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 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

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 2 nd 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.