Thermal electricity (electric power generated in thermal power plants) is generally produced by using which of the following fuels?

Introduction / Context:
Thermal power plants generate electricity by converting heat energy into electrical energy. The heat is usually produced by burning fuels to make steam, which then drives turbines connected to generators. This question examines your understanding of which fuels are commonly used for generating thermal electricity in power stations, especially in the context of fossil fuels that are widely mentioned in geography and general science.

Given Data / Assumptions:

• The focus is on fuels used in thermal electricity generation.
• The options mention coal, natural gas, and petroleum in different combinations.
• We assume conventional thermal power, not nuclear or solar thermal plants.

Concept / Approach:
In most countries, especially developing ones, thermal power plants primarily burn fossil fuels such as coal, petroleum products (like furnace oil or diesel in some plants), and natural gas. These fuels heat water in boilers to produce high pressure steam that turns turbines. Coal is historically the dominant fuel, but natural gas and oil fired plants are also widely used. The correct answer should include all three major conventional fossil fuels used in thermal power generation, rather than limiting the list to only coal or only two of them.

Step-by-Step Solution:
Step 1: Consider coal. It is the most common fuel for thermal power plants, especially in countries with large coal reserves. Step 2: Consider natural gas. Many modern power stations, including combined cycle plants, use natural gas because it burns cleaner and can be more efficient. Step 3: Consider petroleum. Oil, in the form of heavy fuel oil or diesel, can be used in some thermal power plants and in smaller generators, especially where gas or coal is less available. Step 4: Option A includes only coal, which overlooks gas and petroleum based plants. Step 5: Option B includes coal and natural gas but leaves out petroleum, which is also a valid thermal fuel. Step 6: Option C, which lists coal, natural gas, and petroleum, correctly includes all main fossil fuels used in conventional thermal power plants.

Verification / Alternative check:
Energy statistics and power plant descriptions typically classify thermal power plants as coal fired, gas fired, or oil fired stations. Some plants can switch between oil and gas. Although coal dominates in many regions, the use of oil and gas is well documented. Nuclear and renewable sources are usually categorised separately and are not considered part of fossil fuel thermal generation in this simple classification. This confirms that all three listed fossil fuels in option C are used to generate thermal electricity.

Why Other Options Are Wrong:

• Coal only: Ignores the significant number of gas and oil fired thermal stations and is therefore incomplete.
• Coal and natural gas only: Leaves out petroleum based fuels, which are also used in some thermal plants and backup generators.
• None of these: Incorrect because the listed fuels are precisely those used in conventional thermal power generation.

Common Pitfalls:
Some learners associate thermal electricity only with coal because of its large share in certain national power mixes. Others may think natural gas is used only in cooking or industry, forgetting that many power plants are gas based. Confusion can also arise if nuclear plants are thought of as thermal plants, but those use nuclear fuel rather than fossil fuel. To answer correctly, remember that coal, petroleum, and natural gas are the three major fossil fuels, and all are used in thermal power generation.

Final Answer:
Thermal electricity is commonly generated using coal, natural gas and petroleum as fuels.