📚 Energy Resources and Electricity Generation | 能源资源与发电原理
Energy resources are the foundation of modern civilisation. Every time you switch on a light, charge a phone, or ride a train, you are using energy that has been converted from a primary source into electrical power. Understanding the different types of energy resources and how electricity is generated is a core part of the Edexcel IGCSE Physics syllabus, and it is also essential knowledge for making informed decisions about our planet's future.
能源资源是现代文明的基础。每当你打开一盏灯、给手机充电或乘坐火车时，你都在使用从一次能源转换而来的电能。了解不同类型的能源资源以及发电原理是 Edexcel IGCSE 物理课程的核心内容，同时也是我们为地球未来做出明智决策所必需的知识。
1. What Are Energy Resources? | 什么是能源资源？
An energy resource is any material or natural phenomenon that can be harnessed to provide useful energy. In IGCSE Physics, we classify energy resources into two broad categories: renewable and non-renewable. A non-renewable resource is one that will eventually run out, such as coal, oil, natural gas, and nuclear fuels. A renewable resource is one that is continuously replenished by natural processes, such as sunlight, wind, water flow, tides, waves, and geothermal heat.
能源资源是可以被利用来提供有用能量的任何物质或自然现象。在 IGCSE 物理中，我们将能源资源分为两大类：可再生能源和不可再生能源。不可再生资源是终将耗尽的资源，例如煤、石油、天然气和核燃料。可再生能源是由自然过程持续补充的资源，例如阳光、风、水流、潮汐、波浪和地热。
The key principle in electricity generation is energy transfer: we convert one form of energy (such as chemical, kinetic, gravitational potential, or nuclear) into electrical energy. According to the law of conservation of energy, energy cannot be created or destroyed, only transferred from one form to another. This means that no generator can create energy out of nothing; it simply transforms it.
发电的关键原理是能量转移：我们将一种形式的能量（如化学能、动能、重力势能或核能）转换为电能。根据能量守恒定律，能量不能被创造或消灭，只能从一种形式转换为另一种形式。这意味着没有发电机能够凭空创造能量；它只是将能量转换形式而已。
2. Renewable and Non-renewable Resources | 可再生与不可再生能源
The table below summarises the main differences between renewable and non-renewable energy resources, which you should be able to recall and compare in your exam.
下表总结了可再生能源与不可再生能源的主要区别，你需要在考试中能够回忆并比较这些内容。
| Feature | 特征 | Renewable | 可再生 | Non-renewable | 不可再生 |
| Availability | 可用性 | Continuous, will not run out | 持续不断，不会耗尽 | Finite, will eventually run out | 有限，终将耗尽 |
| Examples | 例子 | Solar, wind, hydro, tidal, wave, geothermal, biomass | 太阳能、风能、水力、潮汐、波浪、地热、生物质能 | Coal, oil, natural gas, nuclear fuels | 煤、石油、天然气、核燃料 |
| Environmental impact | 环境影响 | Generally lower; some visual/noise pollution | 通常较低；有一些视觉/噪音污染 | Produces CO₂, SO₂ and other pollutants; radioactive waste | 产生二氧化碳、二氧化硫等污染物；放射性废料 |
| Reliability | 可靠性 | Dependent on weather/conditions; can be intermittent | 依赖天气/条件；可能间歇性 | Very reliable, available on demand | 非常可靠，按需供能 |
In an exam, you may be asked to state whether a particular resource is renewable or non-renewable, and to justify your answer by referring to how it is replenished. Always remember: the term "renewable" refers to the rate of natural replenishment, not the amount of energy stored.
在考试中，你可能会被要求指出某种资源是可再生还是不可再生的，并通过说明其补充方式来证明你的答案。始终记住："可再生"一词指的是自然补充的速率，而不是储存能量的多少。
3. Fossil Fuels and Nuclear Power | 化石燃料与核能
Fossil fuels — coal, oil and natural gas — tor to produce electricity. This is a chain of energy transfers: chemical → thermal → kinetic → electrical.
化石燃料——煤、石油和天然气——是由古代动植物残骸经过数百万年形成的。它们储存化学能，在燃料燃烧时释放。在化石燃料发电站中，燃料燃烧加热水产生高压蒸汽。蒸汽驱动涡轮机，涡轮机带动发电机旋转产生电能。这是一系列能量转换：化学能 → 热能 → 动能 → 电能。
Nuclear power stations work on a similar principle, but instead of burning fuel, they use nuclear fission. A uranium-235 or plutonium nucleus absorbs a neutron and splits into two smaller nuclei, releasing a huge amount of energy as heat. This heat is used to produce steam that drives a turbine. The energy released per kilogram of nuclear fuel is vastly greater than that from fossil fuels, which is why a small amount of fuel can generate enormous amounts of electricity.
核电站的工作原理类似，但不是燃烧燃料，而是利用核裂变。铀-235 或钚核吸收一个中子后分裂成两个较小的原子核，释放出巨大的热能。这些热量用于产生驱动涡轮机的蒸汽。每公斤核燃料释放的能量远远大于化石燃料，这就是为什么少量燃料就能产生大量电能的原因。
One of the major problems with both fossil fuels and nuclear power is waste. Fossil fuels release carbon dioxide (CO₂), a greenhouse gas that contributes to global warming, as well as sulphur dioxide (SO₂), which causes acid rain. Nuclear power produces radioactive waste that remains hazardous for thousands of years and must be stored securely. These environmental concerns are a major reason why renewable energy sources are being developed worldwide.
化石燃料和核能的主要问题之一是废料。化石燃料释放二氧化碳（CO₂）——一种导致全球变暖的温室气体，同时还释放二氧化硫（SO₂）——造成酸雨。核电产生的放射性废料在数千年内仍然具有危险性，必须安全储存。这些环境问题正是全球大力发展可再生能源的主要原因。
4. Solar and Wind Energy | 太阳能与风能
Solar energy can be harnessed in two main ways. Photovoltaic (PV) cells convert light energy directly into electrical energy; they have no moving parts, which makes them very reliable and low-maintenance. Solar panels (thermal collectors) absorb sunlight to heat water directly for domestic use, saving energy that would otherwise be used to heat water electrically. Solar energy is truly renewable and produces no pollution, but the amount of power obtained depends on the time of day, the season, the weather, and the latitude of the location. In the UK, solar power output is highly variable, so solar cells are best used in combination with other sources or with battery storage.
太阳能可以通过两种主要方式利用。光伏（PV）电池将光能直接转换为电能；它们没有运动部件，因此非常可靠且维护成本低。太阳能集热板（热收集器）直接吸收阳光加热生活用水，从而节省了原本用电加热水所需的能源。太阳能是真正的可再生能源，不产生污染，但获得的功率取决于一天中的时间、季节、天气以及所在地的纬度。在英国，太阳能输出非常不稳定，因此太阳能电池最好与其他能源或电池储能结合使用。
Wind energy uses the kinetic energy of moving air. Large wind turbines have blades that rotate when wind blows over them; this rotation drives a generator inside the turbine housing. Modern offshore wind farms, located in the sea where winds are stronger and steadier, can produce very large amounts of electricity. The main disadvantages of wind power are its intermittency — electricity is only produced when the wind blows — and the visual/noise impact on the local environment. Additionally, the efficiency of a single turbine is limited: no wind turbine can extract more than about 59% of the kinetic energy in the wind due to Betz's law.
风能利用运动空气的动能。大型风力涡轮机的叶片在风吹过时旋转；这种旋转驱动涡轮机舱内的发电机。现代海上风电场位于海上，风力更强更稳定，能够产生非常大量的电能。风力发电的主要缺点是间歇性——只有风吹时才能发电——以及对当地环境造成的视觉/噪音影响。此外，单个涡轮机的效率是有限的：根据贝兹定律，任何风力涡轮机最多只能提取风中约 59% 的动能。
5. Hydroelectric and Tidal Energy | 水力与潮汐能
e because the water supply can be controlled by opening and closing valves. It can also respond very quickly to changes in electricity demand, making it excellent for meeting peak loads. The main drawbacks are the high initial construction cost of dams and the flooding of large areas of land, which can destroy habitats and displace communities.
水力发电（HEP）利用水库中高处储存水的重力势能。当水被释放时，它流下并带动涡轮机旋转，涡轮机驱动发电机。能量转换链是：重力势能 → 动能 → 电能。水电非常可靠，因为可以通过打开和关闭阀门来控制水流量。它还可以非常快速地响应电力需求的变化，非常适合满足高峰负荷。主要缺点是水坝的初始建设成本高，以及淹没大面积土地，这可能破坏栖息地并迫使社区迁移。
Tidal energy harnesses the kinetic and gravitational potential energy of tidal water. A tidal barrage is a barrier built across a river estuary; as the tide rises, water flows through turbines to generate electricity, and as the tide falls, water flows back out, again turning the turbines. Tides are predictable because they are caused by the gravitational pull of the Moon and Sun, so tidal power is more reliable than wind or solar. However, tidal barrages are very expensive to build and can disrupt marine ecosystems and shipping routes.
潮汐能利用潮水的动能和重力势能。潮汐坝是建在河口上的屏障；当潮水上涨时，水通过涡轮机发电，当潮水退去时，水又流回，再次驱动涡轮机。潮汐是可预测的，因为它们是由月球和太阳的引力引起的，因此潮汐能比风能或太阳能更可靠。然而，潮汐坝造价非常昂贵，并且可能干扰海洋生态系统和航运路线。
6. Wave and Geothermal Energy | 波浪能与地热能
Wave energy is a form of renewable energy that captures the kinetic energy of ocean surface waves. Wave-powered devices come in many designs, but most work by using the up-and-down motion of waves to drive a generator. In one common design, the waves move a floating device up and down, and this motion drives a hydraulic pump or a linear generator. Wave energy has the advantage of being very predictable in certain coastal locations, but the equipment must survive harsh marine conditions, which can lead to high maintenance costs. The power generated is also variable because the height and frequency of waves change with weather conditions.
波浪能是一种捕获海洋表面波动能的可再生能源。波浪发电装置有多种设计，但大多数利用波浪的上下运动来驱动发电机。一种常见设计是波浪使浮动装置上下运动，这种运动驱动液压泵或线性发电机。波浪能的好处是在某些沿海地区非常可预测，但设备必须承受恶劣的海洋环境，这可能导致高昂的维护成本。由于波浪的高度和频率随天气条件变化，产生的功率也是可变的。
Geothermal energy comes from the heat stored inside the Earth. This heat originates from the slow radioactive decay of minerals deep within the Earth's core and from residual heat from the planet's formation. In volcanic regions — such as Iceland — hot rocks are close to the surface, so cold water can be pumped down and returns as steam, which is used to drive turbines. In non-volcanic regions, geothermal heat pumps can still provide space heating by extracting heat from the shallow ground. Geothermal energy is very reliable, produces constant baseload power, and has a small land footprint, but it is limited to areas with suitable geology and can release small amounts of harmful gases from underground.
地热能来自地球内部储存的热量。这些热量来源于地球核心深处矿物的缓慢放射性衰变以及地球形成过程中留下的残余热量。在火山地区——例如冰岛——热岩靠近地表，因此可以将冷水泵入地下，返回的蒸汽用于驱动涡轮机。在非火山地区，地源热泵仍然可以通过提取浅层地下的热量来提供空间供暖。地热能非常可靠，能够提供稳定的基荷电力，且占地面积小，但仅适用于地质条件合适的地区，并可能释放少量有害的地下气体。
7. Biomass Energy | 生物质能
Biomass is any organic material derived from plants or animals. Wood chips, agricultural crop residues, animal manure, and even food waste can all be used as biomass fuels. When biomass is burned, its stored chemical energy is released as heat, which can be used directly for cooking and heating, or to generate electricity in a power station. Alternatively, biomass can be processed to produce biofuels such as bioethanol and biodiesel, which can be used in vehicles.
生物质能是任何来源于植物或动物的有机材料。木屑、农作物残留物、动物粪便甚至食物垃圾都可以用作生物质燃料。当生物质燃烧时，其储存的化学能以热量形式释放，可以直接用于烹饪和供暖，或在发电站中用于发电。此外，生物质还可以加工成生物乙醇和生物柴油等生物燃料，用于车辆。
The main advantage of biomass over other renewables is that it provides dispatchable power — meaning it can be burned whenever electricity is needed, making it reliable. It is also considered carbon-neutral in a simplified sense, because the CO₂ released when biomass burns is balanced by the CO₂ absorbed by plants during their growth. However, this carbon neutrality can be debated when transport, processing, and land-use change are considered. Furthermore, large-scale biomass farming competes with food production for land, which raises ethical concerns.
生物质能相对于其他可再生能源的主要优势在于它提供可调度的电力——这意味着它可以在需要时随时燃烧发电，非常可靠。在简化意义上，它也被认为是碳中和的，因为生物质燃烧释放的 CO₂ 与植物生长过程中吸收的 CO₂ 相平衡。然而，如果考虑到运输、加工和土地利用变化，这种碳中和性仍有争议。此外，大规模生物质种植与粮食生产争夺土地，引发伦理问题。
8. How a Power Station Works | 发电站的工作原理
Almost all large-scale electricity generation — whether from coal, gas, nuclear fuel, or biomass — follows the same basic structure. The fuel (or nuclear reaction) produces heat, which boils water to create steam. The steam is pressurised and directed onto the blades of a turbine, causing it to spin at high speed. The turbine is connected to a generator, which consists of a rotating coil of wire inside a magnetic field. According to Faraday's law of electromagnetic induction, rotating the coil in the magnetic field induces an electromotive force (e.m.f.) across the ends of the coil, which drives a current in the external circuit.
几乎所有大规模发电——无论是燃煤、燃气、核燃料还是生物质——都遵循相同的基本结构。燃料（或核反应）产生热量，热量将水煮沸产生蒸汽。蒸汽被加压并喷射到涡轮机叶片上，使其高速旋转。涡轮机连接发电机，发电机由磁场中旋转的线圈组成。根据法拉第电磁感应定律，在磁场中旋转线圈会在线圈两端感应出电动势（e.m.f.），从而在外部电路中驱动电流。
The energy transfer chain for a thermal power station can be written as:
emical (or nuclear) energy → Thermal energy → Kinetic energy (turbine) → Electrical energy
Each step in this chain involves some energy loss, mainly as heat to the surroundings and as sound. The overall efficiency of a typical fossil-fuel power station is only about 30–40%. This means that for every 100 J of chemical energy in the fuel, only 30–40 J is converted into useful electrical energy; the rest is wasted. This is a key point for exam questions: you should be able to calculate efficiency using the formula:
这条链中的每一步都会产生能量损失，主要是以热和声音的形式散失到周围环境中。典型化石燃料发电站的整体效率仅为 30–40%。这意味着燃料中的每 100 J 化学能，只有 30–40 J 被转换为有用的电能；其余部分被浪费。这是考试题的关键点：你应该能够使用以下公式计算效率：
Efficiency = (Useful output energy ÷ Total input energy) × 100%
fuel and produces 175 MJ of useful electrical energy, its efficiency is (175 ÷ 500) × 100% = 35%.
例如，如果一个发电站从燃料中获得 500 MJ 能量并产生 175 MJ 的有用电能，其效率为 (175 ÷ 500) × 100% = 35%。
9. The National Grid | 国家电网
The National Grid is the network of cables and transformers that distributes electricity from power stations to homes, factories, schools, and offices across a country. At the power station, a step-up transformer increases the voltage of the generated electricity — for example, from 25 kV to 400 kV in the UK — before it is transmitted over long distances. At the consumer end, step-down transformers reduce the voltage to safer levels: 230 V for domestic use in the UK.
国家电网是将电力从发电站输送到全国各地的家庭、工厂、学校和办公室的电缆和变压器网络。在发电站，升压变压器将发电电压升高——例如在英国从 25 kV 升至 400 kV——然后再长距离传输。在用户端，降压变压器将电压降低到更安全的水平：英国居民用电为 230 V。
Why is it so important to transmit electricity at a very high voltage? The key reason is to reduce energy loss in the cables. When current flows through a transmission cable, energy is dissipated as heat according to the equation:
为什么以非常高的电压输电如此重要？关键原因是为了减少电缆中的能量损耗。当电流流过传输电缆时，能量会以热量形式耗散，根据方程：
Power loss = I²R
e by a factor of 10, the current needed to transmit the same power drops by a factor of 10, and the power loss drops by a factor of 100 (because I is squared). This is why high-voltage transmission is essential for efficient long-distance electricity distribution.
其中 I 是电流，R 是电缆的电阻。传输的功率为 P = V × I。如果我们将电压提高 10 倍，传输相同功率所需的电流将减少 10 倍，而功率损耗将减少 100 倍（因为 I 是平方关系）。这就是为什么高压输电对于高效的长距离电力分配至关重要。
, the current would be 1000 A and the power loss would be (1000)² × 2 = 2,000,000 W = 2 MW — 100 times greater!
例如，假设一根电阻为 2 Ω 的电缆传输 10 MW 的功率。如果输电电压为 100 kV，则电流为 (10 × 10⁶) ÷ (100 × 10³) = 100 A，功率损耗为 I²R = (100)² × 2 = 20,000 W = 20 kW。如果电压改为 10 kV，电流将为 1000 A，功率损耗为 (1000)² × 2 = 2,000,000 W = 2 MW——足足大了 100 倍！
10. Comparing Energy Resources | 比较能源资源
When comparing energy resources, examiners want you to weigh up their advantages and disadvantages. Below is a summary comparison of the main renewable resources you need to know for Edexcel IGCSE.
在比较能源资源时，考官希望你权衡它们的优缺点。以下是你在 Edexcel IGCSE 中需要掌握的主要可再生能源资源的比较总结。
| Resource | 资源 | Reliability | 可靠性 | Cost | 成本 | Main Disadvantage | 主要缺点 |
| Solar | 太阳能 | Intermittent | 间歇性 | Falling; PV now competitive | 不断下降；光伏已具竞争力 | No power at night; weather-dependent | 夜间无电；依赖天气 |
| Wind | 风能 | Intermittent | 间歇性 | Moderate | 中等 | Visual and noise pollution | 视觉和噪音污染 |
| Hydroelectric | 水力 | Very high; controllable | 非常高；可控 | High initial; low running | 初始高；运行低 | Floods large areas; habitat destruction | 淹没大片区域；破坏栖息地 |
| Tidal | 潮汐 | Predictable | 可预测 | Very high | 非常高 | Disrupts marine ecosystems | 干扰海洋生态系统 |
| Geothermal | 地热 | Very reliable | 非常可靠 | High; site-specific | 高；受地点限制 | Only in volcanic areas | 仅限火山地区 |
| Biomass | 生物质 | Dispatchable | 可调度 | Moderate | 中等 | Competes with food production | 与粮食生产竞争 |
In extended-response questions, you may be asked to evaluate whether a particular resource is suitable for a given location. For example, a mountainous area with high rainfall would be excellent for hydroelectric power, while a flat inland region with low wind speeds would not be ideal for wind turbines. Always consider reliability, cost, environmental impact, and geographical suitability in your answers.
在扩展回答题中，你可能会被要求评估某一种资源是否适合特定地点。例如，降雨量大的山区非常适合水电，而风力低的平坦内陆地区则不适合安装风力涡轮机。在回答时，始终考虑可靠性、成本、环境影响和地理适宜性。
11. Efficiency, Energy Losses and Sankey Diagrams | 效率、能量损失与桑基图
In the exam, you may be asked to interpret or draw Sankey diagrams, which are scale drawings that show the energy input and output of a process. The width of each arrow is proportional to the amount of energy it represents. A Sankey diagram for a conventional power station would show a very thick arrow for the chemical (or nuclear) energy input, a moderately thick arrow for the useful electrical output, and several thinner arrows representing wasted heat and sound energy.
在考试中，你可能会被要求解读或绘制桑基图，这是一种按比例绘制的图，显示一个过程的能量输入和输出。每条箭头的宽度与它所代表的能量成正比。传统发电站的桑基图会显示一条很粗的化学（或核）能量输入箭头，一条中等粗细的有用电能输出箭头，以及几条较细的代表废热和声能的箭头。
To calculate the efficiency of a device or system, use the formula:
要计算设备或系统的效率，使用公式：
Efficiency = (Useful output energy ÷ Total input energy) × 100%
or, in terms of power:
或，以功率表示：
Efficiency = (Useful output power ÷ Total input power) × 100%
from the wind and produces 120 kW of electrical power, its efficiency is (120 ÷ 600) × 100% = 20% to rearrange the formula correctly: Useful output power = Efficiency × Total input power.
例如，如果风力涡轮机的风输入功率为 600 kW，产生 120 kW 的电功率，其效率为 (120 ÷ 600) × 100% = 20%。在扩展题中，你可能被给定额效率和其中一个功率值，并需要求出另一个。记住正确变换公式：有用输出功率 = 效率 × 总输入功率。
12. Key Exam Points and Revision Summary | 考试要点与复习总结
Below are the essential points you should remember for your Edexcel IGCSE Physics exam on energy resources and electricity generation.
以下是你参加 Edexcel IGCSE 物理考试时需要记住的关于能源资源和发电原理的要点。
Renewable resources will not run out; non-renewable resources will eventually run out. Know at least two examples of each and be able to explain why each is classified as such.
可再生资源不会耗尽；不可再生资源终将耗尽。要能举出至少两个例子，并能解释每种资源为何如此分类。
Fossil fuels release CO₂ and SO₂; nuclear power produces radioactive waste. Renewable resources produce little or no pollution but may have environmental or visual impacts.
化石燃料释放 CO₂ 和 SO₂；核电产生放射性废料。可再生资源几乎不产生污染，但可能有环境或视觉影响。
→ kinetic → electrical. In hydroelectric: gravitational potential → kinetic → electrical.
热力发电站的一般能量转换是：化学/核能 → 热能 → 动能 → 电能。水力发电：重力势能 → 动能 → 电能。
Step-up transformers raise voltage for transmission to reduce I²R losses. Step-down transformers reduce voltage for safe domestic use (230 V in the UK).
升压变压器提高电压以降低 I²R 损耗。降压变压器降低电压以保障安全生活用电（英国为 230 V）。
Efficiency = (useful output ÷ total input) × 100%. Always state both the formula and the calculated value with units.
效率 = (有用输出 ÷ 总输入) × 100%。始终写出公式和带单位的计算值。
Nuclear power provides very large amounts of energy per kilogram of fuel but produces long-lived radioactive waste and has high decommissioning costs.
核电每公斤燃料提供非常大量的能量，但产生长寿命放射性废料且退役成本高昂。
Renewable sources such as solar and wind are intermittent, whereas geothermal, tidal, biomass, and hydro are more reliable.
太阳能和风能等可再生能源具有间歇性，而地热、潮汐、生物质和水力更为可靠。
Energy resources are a rich and examinable topic because they connect physics with real-world environmental, economic, and political issues. By mastering the energy transfer chains, the classification of resources, the operation of the National Grid, and the efficiency calculations in this article, you will be well prepared for any question the examiner throws at you. Good luck!
能源资源是一个内容丰富且可考性强的主题，因为它将物理学与现实世界的环境、经济和政治问题联系起来。通过掌握本文中的能量转换链、资源分类、国家电网运行和效率计算，你将能够从容应对考官的任何一个问题。祝你好运！
Published by TutorHao | Physics Revision Series | aleveler.com
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