SOLAR AND ALTERNATIVE ENERGY

1. SOLAR AND ALTERNATIVE ENERGY ENVIRONMENTAL SCIENCE CHAPTER 17

2. 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

3. 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

4. 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

5. 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

6. ACTIVE SOLAR SYSTEM SOLAR 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

7. 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

8. 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

9. 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

10. WIND ENERGY ADVANTAGES: • 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

11. 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

12. 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

13. 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