Alternative Energy Sources Chapter 17

Hydroelectric Energy -Electricity that is produced from the energy of moving water. -Anything that has mass, and moves, has kinetic energy. -Harnessing moving water is a clean, readily available source of energy. -Has been around for centuries (water wheels) -Roughly 20% of the worlds electricity is generated by flowing water.

How it works: -water, behind the dam, is directed towards turbines. -Water pushes against the blades, causes it to spin “run” -This motion is transferred to coils of wires in generators -Coils spin through a magnetic field -Produces electricity

The pro’s and con’s of Dam’s Pro’s: -Renewable -Green -Reliable -Flexible -Safe -Flood control -Recreation

Cons: -Environmental consequence's -Fish migrations -Habitat destruction -Relocation (includes humans) -Drastic temperature changes -Expensive to build -Droughts

Other water sources: -Tides -Tidal surges are a great source of electricity (where available) -Pro’s: renewable, very clean, not typically disrupting normal flow (migrations), -Con’s: limited locations available, eye sore, affect benthic community. -Waves -Movement (up and down) waves create can be used to make electricity -Pro’s: renewable, clean, mostly anywhere -Con’s: expensive and difficult to harness, eye sore

Home work!! Read “The Ocean Resource” page 273 Answer questions 1 and 2 on page 273 In 2-3 sentences, explain whether or not this is a feasible solution to energy/water crisis found through out the world.

Solar Energy -Energy from the sun (which technically is the source for hydro and wind power as well) -Thermonuclear fusion (where the suns energy comes from) -High temps (on the sun) cause hydrogen nuclei to fuse creating helium nuclei -As helium forms, a loss of mass occurs, which is converted into heat and light energy. -We actually receive a miniscule amount of the energy that is created by the sun. -This energy can be harnessed and used to generate electricity.

Pros 1.Renewable 2.Abundant 3.Sustainable 4.Environmentally Friendly 5.Good Availability 6.Reduces Electricity Costs 7.Many Applications 8.Shared Solar 9.Silent 10.Financial Support from Government/State 11.Low Maintenance 12.Technology is Improving

Cons 1.Expensive 2.Intermittent 3.Energy Storage is Expensive 4.Associated with Pollution 5.Exotic Materials 6.Requires Space

Active and passive solar energy: devices are used to collect, store, and circulate heat produced from solar energy. -In active systems -Tubes, tanks, fluids, pumps, fans, and other stuff are used to collect and distribute -Can be used after the sun sets as well -Make use of collectors (ex. Solar panels) -In passive systems (collected, distributed, and stored naturally) -Relies more on the positioning of the house and windows -Oriented so open facing areas (windows) typical face south

Photovoltaic Cells: uses thin wafers of semiconductor material to produce electricity directly from the solar energy -Also called the solar cell -Produces electricity directly -Made of elements like silicon and/or selenium -Two layers, of the semiconductor, sun strikes it, causes electrons to move back and forth…viola electricity. -Very common today, signs, watches, etc…

Wind Power -Use of the wind to turn a source to generate electricity. Called aerogenerators. -Same basic pro’s and con’s of solar -Not as constant or steady though -and elaborate storage devices are typically required -Two basic types: -Horizontal axis (traditional) -Vertical axis (can be used in lower wind environments)

Geothermal -Heat energy generated within the earth. -Generated by the decay of radioactive elements -Hot enough to melt rock (magma) -Water trapped nears surface create steam (geysers) -Geo is used in areas where this source of heat is closer to the surface -Most of Iceland used geothermal to heat homes -Green houses take advantage of the heat to grow produce all year long -Several countries use it to produce electricity.

Pro’s and Con’s Pro’s -Renewable Con’s -Not available everywhere -Air is often polluted with toxic hydrogen sulfide in areas where is available -Mineral waste, salts, and toxic metals, tend to corrode pipes and boilers -Often a lack of water in these areas.

Nuclear Fusion -Occurs when two atomic nuclei fuse to become one larger nucleus. -Same process found on the sun -Scientist have not yet learned how to control and harness this energy. -Fuel for nuclear fusion is usually deuterium (a hydrogen isotope, readily found in the ocean) -Subjected to enormous pressure and temperature (magnetic field or a laser) Pro’s: less radio active waste, easier to obtain fuel. Con’s: technology not ready for it.