Environmental Education Environmental Education

Lecture Notes : 2.7

Energy Conservation

Content Content

• What is “energy”?

• Types of “energy resources”– Non-renewable – Renewable

• Energy conservation

What is “energy”?What is “energy”?

• “Energy is used for doing work”– e.g. provides warmth, ability to move and think

• Energy is everywhere

• Usable free energy is limited

– e.g. fossil fuels, nuclear power and hydropower • Need conservation of energy

– limited reserve

– overexploitation

Types of energy resources Types of energy resources

• Non-renewabe– Cannot be replenished or renewable

• Fossil fuels

• Nuclear energy

• Renewable

– Can be replenished or renewed • Geothermal

• Hydropower

• Ocean energy

• Solar energy

• Wind energy

• Biomass energy

Non-renewable: Fossil fuelsNon-renewable: Fossil fuels[1][1]

• Widely used

• Three kinds: – coals: hard, black and rock-like substance

– oil/petroleum: thick liquid layer

– natural gas: found near oil underground, mixture of flammable gases, main component is methane (CH4)

• Made up of decomposed plant and animal many millions years ago– decomposed and buried layer upon layer

– under high temperature and high pressure • If they are used up, they will be gone!!!

– Need to save

Non-renewable: fossils fuelsNon-renewable: fossils fuels[2][2]

• Grasshopper is used for extracting fossils fuels underground Sources: http://www.energy.ca.gov/education

Non-renewable: nuclear energyNon-renewable: nuclear energy[1][1]

• Energy is released when nuclear fission or nuclear fusion

• Nuclear fission:– use a neutron to bump a large nuclei

– the nuclei splits into several smaller fragments and releases energy

• Nuclear fusion:

– release of energy when small nuclei are fused together • Energy (from nuclear fission and fusion)

– boil water and turn generators for electricity

Non-renewable: nuclear energyNon-renewable: nuclear energy[2][2]

Nuclear fission:

A large nucleus splits into several small nuclei when bumped by a neutron and energy is released in this process.

Nuclear fission

Sources: http://www.atomicarchive.com/Fission/Fission1.shtml

Nuclear fusion:

Several small nuclei fuse together and release energy.

Nuclear fusion Sources:http://www.atomicarchive.com/Fusion/Fusion1.shtml

Renewable: solar energyRenewable: solar energy[1][1]

• Solar energy can be converted to electricity in 2 ways:– Solar thermal electricity – Solar cell (Photovoltaic energy)

• Solar thermal electricity – use heat energy from the sun to boil water– the stream formed then turn the turbine

• Solar cell (Photovoltaic energy)– convert radiation energy to electricity directly

Renewable: solar energyRenewable: solar energy[2][2]

The thermal energy of sun is converged by parabolic trough and used for boiling water. The steam is then used to push electricity generators.

Sources: http://www.energy.ca.gov/education

Parabolic trough (curve mirrors)

In solar cells, solar radiation energy is converted to electricity directly. Electrons are stroked out under sunlight and attracted to the other pole, so electricity occurs.

Sources: http://www.energy.ca.gov/education

Solar cell e-

Renewable: wind energyRenewable: wind energy[1][1]

• Used for grinding grains, pumping water, and generating electricity

pushed by wind

Produce electricity

• Wind push the blade

• Turn the turbine

• Electricity generated by generators

Sources:

http://www.energy.ca.gov/education

Renewable: wind energyRenewable: wind energy[2][2]

Group of wind turbine

• Increase electricity generation efficiency

Sources: http://www.energy.ca.gov/education

Renewable: hydropower Renewable: hydropower “Hydro” -- water; “hydropower” -- power of waterUsed for grinding flour or corn and generation of electricity

• dam is built to stop water flow of a river

• reservoir is formed behind dam

• the water is controlled to pass via turbine at the dam

• generators is then driven to produce electricity

Dam built for generating electricitySources: http://www.energy.ca.gov/education

damreservoir

Renewable: ocean energyRenewable: ocean energy

• Still in experimental stage, not common

• Three types:

– Waves energy

– Tidal energy

– Ocean thermal energy

Ocean energy: waves Ocean energy: waves

When the air flows, turbine is turned and it would drive the generator.Electricity is produced.

Sources: http://www.energy.ca.gov/education

Ocean energy: tidal and thermal Ocean energy: tidal and thermal

• Tidal energy– similar to hydropower plant

• dam traps the sea water when high tide• when tide drops, water flow turns the

turbine and drives the production of electricity of generator

• Ocean thermal energy – application of the temperature difference of

sea water

Renewable: Geothermal energyRenewable: Geothermal energy

“Geo” -- earth ; “thermal” -- heat

When the underground water is heated by magma, hot spring is formed.Sources: http://www.energy.ca.gov/education

Cool

Hot

Very hot

The steam can be used to turn generator for electricity.

Sources: http://www.energy.ca.gov/education

Hot spring

Renewable: biomass energyRenewable: biomass energy

• Biomass:– paper waste, trash, dead body, food waste, bark, sawdust and

housing rubber, etc

• Production of fuel during biological processes– e.g. fermentation

– targets products: e.g. hydrogen and ethanol

– they can be used for cars or generation of electricity

Energy conservationEnergy conservation[1][1]

• Most of the energy resources we use now is NON-RENEWABLE.

• If they are used up, they will be gone!!!

• We can:– Save energy

– Develop new energy resources

Energy conservationEnergy conservation[2][2]

• Recycle and reuse

• Save water

• Turning off electrical appliances when not use

• Suitable management and application of electrical appliances – e.g. lighting, water heater, washing machine and dry machine,

refrigerator and air conditioner

• Save energy in cooking

• Save energy in cars

Discussion Discussion

• Compare nuclear power and fossil fuel.• Discuss the relationship between living quality and

energy conservation. (Degradation of living quality?)• Are there any environmental destruction of using

renewable energy resources? (e.g.hydropower & geothermal)

• What kind of activities in our daily life are wasting energy resources?

• Does recycling really save energy?

Relevant WebsitesRelevant Websites 1. Guangzhou Institute of Energy Conversion, the Chinese Academy Of Scienceshttp://www.giec.ac.cn/

2. The Consumer Council—How to conserve energy?http://www.consumer.org.hk/pamphlet/chinese/energy.htm

3. Press release: Government and Hongkong Electric Sign Demand Side Management Agreementhttp://www.info.gov.hk/esb/refer/press/te971105.htm

4. Economic Services Bureau—Energy Supplieshttp://www.info.gov.hk/esb/chinese/respone/4.htm

5. Daily Information Bulletin -- Energy efficiency measures improve business competitiveness

http://www.info.gov.hk/gia/general/199810/29/1029106.htm

6. Daily Information Bulletin-- Energy Efficiency Labels for Electric Clothes Dryers

http://www.info.gov.hk/gia/general/199912/27/1224103.htm

7. Press release-- Energy Efficiency and Conservation Initiatives for 2000/01

http://www.info.gov.hk/efb/chinese/press/10022000.html

8. The Environmental Protection Department – Saving energy in your home

http://www.info.gov.hk/epd/chinese/pub/tips/saveng.htm