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SOLAR AND ALTERNATIVE ENERGYENVIRONMENTAL SCIENCECHAPTER 17

+SOLAR ENERGY Most of the Earth’s energy

comes from the sun Most living organisms get their

energy from the sun Fossil fuels are the remains of

long dead organisms that relied on the sun

The sun is vital to the water cycle – there is no “new sources” for fresh water

Hydroelectric power comes from flowing water

Uneven heating of the Earth by the sun creates wind

Wind can also generate electricity

+SUN AS FUEL Thermonuclear fusion creates the sun’s energy

TWO Hydrogen nuclei fuse together to create ONE larger nucleus.

Hydrogen has an atomic number of 1 the new larger nucleus has an atomic number of 2 so the element is now Helium

Some of the energy from the two hydrogen nuclei is released when they fuse

This energy is in the form of visible light and infrared

+SOLAR POWER

ADVANTAGES “FREE” ENERGY CLEAN – (no mining,

wastes)

NONPOLLUTING – (no CO2, toxic gases produced)

COST OF EQUIPMENT MAY BE RECOVERED OVER TIME

DISADVANTAGES SUNLIGHT IS NOT

CONSTANT – (no sun at night, cloudy, rainy days)

SOLAR EQUIPMENT IS EXPENSIVE

CURRENT TECHNOLOGY IS NOT EFFICIENT

+PASSIVE SOLAR HEATING Sunlight energy used to heat

building directly Can NOT be used to produce

electricity Buildings must be DESIGNED

for passive solar Building materials must be

light ABSORBENT (stone, brick, concrete)

Windows, skylights and glass enclosures should face SOUTH

Good INSULATION and dark materials inside to maximize sunlight energy

+ACTIVE SOLAR SYSTEMSOLAR COLLECTORS

Made of three parts: Large flat box with an insulated

black metal base Tubes filled with water are

located above the base Top layer is a thick piece of glass

Tubes collect the sun’s energy as heat and pumps move the hot water into the house. The hot water can be used as is or converted to steam to generate electricity

Uses energy from sunlight to produce heat and electricity

Needs fans, tubes, pumps, tanks to work

Solar collectors gather energy from the sunlight

Largest solar energy plant uses oil filled tubes heated by curved mirrors in the Mojave Dessert in California and Nevada

+PHOTOVOLTATIC CELLS PRODUCES ELECTRICITY

DIRECTLY FROM SOLAR ENERGY

TWO THIN WAFERS OF SILICON SEMICONDUCTORS

ENERGY FROM THE SUN HITS THE SILICON AND KNOCKS ELECTRONS FREE

THE ELECTRONS MOVE ALONG THE BOTTOM LAYER –PRODUCING ELECTRICAL CURRENT

EX: calculators, outdoor lights, watches, flashlights, cell phone and laptop chargers, cars

+HYDROELECTRIC ENERGY Flowing water contains

KINETIC energy (energy from movement)

Moving water generates electricity by turning turbines

Huge dams are built across waterways (rivers and streams)

Controls the movement of water ensures a constant flow to generate electricity

Creates lakes which can be used as recreation areas, control flooding downstream, water storage for irrigation and homes

ADVANTAGES Nonpolluting Available where ever there is

water Cheaper than fossil or nuclear

fuels

DISADVANTAGES Changes habitat, dries wetlands Can harm/kill native species Raises water temperature

downstream Changes soil causing erosion

and soil depletion

+TIDAL ENERGY OCEAN MOVEMENT CONTAINS

MASSIVE ENERGY TURBINES ROTATE FREELY (IN OR

OUT) WITH OCEAN TIDES USED IN CANADA AND IRELAND

ADVANTAGES: FREE ENERGY CONSTANT ENERGY

DISADVANTAGES:

VERY EXPENSIVE EQUIPMENT HAS TO BE LOCATED IN AN INLET

OR BAY LONG DISTANCE FOR

ELECTRICITY GENERATED TO TRAVEL

+WIND ENERGYADVANTAGES:

FREE, CLEAN, CHEAP

DISADVATAGES:

WIND ISN’T CONSTANT NEED LARGE SPACE FOR WIND

FARMS DISTANCE ELECTRICITY NEEDS

TO TRAVEL

Wind energy has been used since ancient times for pumping water, moving ships and grinding grain

Today we use aerogenerators or turbine generators

Traditional or horizontal have three blades and are on long poles

Vertical have two long blades that rotate like an upside down eggbeater

Wind speed must be 15 miles per hour or greater for traditional

Vertical can generate electricity at lower wind speeds

+GEOTHERMAL ENERGY Energy from naturally occurring

radioactive decay heats the Earth from inside

This heat melts rock - called magma (volcanoes)

Heated rocks warm ground water (hot springs) and turn ground water into steam (geysers like “Old Faithful”)

Geothermal energy can be used to heat hot water and buildings and generate steam to turn turbines to make electricity.

Since 1904, Laradello, Italy has used geothermal energy to produce electricity

+GEOTHERMAL ENERGY COUNTRIES THAT HAVE

VOLCANIC ACTIVITY – AND USE GEOTHERMAL ENERGY TO GENERATE ELECTRICITY:

ICELAND (80% of the country)

ITALY USA (in California and

Hawaii) NEW ZEALAND AUSTRAILIA CHINA INDIA

+NUCLEAR FUSION OCCURS WHEN TWO ATOMIC NUCLEI JOIN TOGETHER (FUSE) TO BECOME ONE LARGER NUCLEUS

NUCLEAR FUSION IS THE SOURCE OF THE SUN’S ENERGY (TWO HYDROGEN NUCLEI JOIN TOGETHER TO MAKE A HELIUM ATOM)

FUEL IS DEUTERIUM – A HYDROGEN ISOTOPE

THE BIGGEST SOURCE OF DEUTERIUM (2H) IS THE OCEAN (SEAWATER)

NO CURRENT TECHNOLOGY AVAILABLE TO TURN FUSION ENERGY INTO ELECTRICITY