Renewable Energy

Energy

• An essential part of modern society

• Need reliable supply

• The U.S. constitutes less than 5% of the world population, but uses 26% of the world’s energy.

Primary Sources of Electricity50%: Coal

40%:• Natural gas• Oil• Nuclear

9%: Hydroelectricity

1%: Solar, Wind, Geothermal, Other

Vocabulary

• Alternative: options besides fossil fuels.

• Renewable: energy source that is replaced or restored as it is used.

• Nonrenewable: once you burn them, they are used up.

Need for Alternative Energy

• Burning fossil fuels causes air pollution and is a big contributor to global warming.

• Oil spills, acid rain, and national security are other problems associated with fossil fuels.

• Fossil fuels will eventually run out.

Increase in Renewable Energy

• Government has began to recognize the need for renewable energy sources.

• Many states are now requiring that renewable energy sources make up a certain amount of its electricity supply.

Solar Energy

• Solar energy—power from the sun

• Advantages: clean, inexhaustible

• Disadvantages: Needs sun (generate electricity only on sunny days), not always reliable, needs huge amounts of land.

Nevada Solar One • Example of large solar power plant

• Boulder City, NV (40 miles from LV)

• 300 acres, the size of about 200 football fields

WIND ENERGY

WIND ENERGY

WIND ENERGYAdvantages:

• Fueled by the wind, so it's a clean fuel source

• No combustion of fossil fuels, no air pollution

• Wind supply is abundant and can’t be used up (renewable)

• Lower cost

WIND ENERGY

Disadvantages:• When the wind isn’t blowing, the windmills aren’t

turning and no power is being generated or sometimes the wind can be too strong.

• A single windmill will not produce a lot of electricity. Instead, hundreds or thousands are needed depending on the production goals.

• For some people, a lot of windmills can be an eyesore.

• Take a large amount of space• Noise produced by the rotor blades • Birds have been killed by flying into the rotors

Biomass

• Energy derived from burning organic material such as wood, alcohol, and garbage.

Pros and Cons of Biomass

• Advantages:

Cheap source of energy, reduces landfills.

• Disadvantages:Causes air pollution.

May use more energy than it creates.

Hydroelectric

• Energy produced by running water.

• A dam is built to hold back the water, forming a lake behind the dam.

• As water is released, its force turns turbines in the dam that generate electricity.

Hoover Dam near Las Vegas

Turbines inside Hoover Dam

AdvantagesClean energy

Low cost

DisadvantagesLake formed upstream fills with sediment.Downstream of dam, erosion increases.Land above the dam is flooded and wildlife habitats are destroyed.

Tidal Energy

Uses energy from the tides to create electricity.

Advantages: Reliable and predictable

Disadvantages: Expensive to build and limited availability of sites with enough tidal range.

GEOTHERMAL ENERGY

Geothermal energy is the use of Earth’s natural heat.

Geo means

Thermal means

Crust

Mantle

Outer core

Inner core

Geothermal Reservoir

When the hot water and steam accumulate in permeable and porous rock, a geothermal reservoir forms.

When the hot water and steam accumulate in permeable and porous rock, a geothermal reservoir forms.

Powerful Energy Source

Geothermal reservoirs can reach

temperatures of 700˚F/370˚C

(more than 3 times boiling).

Generation of Electricity

Production Well

Injection Well

Geothermal power plants have no smoky emissions.They emit water vapor.

Those white plumes you see at geothermal power plants are steam (water vapor). Geothermal plants do not burn fuel or produce smoke.

Those white plumes you see at geothermal power plants are steam (water vapor). Geothermal plants do not burn fuel or produce smoke.

Advantages of Geothermal Energy• Clean energy – no burning, little to no air pollution,

no fossil fuels

• No “smog” or acid rain emissions

• Uses little land, less than all other energy types

• Is renewable and sustainable

• Generates continuous, reliable power – 24 hrs/day

• Less expensive than other energy plants

Disadvantages of Geothermal

• Limited locations (no resources in Eastern USA)

• Risks of being near faults and volcanoes

• Steam and flash plants – release some gases from deep in Earth

• Steam from some plants may be unappealing (but still better than fossil fuel plants)

Geothermal Power Plants