What it is & What it isn’t RENEWABLE ENERGY What it is & What it isn’t

Vocab Buzz Sustainable  Renewable  NonRenewable  Organic  Green  Clean  B: Students brainstorm and construct lists. Best answers are put on the board. Throughout class, stress that none are necessarily synonymous, although green and sustainable are likely the best pair for the energy movement.

Energy Waste & Inefficiency What’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 Look at unnecessary waste vs petrochemicals. Sure they’re nonrenewable, but stupidity is our greatest hurdle.

How does energy get wasted? Net Energy Yield Net 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. the solar energy hitting the earth exceeds the total energy consumed by humanity by a factor of over 20,000 times. How does energy get wasted?

Every hour the sun beams onto Earth more than enough energy to satisfy global energy needs for an entire year. Why is solar our best transition option?

Solar Energy

Passive Solar Heating and Cooling How does it work?

Passive Solar Heating http://www.livingonsolar.com/passive-solar-video.html

Thick walls & insulation on north side. Passive Solar Heating SOUTH FACING Venting in summer Thick walls & insulation on north side.

Passive Solar Heating ADVANTAGES DISADVANTAGES 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 Water Heating

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 DISADVANTAGES 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 CONS Non-polluting, no carbon emissions High efficiency (~15%) Operating costs are low 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 (Solar Cells) http://www.qrg.northwestern.edu/projects/vss/docs/power/2-how-do-batteries-work.html Good description of batteries and link to how solar energy can recharge them

Photovoltaic Cells Sunlight strikes semi-conductor Electrons move Life is carbon-based for a reason Silicon atoms have the same capabilities When a sufficiently strong photon of sunlight hits the cell, it can knock an electron free. Since PV cells have electromagnetic fields, the electrons are propelled out of the cells, forming an electric current Read more: How Do Photovoltaic Panels Work? | eHow.com http://www.ehow.com/how-does_5221210_do-photovoltaic-panels-work_.html#ixzz1HEpoibmA http://www.youtube.com/watch?v=K76r41jaGJg Sunlight strikes semi-conductor Electrons move Energy can be stored in battery http://www.youtube.com/watch?v=K76r41jaGJg (1:07 mins)

Solar Cells ADVANTAGES DISADVANTAGES No pollutants Safe 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 Set-up demo before showing video, let run during video, then light on fire after video is complete http://www.teachersdomain.org/asset/eng06_vid_fuelcells/ (5:53 mins) Fuel Cell Flash Animation Bill Nye video http://www.pbs.org/wgbh/nova/sciencenow/3210/01.html (12:49 mins)

Hydrogen Fuel Cells ADVANTAGES DISADVANTAGES 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 Would do this as part of the review after all the presentations are completed

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 http://www.extremetech.com/article2/0,2845,1155270,00.asp

3 types of Heat Transfer

http://www.eere.energy.gov/solar/solar_heating.html 33

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 price No CO2 emissions Very low air and water pollution Need heat storage system Figure 16.11 Advantages and disadvantages of heating a house with passive or active solar energy (Concept 16-3). Question: Which single advantage and which single disadvantage do you think are the most important? Why? Very low land disturbance (built into roof or windows) High cost (active) Active system needs maintenance and repair Moderate cost (passive) Active collectors unattractive 34

What IS a Battery? Energy Storage System! As easy as a clock spring or a log Is that potential or kinetic? Have magnets for simple demo and discussion of negative and positive http://www.extremetech.com/article2/0,2845,1155268,00.asp Great history and construction of battery site; bottom pic is Duracell battery;

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.htm Battery 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

What’s the bridge to get there? Where are we now? Coal Gasification Where might we go? Hydrogen Fuel Cells What’s the bridge to get there? Photovoltaic Cells Do coal gasification demo and then jump into discussion of net energy – low due to the many steps