1. Renewable Resources
Unit 8

2. Energy usage at night in the United States
Energy usage at night worldwide
Where is the most consumption?

3. 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

5. 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

6. 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

7. Pros Cons 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*

9. 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

10. 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
Pros
No air or water pollution
No carbon emissions
Less expensive than coal produced electricity
New technology has made turbines more efficient

11. 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

12. 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?

14. Solar Energy The sun is the largest source of energy on the planet
Used 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

15. Cons Pros Initial cost is very high No pollution or carbon emissions
Can be affected by the weather
Need a backup generator or storage tank for night time
Pollution can inhibit photovoltaic cells
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

16. 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)

17. South facing windows allow for the most sun exposure
Roof overhangs allow shade to block some summer sun

18. 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

19. Solar thermal technology uses mirror lined panels that rotate with the sun to collect solar energy

20. 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

22. 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

23. Pros Cons 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

24. 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

25. Summarizing Questions
Why haven’t alternative energy sources replaced fossil fuels?
What is the major difference between a passive solar heating system and an active one?
Recall: Identify several types of biomass that could be used as energy.