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RENEWABLE ENERGYRENEWABLE ENERGY
What it is What it is
&&
What it isn’tWhat it isn’t
Vocab Buzz
• Sustainable
• Renewable
• NonRenewable
• Organic
• Green
• Clean
Energy Waste & InefficiencyWhat’s the moral of this
story?• Conservation vs.
Efficiency
• 84% of commercial energy in US is wasted– 41% due to entropy
(2nd law of thermo)
– 43% unnecessary; inefficiency
• $570,000/min
How does energy get wasted?
• Net Energy Yield• Net Energy EfficiencyNet Energy Efficiency
– Combine efficiencies of all steps in energy conversion for the entire system
Every hour the sun beams onto Earth more than enough energy to satisfy global energy needs for an entire year.
Solar Energy
Passive Solar Heating and Cooling
How does it work?
Passive Solar Heating
http://www.livingonsolar.com/passive-solar-video.html
Passive Solar Heating
Passive Solar Heating
• ADVANTAGES
– HIGH net energy yield
– Free energy
– No pollutants
– Moderate cost
• DISADVANTAGES
– Is there enough available sunlight in all areas?
• Need 60% of the time• Needs correct
orientation
– Need heat storage or backup
Solar Cooling• Super-insulation• Block summer sun trees, awning, etc.• Good ventilation• Earth Tubes
– Soil ~5-13ºC– Moves cool, dry air in– Inexpensive
• Light colored roof• Reflective foil in attic• Earth sheltered building
Active Solar Heating
•Solar collectors on roof
•Heat stored in insulated tanks of water, rocks, heat-absorbing chemical
•Used for heating and hot water
Active Solar
• ADVANTAGES
– No pollutants
– Moderate net energy
– Free after initial installation
• DISADVANTAGES
– Unattractive
– Is there enough available sunlight in all areas?
• Needs correct orientation
– Requires a backup hot water source
– Pump requires energy, maintenance
Solar cooker
Solar Thermal Plant
Parabolic (U-shaped mirrors) concentrate the sun’s rays onto a black pipe containing molten salts or oil.
This produces steam to turn a turbine and generator.
Pros and Cons
PROS
• Non-polluting, no carbon emissions
• High efficiency (~15%)• Operating costs are low
CONS
• Takes up a lot of land – 1 sq. mile or more
• Not always reliable• Slightly more expensive
than PV cells• New technology involved• Heavily location
dependent
Why do we waste so much?• Fossil fuels cheap• Few gov’t
incentives• Inaccurate pricing• Inequitable
subsidies• What are the
benefits to reducing?
Photovoltaic Cells
1. Sunlight strikes semi-conductor
2. Electrons move
3. Energy can be stored in battery
• Life is carbon-based for a reason
• Silicon atoms have the same capabilities
http://www.youtube.com/watch?v=K76r41jaGJg(1:07 mins)
Solar Cells
• ADVANTAGES
– No pollutants
– Safe
• DISADVANTAGES
– Expen$ive!
– Need large surface area
– Unattractive
– Is there enough available sunlight in all areas?
– Requires a backup electricity source
Hydrogen Fuel Cells
• How it Works:– Combines H with O to
produce energy
– Can be fueled by anything with H in it
• Natural gas, alcohol, gas
– Gives off water
http://www.pbs.org/wgbh/nova/sciencenow/3210/01.html(12:49 mins)
Hydrogen Fuel Cells
• ADVANTAGES
– H is abundant
– Non polluting
• DISADVANTAGES
– Not very efficient to produce
• Takes electricity to split water and produce H
– Expensive
– Needs to be stored at high pressure
Energy Types:Can you match and discuss the +/- ?
• Chemical• Electrical• Mechanical• Light (EM)• Nuclear• Heat
• Clean• Renewable• Sustainable
• Wind• Hydrothermal• Active Solar• Biomass• Passive Solar• Coal, Oil, Natural Gas• Hydrogen Fuel Cells• Hydroelectric• Tidal
Slide Bank
Use renewable energy!
• Benefits of shifting to local, renewable energy sources– More reliable source– Improve national security– Reduce trade deficits due to importing oil– Reduce greenhouse gases and other air pollution– Creates jobs– Saves $ in the long run
Hybrid, Plug-in hybrid, Electric
• Hybrid Car Flash Animation– Prius Hybrid Synergy Drive
• GM Volt (2010)– http://gm-volt.com/about/– http://www.chevrolet.com/electriccar/
• The EV-1– http://ev1-club.power.net/
• The Tesla– http://www.teslamotors.com/
• http://www.fueleconomy.gov/feg/• http://www.nrel.gov/vehiclesandfuels/hev/
More on Batteries
• Carbon-Zinc – 1st Duracell
• Lead-Acid – Car batteries
• Nickel Cadmium – consumer electronics
• Nickel-Metal Hydride
• Lithium Ion – notebook computers
• Lithium polymer – newest development
3 types of Heat Transfer
TRADE-OFFS
Passive or Active Solar Heating
Advantages Disadvantages
Energy is free Need access to sun 60% of time
Net energy is moderate (active) to high (passive)
Sun can be blocked by trees and other structures
Quick installation Environmental costs not included in market priceNo CO2 emissions
Very low air and water pollution
Need heat storage system
Very low land disturbance (built into roof or windows)
Active system needs maintenance and repair
High cost (active)
Active collectors unattractive
Moderate cost (passive)
What IS a Battery?
• Energy Storage System!
• As easy as a clock spring or a log
• Is that potential or kinetic?
What IS a Battery? -aka cell
• Changes chemical energy to electrical
• Voltaic cells (cells that can transfer voltage)
• Electrons collect on the negative terminal of the battery
• Flows between the positive and negative terminals if a conductor (or wire) is present
http://www.howstuffworks.com/battery.htmBattery video
What is Energy?
• “The Ability to do Work”
The world is made up of MATTER & ENERGY.– Which one cycles and which one flows?
• The 2 classes are Potential & Kinetic• The 6 types are:
– Chemical, Mechanical, Nuclear, Light (EM), Heat, Electrical
Where are we now?
Coal Gasification
Where might we go?
Hydrogen Fuel Cells
What’s the bridge to get there?
Photovoltaic Cells
