Energy Sources and Electricity

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1Summary 重點摘要

Hong Kong's electricity comes mainly from coal and natural gas. Fossil fuels cannot be replaced once used and burning them gives off carbon dioxide; solar and wind power are renewable, and saving electricity is something everyone can do.

2Vocabulary cards Vocabulary

3Step by step Steps

1. Step 1: Know the energy we use dailyOur daily life cannot go on without energy. Lights and air-conditioners run on electricity, cooking uses town gas or LPG, and cars run on petrol — each comes from a different energy source. Energy turns machines and moves vehicles; without it a city would grind to a halt. Knowing the energy around us is the first step to using it well. The kinds of energy also include wind, solar and geothermal power — more varied than we might imagine.
2. Step 2: Tell renewable from non-renewableEnergy falls into two groups by whether it can be replaced. Coal, oil and natural gas took millions of years to form and are gone once burned — non-renewable energy; the sun shines again tomorrow, the wind blows again and water keeps flowing — renewable energy. Using more renewable energy makes the Earth's resources last much longer. The Earth's fossil fuel reserves are limited; every bit burned is one bit less, so saving them cannot wait.
3. Step 3: Learn how Hong Kong makes electricityHong Kong's electricity comes mainly from power stations. The stations burn natural gas and coal to heat water into high-pressure steam; the steam spins turbines to generate electricity, and underground cables carry it to the sockets of every home. In recent years stations have used more natural gas instead of coal, and are developing wind and solar power to cut pollution. Two power companies supply the city; natural gas is now the main fuel, and the share of coal keeps falling.
4. Step 4: Understand why we save electricitySaving electricity is not only about saving money — it protects the environment too. Burning coal and natural gas for power gives off carbon dioxide, which gathers in the air and warms the Earth like a blanket; making electricity also uses up precious fuel. One hour less of air-conditioning means less emission, doing our bit to slow climate change. Global warming brings extreme weather and rising seas, and saving electricity is a real action to slow it down.
5. Step 5: Build power-saving habitsSaving power calls for daily habits. Switch off the lights whenever you leave a room; in summer set the air-conditioning at twenty-five to twenty-six degrees and let a fan move the air — cool yet economical; unplug the charger as soon as a phone or appliance is charged, so no power is wasted. Kept up every day, these small habits save a remarkable amount. Choose appliances with Grade 1 energy labels — they save power and money in the long run, and deserve first consideration when buying.
6. Step 6: Design a family energy planTurning saving into a family project works even better. Agree with your family on a before-we-leave checklist — lights off, cooling off, plugs out — and check each item before going out; compare the electricity bill together each month and see the reading fall as proof of your savings. With everyone taking part, the family saves money and grows a sense of green responsibility. Draw the savings as a chart on the fridge; when the whole family sees the progress, the motivation grows even stronger.

4Diagrams Diagrams

5Worked example Example

6Common mistakes Mistakes

7Quick check Quick check

8Recap Recap

• Energy divides into non-renewable and renewable.
• Hong Kong generates power mainly from natural gas and coal, sent to homes through the grid.
• Burning fossil fuels gives off carbon dioxide and causes global warming.
• Solar and wind power are the clean energy of the future.
• Lights off, cooling raised, plugs pulled — everyone can save electricity.