household Energy Consumption Energy Consumption by sector and region

Source: US Energy Information Adminastration

04/19/23

US Energy Consumption 2008

Source: US Energy Information Adminastration, 2008

China Energy Consumption 2008“Coal production ramp up from 645.9 million tons of oil equivalent in 1999 to 1.552 billion tons in 2009” …… “but the country was still forced to increase coal imports by 42% in order to meet demand”

China Daily

Source: US Energy Information Adminastration, 2008

5

Fossil Fuel Consumption Climbing

Source: solarnavigator.net

04/19/23

Expanding Population

7

The Hidden Cost of Fossil Fuels

According to US Energy Information Adminastration(EIA), “Energy consumption grows by 53 percent from 2008 to 2035”

“Oil prices rose in 2010 as a result of growing demand associated with signs of economic recovery and a lack of a sufficient supply response.”

04/19/23

Greenhouse

Source: US Energy Information Adminastration

More than CO2..

Air pollutant effects• Particulates PM10 particles: particles of 10 micrometers or

less, cause heart disease, lung cancer, asthma, and respiratory infections.

• Sulfur Dioxide• Nitrogen Oxides• Ozone

04/19/23

The Hidden Cost of Fossil Fuels: Pollutants

• Particulates• Sulfur Dioxide: acid rain damage ecosystems,

historical buildings and materials (corrosion)• Nitrogen Oxides• Ozone

04/19/23

Outdoor air pollution kills 1.3 million each year

Source: World Health Organization(2010)

12

Mapping air pollution using corn grown in US fields

Source: Geophysical Research Letters.(2007)

Rhett Allain,Southeastern Louisiana University

GeothermalSolar

HydroelectricWind

Renewable Energy

Nuclear Fission

Solar Energy

• Energy produced by the sun• Clean, renewable source of energy• Harnessed by solar collection methods such as solar

cells• Converted into usable energy such as electricity• Consumes no fuel• Wide power-handling capabilities• High power-to-weight ratio• It's time to go solar!

Energy from the Sun is Abundant

Source: http://www.ez2c.de/ml/solar_land_area/

• kdlai

Solar cells would need to cover an area comparable to the size of Texas to meet US energy demand today

How does solar cell work?

• It's time to go solar!

Solar Energy Spectrum

Power reaching earth 1.37 KW/m2

Absorption of Light

• Electrons can jump between “bands”

• Incident light with energy ≥ than the “band gap” energy can be used to excite the electrons

http://www.3dchem.com/molecules.asp?ID=135#

Crystalline Silicon

• monocrystalline silicon (c-Si):

• polycrystalline silicon, or multicrystalline silicon, (poly-Si or mc-Si)

• ribbon silicon

Polycrystalline silicon wafer

• Light with energy greater than the band gap energy of Si is absorbed

• Energy is given to an electron in the crystal lattice

• The energy excites the electron; it is free to move

• A positive “hole” is left in the electron’s place

• This separation of electrons and holes creates a voltage and a current

Source: http://nanosense.org/activities/cleanenergy/solarcellanimation.html

• Expensive– Made in high vacuum at high heat– High manufacturing costs

• Need TLC– Fragile, rigid, thick

• Long return on investment– Takes 4 years to produce energy savings

equivalent to cost of production

Thin Films

• Produced from cheaper polycrystalline materials and glass

• High optical absorption coefficients• Bandgap suited to solar spectrum

CdTe/CdS Solar Cell

• CdTe: Bandgap 1.5 eV; Absorption coefficient 10 times that of Si

• CdS: Bandgap 2.5 eV; Acts as window layer• Limitation: Poor contact quality with p-CdTe (~ 0.1 cm2)

Dye-Sensitized Solar Cells

• Light with high enough energy excites electrons in dye molecules

• Excited electrons infused into semiconducting TiO2, transported out of cell

• Positive “holes” left in dye molecules

• Separation of excited electrons and “holes” creates a voltage

Source: http://nanosense.org/activities/cleanenergy/solarcellanimation.html

• Relatively inexpensive– Made in non-vacuum setting mainly at room

temperature– Relatively simple manufacturing process

• Need little TLC– Thin, lightweight, flexible

• Short return on investment– Takes approx 3 months to produce energy savings

equivalent to cost of production