Energy Sources and Power Generation
FoundationRenewables (solar, wind, hydro, biomass) replenish naturally; non-renewables (coal, oil, gas, nuclear) are finite. Fossil fuels give reliable power but emit CO₂; renewables are cleaner but weather-dependent.
- Renewable: solar, wind, hydro, biomass; Non-renewable: fossil + nuclear
- Fossil: reliable but CO₂-heavy; Renewables: clean but variable
- No perfect source — it's about the mix and lifecycle
§Text Passage
1Modern society cannot last a moment without electricity, and generating it needs energy sources. Sources fall into two families by whether they replenish naturally: solar, wind, hydro and biomass keep renewing themselves and are renewable; coal, oil, natural gas and the uranium used in nuclear power have finite reserves that shrink with every use, so they are non-renewable.
2Fossil fuels offer high energy density, reliable supply and low generation cost, and have dominated world electricity for over a century; but burning them emits carbon dioxide that drives global warming, plus air pollutants such as sulphur dioxide and suspended particulates, and their reserves will one day run out. Renewables run with near-zero carbon emissions and will never be used up, but depend on weather and location, so output is unsteady and needs battery storage and flexible grid management.
3Nuclear stations generate by nuclear fission, emitting no carbon dioxide and delivering large, steady output on a small land footprint; but uranium is a non-renewable resource, radioactive waste must be isolated safely for thousands of years, and past accidents have kept public wariness about nuclear safety high, so nuclear power remains hotly debated.
4In reality no energy source is perfect; every choice balances cost, supply reliability and environmental protection. Hong Kong has no large hydro resources or wind farms and imports nearly all its fuels; its generation mix centres on natural gas, coal and nuclear electricity, with the shares of natural gas and renewables gradually rising. Fossil-fuel and nuclear stations both produce heat that boils water into high-pressure steam, and the steam spins a turbine driving a generator; wind turbines and solar panels convert the wind's kinetic energy and light directly into electricity.
1Summary 重點摘要
Renewables (solar, wind, hydro, biomass) replenish naturally; non-renewables (coal, oil, gas, nuclear) are finite. Fossil fuels give reliable power but emit CO₂; renewables are cleaner but weather-dependent.
2Vocabulary cards Vocabulary
Energy that naturally replenishes — solar, wind, hydro.
Fuels from ancient remains: coal, oil, natural gas.
Energy from splitting uranium atoms; low CO₂ but radioactive waste needs careful handling.
CO₂ released by burning fuels — the main driver of global warming.
Energy with finite reserves that runs out — coal, oil, gas and nuclear.
Turning sunlight into electricity with panels — zero emissions in use, but weather-dependent.
Turbines turned by wind generate power; output varies with wind speed.
Dammed water falling from a height spins turbines to generate electricity.
Energy from biological material such as wood and waste — renewable.
3Step by step Steps
- Two categoriesThe test for classifying energy sources is whether they replenish naturally: solar, wind, hydro and biomass keep renewing themselves and are renewable; coal, oil, natural gas and the uranium used in nuclear power have finite reserves that shrink with every use, so they are non-renewable. This classification is the starting point of any discussion about energy choices and sustainable development — sort the categories first, and the comparison of pros and cons that follows has a firm footing.
- Renewables pros/consRenewables run with near-zero carbon emissions and will never run out; their weakness is dependence on weather and location: no solar power at night or under overcast skies, and wind turbines sit idle when the wind drops, so output is not steady. Adopting renewables on a large scale therefore requires battery storage and flexible grid management to keep the electricity supply stable and reliable.
- Fossil fuels pros/consFossil fuels offer high energy density, reliable supply and low generation cost, which is why they have dominated electricity generation worldwide for over a century; on the debit side, burning them emits carbon dioxide that drives global warming, plus air pollutants such as sulphur dioxide and suspended particulates that harm health, and coal and oil reserves are finite — one day they will run out, so alternatives must be planned early.
- NuclearNuclear stations generate by nuclear fission, emitting no carbon dioxide and delivering large, steady output on a small land footprint; but uranium ore is non-renewable, and radioactive waste must be isolated safely for thousands of years, which is extremely difficult to manage. Historical accidents, such as Chernobyl in 1986, also keep public wariness about nuclear safety high, so nuclear power remains a permanently contested option.
- Hong Kong's mixHong Kong has no large hydro resources or wind farms and limited land, so it imports nearly all its fuels; its generation mix centres on natural gas, coal and nuclear electricity, with the shares of natural gas and renewables gradually rising. The mix reflects a real-world trade-off — balancing cost, supply reliability and environmental protection — with no single perfect option, only adjustments based on practical conditions.
- How generation converts energyFossil-fuel and nuclear stations work the same way: burning or fission first produces heat, boiling water into high-pressure steam; the steam spins a turbine, which drives a generator to produce electricity — the energy passing in order from chemical or nuclear form to heat, then kinetic, and finally electrical. Wind turbines convert the wind's kinetic energy directly into electricity, and solar panels turn light straight into electricity, with no burning step at all.
4Diagrams Diagrams
5Worked example Example
Why is solar called 'clean' yet still has environmental considerations?
- No fuel is burned in operation → zero emissions while running
- But manufacturing panels takes energy and materials
- Battery storage and recycling add issues
- 'Clean' is relative — look at the whole lifecycle
- Answer: Solar panels burn no fuel while generating, so the operational stage is near zero-carbon — hence 'clean'. But manufacturing the panels consumes energy and materials, and batteries raise storage and recycling issues, so 'clean' is relative and must be judged over the whole lifecycle. Overall solar is still far cleaner than fossil fuels; in your answer, give both 'zero emissions in operation' and 'costs in production and recycling'.
6Common mistakes Mistakes
7Quick check Quick check
Q1Which of these are renewable: solar, coal, wind, natural gas, hydro?
Q2What is the biggest environmental problem of fossil fuels?
Q3What is the main risk of nuclear power?
Q4What is the energy conversion chain in a natural gas power station?
Q5Why is solar power described as 'unstable'?
8Recap Recap
- Renewable: solar, wind, hydro, biomass; Non-renewable: fossil + nuclear
- Fossil: reliable but CO₂-heavy; Renewables: clean but variable
- No perfect source — it's about the mix and lifecycle
- The test: does it replenish naturally (renewable vs non-renewable)?
- Nuclear is low-carbon but non-renewable, and its waste needs long-term isolation