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’sPro’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.

Pros1.Renewable2.Abundant3.Sustainable4.Environmentally Friendly5.Good Availability6.Reduces Electricity Costs

7.Many Applications8.Shared Solar9.Silent10.Financial Support from Government/State11.Low Maintenance12.Technology is Improving

Cons1.Expensive2.Intermittent3.Energy Storage is Expensive4.Associated with Pollution5.Exotic Materials6.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’sPro’s- RenewableCon’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.