Solar Energy Workshop Alexis Ostrowski and Bright Walker Sponsored by ConvEne-IGERT at UCSB

It’s true: The kinetic energy of planets causes them to orbit the sun. Energy Makes the World Go Round

Energy Cannot be Created or Destroyed Energy is constantly changing from one form to another. Nuclear Electromagnetic Thermal Kinetic Chemical

How We Use and Control Energy Nuclear Reactor Fire Chemical energy Thermal Energy Nuclear energy Thermal Energy

Where Do We Get Energy From? ? ? ? Sources: CoalHydroelectric (Dams) WindSolar NuclearGasoline Natural Gas

Oil (37%) Natural Gas (23%) Coal (25%) Nuclear (6%) Biomass (wood, 4%) Water (dams, 3%) Other (solar, wind, geothermal, <2%) Over 85% of our energy comes from fossil fuels Global Energy Usage

Fossil Fuels and Climate Change CO 2 Greenhouse gasses Burning fossil fuels releases CO 2 and other greenhouse gasses into the air CO 2 helps warm up the earth’s atmosphere This changes the earth’s weather patterns (polar ice melting) Polar ice coverage

Fossil Fuels Fossil fuels are not renewable--it takes millions of years to form them Fossil Fuels are made by millions of years of pressure and heat that turns dead plants and animals (fossils) into crude oil and coal

Renewable Energy Renewable sources of energy will never run out. Wind Geothermal Solar Water Biomass

WIND Kinetic energy electricity e-e-

WATER Kinetic energy electricity e-e-

BIOFUELS Chemical energy kinetic energy

GEOTHERMAL Thermal energy Electricity e-e-

SOLAR Light energy electricity e-e-

Cost of Renewable Energy It costs more to produce renewable energy than it does to collect fossil fuels. We need to research new ways to make renewable energy more affordable! Silicon solar cells are very expensive to manufacture.

Energy research at UCSB Light emitting diodes (LEDs) - To produce light using a minimum amount of energy Solar cells -Direct conversion of sunlight into electricity

Solar Cells Direct conversion of solar energy into electricity! Clean Renewable Abundant Easy to use Light goes in Semiconductor material Electricity comes out Many types: Inorganic (Silicon)$$$ Organic/Plastic (Bucky balls) COOL!! Electrodes

Inorganic Solar Cells P doped region, consisting of stationary, negative Boron impurities and mobile positive charges called holes Intrinsic, undoped region N doped region, consisting of stationary, positive Phosophorus impurities and mobile negative charges called electrons This assembly is collectively called a “PIN junction”. P I N

Inorganic Solar Cells As soon as the junction is created, some of the mobile holes combine with the mobile electrons. This leaves behind excess positive and negative charges in the doped regions, creating a strong electric field within the crystal Electric Field Electrons and holes are free to move around.

Inorganic Solar Cells Electric Field Anode Cathode Electrodes are applied to the PIN junction. Absorption of light can cause the spontaneous generation of an electron-hole pair. The elcectric field within the device causes the charges to move in opposite directions. This movement of charges creates a useable current at the anode and cathode.

Plastic Solar Cells Transparent Electrode Aluminum 1)Light Absorption 2)Exciton Diffusion 3)Charge Separation 4)Charge Transport Positive and negative molecules mixed together between electrodes. -Like a Spaghetti and Meatball Sandwich

Plastic Solar Cells Apply Electrodes Plastic solar cells are made out of materials very similar to ink. They are very easy to make!

Plastic Solar Cells Low cost, low energy fabrication! Large area potential! Efficiency, stability lower than inorganic solar cells Still a long way to go before having a big impact on overall energy problems Nobel Lauriat Prof. Alan Heeger, enjoying his invention Roll to roll printer

What you can do… Use less energy 15 kWh/d 5 kWh/d 40 kWh/d 20 kWh/d 40 kWh/d 5 kWh/d Before:After: What you Can do Food Heating Transportation Eat vegetarian 6 days/wk Put on a sweater Carpool, walk, bike, or take the bus 3 simple things that make a difference (avg 30 miles/day) Skate or take a bus to school!

Summary Solar Energy is a promising source of renewable energy We need more efficient (and cheaper) solar cells UCSB researchers are working hard to develop new technologies that solve energy problems Plastic solar cells are a new technology that are cheaper and easier to make than silicon solar cells You can help with the energy problem by using less energy You can also become a scientist and help discover new solutions to our energy problems

Lets build a solar car! Photo by Bright Walker