Ch 181 Renewable Energy Today What is renewable energy Energy from sources that are constantly being formed 5 forms of Renewable Energy Solar energy Wind energy Hydroelectricity Biomass Geothermal energy ID: 515473
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Ch. 18: Renewable Energy
Ch. 18.1 Renewable Energy TodaySlide2
What is renewable energy?
Energy from sources that are constantly being formed
5 forms of Renewable Energy:
Solar energy
Wind energy
Hydroelectricity
Biomass
Geothermal energy Slide3
Misconception:
Many believe that using renewable energy is better for the environment than nonrenewable energy.
However, ALL SOURCES OF ENERGY affect the environmentSlide4
Solar Energy
Power from the sun
Sun radiates energy (fusion)
Only a small fraction reaches Earth
Used Directly & indirectly Slide5
Direct & Indirect Use of Solar Energy
Direct:
sun shines in a window and heats a room- the room is being heated by solar power
Indirect:
solar energy generating electricity in solar cells Slide6
Passive Solar Heating
Uses the sun’s energy to heat something directly
Simplest form of solar energy
Buildings must be oriented according to yearly movement of sun & must be well insulated
Ex: Cliff dwellingsSlide7
Active Solar Heating
Energy from the sun gathered by collectors and used to heat water or a building Slide8
Photovoltaic Cells
AKA: Solar cells
Convert the sun’s energy into electricity
Solar cells have no moving parts and they run on nonpolluting power. Slide9
So…why don’t solar cells meet our energy needs?
Produces a very small electrical current; therefore, would need hundreds of acres of solar panels just to meet needs of a small city
Require extended period of sunshine to produce electricity
Energy stored in batteries and supply electricity when the sun is not shining Slide10
Solar Cells Today
Despite limitations:
Solar cells have become
increasingly efficient
and less expensive
Potential for developing countries
Currently: provide energy for more than 1 million households in the developing world Slide11
Wind Power
coverts the movement of wind into electric energy
Fastest growing energy source in the world
Turbines-cost effective and can be quickly builtSlide12
Wind Farms
Large arrays of wind turbines
Don
’
t take up a lot of room
Farmers can add them to their land and still use the land for
other purposes
Allows them to
sell their electricityto local utility co. Slide13
An Underdeveloped Resource
Scientists estimate that the windiest spots on Earth could generate more than 10x the energy used worldwide
Problem?
Transporting electricity from rural areas where it is generated to urban centers where it is needed Slide14
Biomass
Power from living things
Plant material, manure, and any other organic matter that is used as an energy sources is called
biomass fuel
Fossil Fuels are organic-are they a biomass energy source?
Yes-but they are nonrenewable Slide15
Examples
Wood
Dung Slide16
Methane
Bacteria decompose organic wastes and one of the byproducts is
methane gas
.
Can be burned to generate heat and electricity
Cow manure power plant in Britain
Some US landfills generate electricity from decomposing trash Slide17
Alcohol
Liquid fuels can be derived from biomass
Ethanol can be made by fermenting fruit or agricultural waste
US=corn is major source of ethanol
Cars and trucks can run on
gasohol
=ethanol + gasoline Slide18
Gasohol
Produces less air pollution than fossil fuels
Some US states require the use of gasohol in vehiclesSlide19
Geothermal Energy
Power from the earth
Energy form heat in the Earth’s crust
In some areas, deposits of water in the crust are heated by energy within the EarthSlide20
Geothermal power plants
How does it work?
1. steam rises through a well
2. Steam drives turbines-generates electricity
3. Leftover liquid water is pumped back into the hot rock Slide21
Geothermal Energy
United States
Largest producer of geothermal energy
Largest in world: The Geysers in California- produces electricity for about 1.7 million households
Although geothermal energy is considered a renewable resource, the water in the rock formations must be managed carefully so that it is not depleted. Slide22
Hydroelectricity
Power from Moving Water
As rainwater flows across the land, the energy in its movement can be used to generate electricity-
hydroelectric energy
20% of the world’s electricity Slide23
Benefits of Hydroelectric Energy
Hydroelectric dams
Do not release air pollutants
Last longer than fossil fuel-powered plants
Provide flood control
Provide water for drinking, agriculture, industry, and recreationSlide24
Disadvantages
Dams change the flow of rivers
Disrupts ecosystems downstream
Salmon have been prevented from swimming upstream to spawn
Land behind dam is flooded-people are displaced
Dam Failure-if it bursts, people can be killed
Farmland below dam can become less productive
Decay of plant matter trapped in reservoirs can release large amounts of greenhouse gases Slide25
Micro-hydropower
Electricity produced in a small stream without having to build a big dam
Cheaper than large
dam projects
Permits energy to be generated from small streams in remote areas