Renewable Resources
Unit 8
Electricity
The production of most electricity depends on a spinning turbine which is connected to a generator made up of copper and an electromagnet
When the electromagnet is rotated, a magnetic field is created which causes electrons to flow through the copper wire- electricity
Renewable Energy
Almost 40 years after the Arab Oil Embargo, over 60% of our oil is still imported
In 2004, 69% of electricity was produced by burning fossil fuels (mostly coal)
Renewable energy produced 10% Renewable resources can be replaced in an
ecological cycle Water, wind, geothermal, solar, biomass
Energy usage at night in the United States
Energy usage at night worldwide
Where is the most consumption?
Water
Hydroelectric power is produced when the energy of falling water spins a turbine
Dams create large bodies of water that can flow throw turbines connected to generators
Hydropower generates ~10% of electricity in the US Supplies 28million households and replaces 500
million barrels of oil each year Canada sells a lot of electricity to the Northern
states from their hydroelectric plants
Pros Hydropower is
cheaper than fossil fuels
No pollution Costs remain relatively
low and stable
Cons Dams have large
environmental impacts Almost all of the areas
in the US that can be developed for hydropower have been so we won’t see an increase
*The Hoover Dam produces 4 billion kilowatt hours of electricity each year which serves 1.3 million people*
Wind Wind is a source of clean, renewable
energy Windmills were used before power plants
provided electricity to rural areas The blades on a wind turbine spin to
power a generator
Pros No air or water
pollution No carbon emissions Less expensive than
coal produced electricity
New technology has made turbines more efficient
Cons There are few sites in
the US with reliable wind to generate power (mostly the Great Plains, CA and TX)
Change the appearance of the landscape
Create noise pollution The cost can fluctuate
depending on how far from the wind farms you are
Geothermal Energy The natural heat or hot water trapped below
the Earth’s surface can be used to heat homes, produce electricity and power industries
Nearly 2 dozen countries use geothermal energy
Hawaii and Iceland are the two biggest producers of
geothermal energy
Pros Create minor
environmental impacts Lower costs (coal
$3.85/KWh, geo $0.003/KWh)
No cost fluctuation because of constant temperature inside the earth
Can be easily installed for personal homes and business use
Cons Corrosive minerals in
steam can damage pipes Available for large scale
use in limited areas If water is used faster than
it is recharged, it can run out
Checkpoint: Why won’t geothermal energy become a major source of electricity for most states?
Solar Energy
The sun is the largest source of energy on the planetUsed to grow our food, powers the water
cycle and creates wind Solar energy can be used to heat buildings
and water and provide electricity Solar energy is harnessed using passive
or active solar heating systems
Pros No pollution or carbon
emissions Can create electricity
off the grid (good for remote areas)
Cost efficient- free electricity after cost of installation
Never running out
Cons Initial cost is very high Can be affected by the
weather Need a backup
generator or storage tank for night time
Pollution can inhibit photovoltaic cells
Passive Solar Heating
Occurs when light energy passes through glasses and is trapped (like a greenhouse)
Buildings use things like water, bricks, stone or concrete to absorb the heat in passive collectors
The air in the collector is heated and rises through a vent at the top of a collector and cool air enters at the bottom and is heated up (convection current)
South facing windows allow for the most sun exposure
Roof overhangs allow shade to block some summer sun
Active Solar Heating
Requires electricity for pumps or fans to distribute heat
Energy is collected in flat plate collectors Air or water flowing through the collector is
heated and pumped into a storage tank Photovoltaic cells convert sunlight directly
into electricity
Solar thermal technology uses mirror lined panels that rotate with the sun to collect solar energy
Solar City Rizhao, a coastal city in China is 99% solar
powered The achievement was the result of three factors:
Government policy that encouraged solar energy use and financially supports research and development,
local solar panel industries that seized the opportunity and improved their products,
The strong political will of the city's leadership to adopt it
New buildings must install solar panels Other cities are starting to follow
Biomass
Refers to any organic substances produced by living organisms and used as a source of energy
Worldwide, it is a very important use of energy (wood) In the US, the use of wood for heat in the homes have
increased Biodegradable waste is also used as biomass
Paper industry generates more the ½ its energy from its own waste products
Biomass ranks 2nd to hydropower in renewable energy production
Pros Can be made locally Liquid fuel can be
derived from biomass Gasohol (ethanol and
gasoline)
Cons Large areas of land
are needed for energy plants
The cost can change with the crops being produced
Some materials are not available all year
Economics of Alternative Energy
Most alternative energy sources are expensive to start
The long term savings and the independence of fossil fuels is where the true savings are
There are tax incentives for individuals to become more energy efficient and tax breaks for businesses
Summarizing Questions
1. Why haven’t alternative energy sources replaced fossil fuels?
2. What is the major difference between a passive solar heating system and an active one?
3. Recall: Identify several types of biomass that could be used as energy.