Sustainable Energy Continued (Test 4)

Wind energy

The energy captured by transforming the motion of air into electrical energy using a turbine

Pros of wind energy

- no fuel costs or emissions

- generates income for farmers who rent land for turbines or sell electricity

- short planning and construction time

Cons of wind energy

- intermittent source,

- not enough wind everywhere,

- bird mortality

-power lines needed to transmit the electricity

Offshore wind

a breeze that blows from the land out over the water which would prove much better for wind turbines, but waters are too deep to put wind turbines in

Fuel cell

An electrical-chemical device that converts fuel, such as hydrogen, into an electrical current.

How does a fuel cell work?

1. Hydrogen fuel passed over the anode, oxygen passed over the cathode

2. An electron is removed from hydrogen creating a hydrogen ion

3. the electron passes through a circuit to create electricity and water is a by-product

Hindenburg Blimp

Filled with H gas and spark ignition. Reaction released water.

Reformer

device that extracts hydrogen from fuels (methane, ethanol, and ammonia~ when coupled to fuel cell, releases some pollutants (mostly CO2)

Biomass

wood, wood chips, bark, leaves, and starchy roots used to produce energy

True or False: Biomass is the dominant energy source in many developing countries such as Africa and Asia.

True.

- Charcoal production in Africa has increased according to the WHO

Charcoal production in Africa has resulted in

Deforestation and indoor air pollution

Because dung is being used for fuel:

NO nutrients are being returned to land as fertilizer

Biofuel

Created from crops with high oil content such as soybeans, sunflower, canola, and palm

Ethanol fuels are most popular in....

Brazil, where the fuel is sugar-cane derived AND the US where it's corn-derived

True or False: Ethanol contains 2/3 as much energy as gasoline

True

How is biofuel created ?

1. Grain is ground

2. Sugars are separated

3. Sugars are fermented to alcohol and distilled

Possible alternatives to corn as biofuel

Miscanthus x giganetus also called "elephant grass" can produce 5x as much biomass per acre of corn

Hydropower

Falling water through a penstock is used to turn a turbine

Hydroelectric dam

A device used to capture the energy of downward flowing water using a turbine

-requires large river and significant drop in elevation

How does a hydroelectric dam work?

Daytime: water flows through turbines, producing electricity

Nighttime: water pumped uphill to reservior for tomorrow's use

Advantages of hydropower

1. no fuel is required--> no pollution

2. relatively low operational costs

3. water in a reservior is renewed via rainfall

4. minimal waste- low disposal problems

Disadvantages of hydropower

- high investment costs

-precipitation dependent

- create river obstructions

The largest dam is the

Three Gorges Dam in China, being 1.4 miles long in the Yangzi River

The construction of the Three Gorges Dam in China caused...

- human displacement of 1.3 million people

- ecosystem deconstruction

- wildlife loss for dolphin and sturgeon population

- sedimentation

Geothermal energy

taps energy from hot springs, geysers, or volcanic activity

Most geothermal energy in the US lies in

California, Oregon, New Mexico, Utah, Nevada and Idaho

How does geothermal energy work?

1. Hot water pumped from deep underground

2. At the surface, pressure drops and water turns to steam. This generates electricity.

3. Cooled water pumped back into the Earth

Main disadvantage: geology dependent