Sources of Energy:Sources of Energy:Student Learning GoalStudent Learning Goal

The student will be able to describe a The student will be able to describe a variety of renewable and non-variety of renewable and non-renewable sources of energy and renewable sources of energy and identify the strengths and identify the strengths and weaknesses of each. (E3.5)weaknesses of each. (E3.5)

Sources of EnergySources of Energy

SPH4CSPH4C

Steam TurbinesSteam Turbines

Both coal and nuclear power plants Both coal and nuclear power plants use steam turbines to turn their use steam turbines to turn their generators.generators.

Steam TurbinesSteam Turbines

Burning coal is an Burning coal is an exothermicexothermic chemical reaction: it produces heat.chemical reaction: it produces heat.

Coal: advantageCoal: advantage

The main advantage of coal is that it is The main advantage of coal is that it is the cheapest way of producing the cheapest way of producing power.power.

(China in particular has vast reserves.)(China in particular has vast reserves.)

Coal: disadvantageCoal: disadvantage

The main disadvantage is that the The main disadvantage is that the burning releases pollutants: not only burning releases pollutants: not only greenhouse gases such as carbon greenhouse gases such as carbon dioxide but also toxins such as dioxide but also toxins such as mercury.mercury.

Coal: disadvantagesCoal: disadvantages

Producing coal is also environmentally Producing coal is also environmentally destructive.destructive.

If coal is less than 70 m underground, If coal is less than 70 m underground, it is removed by digging it is removed by digging open pitsopen pits::

Coal: disadvantagesCoal: disadvantages

Or by removing mountaintops:Or by removing mountaintops:

Coal: disadvantagesCoal: disadvantages

A lot of coal is deeper underground, A lot of coal is deeper underground, but mining it risks miners’ respiratory but mining it risks miners’ respiratory health and safety.health and safety.

The much-publicized rescue of the Chilean coal miners

Nuclear plantsNuclear plants

In nuclear plants, it is the radioactive In nuclear plants, it is the radioactive decay of uranium that produces the decay of uranium that produces the heat to boil the water.heat to boil the water.

The water that turns the steam turbine is in a separate loop.

Nuclear: advantageNuclear: advantage

The main advantage of nuclear power The main advantage of nuclear power is that it does not produce any is that it does not produce any pollutants.pollutants.

Nuclear: disadvantagesNuclear: disadvantages

However, disposing of the nuclear fuel However, disposing of the nuclear fuel after use can be a problem because after use can be a problem because it is still radioactive.it is still radioactive.

Nuclear: disadvantagesNuclear: disadvantages

And mining uranium produces toxic, And mining uranium produces toxic, radioactive radioactive tailingstailings (in Canada, half (in Canada, half a million tonnes each year).a million tonnes each year).

HydroHydro

““Hydro” is short for Hydro” is short for hydroelectric, power hydroelectric, power generated by water generated by water turbines that turn the turbines that turn the energy of the water energy of the water flow into the rotational flow into the rotational energy needed to energy needed to power a generator.power a generator.

HydroHydro

Across Canada, hydro is the #1 source Across Canada, hydro is the #1 source of energy (#2 in Ontario).of energy (#2 in Ontario).

Hydro: AdvantageHydro: Advantage

Hydro plants are clean in that they do Hydro plants are clean in that they do not emit pollutants, including not emit pollutants, including greenhouse gases.greenhouse gases.

The Sir Adam Beck generating complex.

Hydro: ExplainedHydro: Explained

Video by Ontario Power Generation:Video by Ontario Power Generation:http://www.youtube.com/watch?v=cEL7yc8R42k

Hydro: DisadvantageHydro: Disadvantage

But they still disrupt ecosystems But they still disrupt ecosystems because of the large because of the large damsdams required. required.

Satellite view of the Three Gorges Dam in China, capable of generating 18.2 GW.

DamsDams

The building of a dam results in The building of a dam results in flooding above the dam, displacing flooding above the dam, displacing populations.populations.

Three Gorges before

Three Gorges after

DamsDams

Dams also create barriers to fish Dams also create barriers to fish spawningspawning (reproduction) areas. (reproduction) areas.

Bonneville Dam (Oregon) spawning ladder for salmon

DamsDams

And the lakes formed above dams are And the lakes formed above dams are vulnerable to vulnerable to sedimentationsedimentation, when , when the silt that would flow downstream the silt that would flow downstream builds up in the lake.builds up in the lake.

Low-impact hydroLow-impact hydro

Low-impact hydro dams are smaller Low-impact hydro dams are smaller and carefully planned to minimize and carefully planned to minimize disruption.disruption.

6% of Ontario’s energy now comes 6% of Ontario’s energy now comes from these dams.from these dams.

Water as a resourceWater as a resource

The careful use of water as a power The careful use of water as a power source is particularly important source is particularly important because water is a resource itself.because water is a resource itself.

Water as a resourceWater as a resource

Farming accounts for 70% of the Farming accounts for 70% of the world’s water use.world’s water use.

Water as a resourceWater as a resource

And as the world’s population grows And as the world’s population grows and the demand for food grows, water and the demand for food grows, water use by farming will increase unless use by farming will increase unless we use more sustainable practices, we use more sustainable practices, e.g. e.g. drip irrigationdrip irrigation..

Solar EnergySolar Energy

SolarSolar energy energy is power is power generated generated by by harnessing harnessing the energy the energy of the Sun’s of the Sun’s rays.rays.

Active Solar TechnologyActive Solar Technology

Mirrors and metal plates can be used Mirrors and metal plates can be used to concentrate the sun’s rays to heat to concentrate the sun’s rays to heat air or water.air or water.

This is called This is called active solar active solar technologytechnology..

Solar OvensSolar Ovens

Concentrating the Sun’s rays can even Concentrating the Sun’s rays can even be used to cook food in be used to cook food in solar ovenssolar ovens..

Concentrating Solar Concentrating Solar TechonologyTechonology

Mirrors can even be used to Mirrors can even be used to concentrate the Sun’s rays to heat concentrate the Sun’s rays to heat water to drive generators.water to drive generators.

Solar Two, Mojave Desert, California

Solar panelsSolar panels

Solar panelsSolar panels are most effective when are most effective when they are angled toward the Sun (not they are angled toward the Sun (not necessarily straight up).necessarily straight up).

Solar panelsSolar panels

Solar panelsSolar panels are most effective when are most effective when they are angled toward the Sun (not they are angled toward the Sun (not necessarily straight up).necessarily straight up).

The most effective angle will be equal The most effective angle will be equal to the latitude of the panel.to the latitude of the panel.

Solar CellsSolar Cells

Solar panels contain Solar panels contain photovoltaic cellsphotovoltaic cells..

The cells are made of The cells are made of semi-conductorssemi-conductors such as silicon. such as silicon. When light strikes When light strikes the cell, an electric the cell, an electric current is produced.current is produced.

Solar = DCSolar = DC

This current is direct This current is direct current (DC).current (DC).

It can be stored in a It can be stored in a rechargeable battery rechargeable battery or be converted to AC or be converted to AC (by an (by an inverterinverter) to ) to be used by household be used by household appliances.appliances.

Solar = $Solar = $

Houses with solar panels can sell Houses with solar panels can sell energy back to the grid when they energy back to the grid when they are producing more than is needed.are producing more than is needed.

DisadvantagesDisadvantages

The disadvantages of solar energy are:The disadvantages of solar energy are:

• The expense needed to build the The expense needed to build the panelspanels

• It doesn’t produce energy at night (or It doesn’t produce energy at night (or as much when cloudy)as much when cloudy)