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How Does a Coal Power Station Work?
Coal power stations have powered much of the industrialized world for over a century. These large-scale facilities convert the chemical energy in coal into electrical energy, providing a stable and reliable electricity supply. While similar in function to other thermal power stations, coal-fired plants have distinct processes and environmental considerations.
Step-by-Step Overview of Operation
1. Fuel Handling and Preparation
Coal arrives at the power station by rail or conveyor systems. Before combustion:
Crushing: Large coal chunks are crushed into smaller, uniform particles.
Pulverizing: The crushed coal is ground into a fine powder, which allows it to burn more efficiently in the furnace.
2. Combustion in the Furnace
The pulverized coal is blown into a large boiler furnace where it is ignited:
High-Temperature Burn: The combustion process reaches temperatures over 1,500°C.
Energy Conversion: This chemical energy is converted into thermal energy.
3. Water-to-Steam Conversion
Running adjacent to the furnace is a system of high-pressure water pipes:
4. Turbine Activation
The force of the high-pressure steam spins the blades of a steam turbine:
The turbine is connected to a shaft, which drives the rotation of a generator.
This mechanical movement is essential for electricity generation.
5. Electricity Generation in the Generator
Inside the generator:
A rotating magnet moves within a coil of copper wire.
This induces an electric current through electromagnetic induction.
The resulting electricity is high-voltage alternating current (AC).
6. Cooling and Condensation
After leaving the turbine:
Steam enters a condenser, where it is cooled using water from cooling towers or nearby sources.
The steam condenses back into water and is pumped back into the boiler, completing the cycle.
Environmental Controls and Efficiency
1. Emissions Management
Coal combustion releases several pollutants:
Carbon dioxide (CO₂) – a major greenhouse gas.
Sulfur dioxide (SO₂) – leads to acid rain.
Nitrogen oxides (NOx) – contributes to smog and respiratory issues.
Particulate matter – fine ash particles harmful to health.
Modern plants use technologies like:
Flue Gas Desulfurization (FGD) – reduces SO₂.
Selective Catalytic Reduction (SCR) – limits NOx emissions.
Electrostatic Precipitators – capture fly ash particles.
2. Efficiency Enhancements
Older coal plants have efficiencies around 33%, but newer supercritical and ultra-supercritical designs reach efficiencies above 45%. These improvements reduce coal consumption and emissions per unit of electricity.
Advantages and Challenges
Advantages:
Stable Power Output: Reliable and consistent electricity generation.
Infrastructure: Extensive global coal infrastructure and supply chains.
Energy Storage: No need for energy storage systems unlike renewables.
Challenges:
Environmental Impact: High emissions compared to renewables and natural gas.
Water Usage: Requires large volumes of cooling water.
Aging Fleet: Many coal plants are decades old, with high maintenance needs.
Future of Coal Power
Globally, the use of coal is declining in favor of renewable energy and natural gas. However, in some regions, coal remains vital due to energy demands and resource availability. Efforts are ongoing to retrofit coal plants with carbon capture and storage (CCS) systems to mitigate environmental impact.
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