Renewable Energy

Solar Energy

Renewable energy: energy from sources that are constantly formed Can include: ▫Solar ▫Wind ▫Hydropower  moving water ▫Earth’s heat

Sun Basics Sun is a medium-sized star that radiates energy from nuclear fusion reaction in core Only a small amount of sun’s energy reaches Earth ▫Amount that reaches Earth is enough to power wind, plant growth, and water cycle Can use direct or indirect solar energy

Passive Solar Heating Passive solar heating: uses the sun’s energy to heat something directly In Northern Hemisphere  south facing windows receive most solar energy ▫Buildings have large windows that face south  allows more sunlight to enter

How it works: ▫During the day  sun enters through the windows and warms the house/building ▫At night  heat is released slowly to keep house/building warm Buildings and homes must be well insulated with thick walls and floors ▫Prevents heat loss

Buildings are oriented (positioned) according to yearly movement of sun ▫Summer  sun’s path is high in the sky  Overhang of roof shades the building and keeps it cool ▫Winter  sun’s path is lower in sky  Sunlight shines into home and warms it

Active Solar Heating Active solar heating: energy from the sun being gathered by collectors which is used to heat water or a buildings Solar collectors are mounted on a roof to capture Sun’s energy ▫Liquid is heated by the sun as it flows through solar collectors ▫Liquid then pumped through a heat exchanger which heats water for the building

Solar Cells Solar cells are also known as photovoltaic cells Convert the Sun’s energy into electricity ▫Energy is stored in batteries for electricity when sun is not shining Used to power calculators, space stations, sidewalk lights, cell phone chargers Not used for all of our energy needs  only produce a small amount of electricity ▫Also requires extended periods of sunshine

Energy production from solar cells has doubled every 4 years since 1985 Have become increasingly efficient and less expensive Great potential for use in developing countries ▫Energy consumption is minimal ▫Electricity distribution networks are limited

Biomass- Power from Living Things

Biomass fuel: plant material, manure (animal feces), and any other organic matter that is used as an energy source Wood and dung (poop) are major sources of energy in developing countries More than half of all wood cut in the world is used as fuel for heating and cooking ▫Releases harmful air pollution when burning wood ▫Can lead to habitat less, deforestation, less oxygen, and soil erosion

Methane Methane gas: by-product of when bacteria decompose organic wastes Gas can be burned to generate heat or electricity Given off by cow manure Some landfills generate electricity by using the methane from the decomposition of trash

Alcohol Ethanol: an alcohol made by fermenting fruit or agricultural waste ▫Fermentation: the chemical breakdown of a substance by bacteria and other microorganisms ▫Agricultural waste- sugar cane, corn, rice Corn is a major source in the United States Gasohol: a blend of gasoline and ethanol that cars and trucks can run on ▫Produces less air pollution than fossil fuels

Advantages No harmful emissions  no harmful carbon dioxide is given off Clean energy  while it gives off carbon dioxide, plants use it to make food Abundant and renewable  come from living sources and don’t run out unless overused

Advantages cont. Reduces dependency on fossil fuels Reduces landfills  waste that would be harmful to environment can be turned into something useful Can be used to create different products  different types of fuels

Disadvantages Expensive  costs a lot of money to care for live animals, costs money to harvest corn, rice, and sugar Inefficient  doesn’t produce as much energy as fossil fuels Can be harmful to environment Consume more fuel Require more land  need land to easily burn biomass

Wind Energy

Wind Power Wind: movement of air masses ▫Cold air sinks ▫When cold air sinks, warm air rushes in to fill its spot  get wind Wind power converts the movement of wind into electric energy ▫Wind turns blades around a motor which spins a turbine to generate electricity Fastest growing energy source in world

Wind Farms Wind farm: large layout of wind turbines Small wind farms with 20 or less turbines are common in windy, rural areas Turbines take up little space ▫Farmers add wind turbines to their land and then sell electricity locally

Parts of a Turbine Blades: lifts and rotates when wind is blown over them causing the rotor to spin ▫Can either have 2 or 3 blades Rotor: blades and hub together that spins Controller: starts up machine at wind speeds of about 8-16 mph and shuts off at winds about 55 mph Generator: produces electricity Tower: supports the structure of the turbine ▫Higher and taller towers capture more energy

Turbines- How They Work 1.Turbine mounted on a tower to capture the most energy 2.Wind blows and hits a two or three blade propeller which causes it to spin around a rotor 3.Rotor connected to a main shaft that spins a generator to create electricity Can either be produce electricity for a single building or connected to an electricity grid for widespread distribution

Benefits Clean fuel source  doesn’t cause air pollution, acid rain, or increase greenhouse gases Abundant supply Cost effective  one of lowest-priced energy sources Sustainable  constant supply Take up little space  can be built on existing farms

Disadvantages Requires an higher initial investment compared to fossil fuels Good wind sites are often in locations far away from cities that need the electricity May not be the most profitable  land may be more suitable for other purposes Not very visually appealing Can hurt local wildlife  birds can be killed flying into the rotors

Hydroelectricity- Power from Moving Water

What is it? “Hydro-” means water Hydroelectric energy: energy produced from moving water Renewable because you can’t stop all water from flowing One of the cleanest sources of energy ▫Why do you think this? Hoover dam in Nevada generates power for Nevada, Arizona, and California

Hoover Dam

How it Works 1.A hydroelectric dam is built across a flowing waterway 1.Dam built where there is a large drop in elevation  goes from high to low like a playground slide 2.As water is pulled downhill, it picks up speed 2.As water moves downhill inside the dam, it flows past a turbine 1.Flowing water past the turbine causes it to spin 2.Water isn’t changed as it passes through the turbine

3. Spinning turbine is connected to a generator ▫Spinning inside the generator creates electricity 4. Generator is connected to power lines that bring electricity to homes and buildings 5. Water flows back into the river on the other side of the dam Dams can pump water back up into it to create a backup source of power for when demands for electricity are high

Advantages Minimal pollution  nothing burned so no air pollution Inexpensive to operate and maintain Water that runs through the power plant is free by nature Dam holds water behind it  steady, constant flow of energy

Disadvantages Very expensive to build and require a large up-front investment Reservoir behind dam can dry up if not enough rain Dams can negatively affect ecosystems  loss of habitat, loss of populations Fish can be trapped Dam can burst Sediments build up behind the dam which causes the land below dam to not be as productive