Calculating SO2 Emissions from a Coal Power Plant

This problem requires us to calculate the daily emission of sulfur dioxide (SO2) from a coal-based power station given its capacity, efficiency, the sulfur content in the coal, and the energy density of the coal.

Understanding the Given Parameters

We are provided with the following information about the coal power station:

• Power station capacity: 500 MW
• Operating efficiency: 30%
• Sulfur content in coal: 1% by weight
• Energy produced per tonne of coal: 8000 kWh/tonne

We need to find the total amount of SO2 emitted daily.

Step-by-Step Calculation of SO2 Emission

Step 1: Calculate the total energy output of the power plant per day.

The plant operates at a capacity of 500 MW. We need to find the energy produced in 24 hours.

Capacity = 500 MW

Daily operating time = 24 hours

Total daily energy output = Capacity \(\times\) Time

First, convert MW to kW (since energy density is in kWh):

\(500 \text{ MW} = 500 \times 10^3 \text{ kW}\)

Daily Energy Output (kWh) = \(500 \times 10^3 \text{ kW} \times 24 \text{ hours}\)

Daily Energy Output = \(12,000,000 \text{ kWh}\)

Step 2: Calculate the total energy input required from coal based on the plant's efficiency.

The plant has an efficiency of 30%. This means that for every unit of energy input from coal, only 30% is converted into electrical energy output.

Efficiency \(= \frac{\text{Energy Output}}{\text{Energy Input}}\)

Energy Input \(= \frac{\text{Energy Output}}{\text{Efficiency}}\)

Daily Energy Input from coal = \(\frac{12,000,000 \text{ kWh}}{0.30}\)

Daily Energy Input from coal = \(40,000,000 \text{ kWh}\)

Step 3: Calculate the daily amount of coal consumed.

We know that 1 tonne of coal produces 8000 kWh of energy.

Daily Coal Consumption = \(\frac{\text{Daily Energy Input}}{\text{Energy per tonne of coal}}\)

Daily Coal Consumption = \(\frac{40,000,000 \text{ kWh}}{8000 \text{ kWh/tonne}}\)

Daily Coal Consumption = \(5000 \text{ tonnes}\)

Step 4: Calculate the total amount of sulfur consumed daily.

The coal has a sulfur content of 1% by weight.

Daily Sulfur Consumption = Daily Coal Consumption \(\times\) Sulfur Content

Daily Sulfur Consumption = \(5000 \text{ tonnes} \times 0.01\)

Daily Sulfur Consumption = \(50 \text{ tonnes}\)

Step 5: Calculate the daily emission of SO2.

When sulfur (S) burns, it reacts with oxygen (O2) to form sulfur dioxide (SO2).

The chemical reaction is: \(S + O_2 \rightarrow SO_2\)

The molecular weight of Sulfur (S) is approximately 32 g/mol.

The molecular weight of Sulfur Dioxide (SO2) is approximately 32 (for S) + 2 \(\times\) 16 (for O) = 64 g/mol.

From the reaction, 1 mole of S produces 1 mole of SO2. By mass, 32 units of mass of S produce 64 units of mass of SO2. This means the mass of SO2 produced is double the mass of sulfur burned.

Mass of SO2 emitted = Mass of Sulfur consumed \(\times\) 2

Daily SO2 Emission = \(50 \text{ tonnes} \times 2\)

Daily SO2 Emission = \(100 \text{ tonnes}\)

Thus, the power plant will emit 100 tonnes of SO2 daily.

Revision Table: Coal Power Plant Emissions

Reviewing the steps involved in calculating SO2 emissions from a coal power plant:

• Start with the plant's electrical output capacity and operating time to find total energy produced daily.
• Use the plant's efficiency to determine the total energy input required from the fuel (coal).
• Use the coal's energy content (kWh/tonne) to calculate the daily coal consumption in tonnes.
• Apply the coal's sulfur content percentage to find the total mass of sulfur burned daily.
• Use the stoichiometric ratio from the combustion of sulfur to SO2 (S to SO2 is 1:2 by mass) to calculate the total mass of SO2 emitted daily.

Additional Information: Environmental Impact of SO2 Emissions

Sulfur dioxide (SO2) is a major air pollutant produced primarily from the burning of fossil fuels, especially coal, that contain sulfur. It has significant environmental and health impacts.

• Acid Rain: SO2 reacts in the atmosphere to form sulfuric acid, a major component of acid rain. Acid rain can damage forests, lakes, and buildings.
• Respiratory Problems: SO2 is a respiratory irritant and can cause breathing difficulties, particularly for individuals with asthma and other respiratory conditions.
• Particulate Matter: SO2 can contribute to the formation of fine particulate matter in the atmosphere, which is linked to various health issues.
• Vegetation Damage: High concentrations of SO2 can directly damage the leaves of plants.

Power plants often use technologies like Flue Gas Desulfurization (FGD), also known as "scrubbers," to remove SO2 from the exhaust gases before they are released into the atmosphere, reducing their environmental impact.