The correct answer is: a) Coal.
Coal is the primary fuel used in thermal power plants in Tamil Nadu. In 2019, coal accounted for 86% of the total electricity generated in the state from thermal power plants. Lignite, natural gas, and hydropower are also used to generate electricity in Tamil Nadu, but to a lesser extent.
Coal is a fossil fuel that is formed from the remains of ancient plants and animals. It is a non-renewable resource, meaning that it cannot be replaced once it is used up. Coal is a major source of greenhouse gas emissions, which contribute to climate change.
Lignite is a type of coal that is lower in quality than bituminous coal or anthracite coal. It is also known as brown coal. Lignite is found in abundance in Tamil Nadu, and it is the second most important fuel used in thermal power plants in the state.
Natural gas is a fossil fuel that is formed from the remains of ancient plants and animals. It is a cleaner-burning fuel than coal, and it produces fewer greenhouse gas emissions. Natural gas is also a more efficient fuel than coal, meaning that it produces more electricity per unit of fuel.
Hydropower is a renewable energy source that uses the power of moving water to generate electricity. Hydropower is a clean and efficient source of energy, and it does not produce greenhouse gas emissions. However, hydropower projects can have a negative impact on the environment, such as by disrupting fish migration and altering water flows.
In conclusion, the thermal power plants in Tamil Nadu primarily utilize coal. Coal is a non-renewable resource that is a major source of greenhouse gas emissions. Lignite, natural gas, and hydropower are also used to generate electricity in Tamil Nadu, but to a lesser extent.