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.