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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 IS THE OCEAN (SEAWATER)

NO CURRENT TECHNOLOGY AVAILABLE TO TURN FUSION ENERGY INTO ELECTRICITY