Electricity Generation and Energy Conversion

• Electricity generation demonstrated through hand crank generators and a model steam turbine

Combustion Process

• The combustion process is chemically represented as: Fuel + O2 → CO2 + H2O
• Plant Scherer in Georgia uses this process

Electricity Production by a Generator

• Coal combustion heats a fluid
• Fluid (steam, water, or wind) rotates a turbine
• A turbine drives a generator
• The generator finally produces electricity

Energy Conversion in a Coal-Fired Power Plant

• Chemical energy from coal converts to thermal energy to produce steam in the boiler, which in turn becomes mechanical energy in the turbine
• The turbine results in electrical energy from the generator, which is then sent to users

Law of Conservation of Energy

• Energy is not destroyed but changed into other forms
• For example, 825 J of electrical energy in a hair dryer converts into 125 J of kinetic energy, 150 J of sound energy, and 550 J of thermal energy

Efficiency in Energy Conversion

• Second law of thermodynamics states energy degrades to low-quality waste heat and is lost to the environment with each conversion
• More efficient systems convert more fuel energy to useful energy

BTU and Calories

• Coal and natural gas possess chemical bond energy measured in BTU (British thermal units), convertible to calories
• 1 calorie is the energy needed to raise 1 gram of water by 1 degree Celsius
• 1 calorie = 0.00396573 BTU
• 1 BTU = 252 calories

Energy Efficiency Calculation

• Energy efficiency (E) is calculated as a percentage: E = (Energy Produced / Energy Consumed) x 100%

Efficiency Example: Coalville Power Plant

• The Coalville Power Plant generates 64,423 megawatt hours (64,423,000 kilowatt hours) of electricity by burning 31,796,825 metric tons (35,050 tons) of coal
• 1 kwh = 3413 BTU
• BTU value of coal = 9800 BTU/lb
• 2000 lb = 1 ton
• The plant's energy efficiency (E) equals 32%
• 68% of the energy in coal is lost as waste heat

Energy Efficiency as a Product of Individual Efficiencies

• The conversion of coal into light via an incandescent light bulb is only 1.6% efficient

System Efficiency Comparison

• Calculating the overall efficiencies of two systems reveals that power plants play a significant role
• Coal to electricity in power plants produces only 6% power
• Using natural gas produces 11%

Explore electricity generation through combustion, turbines, and generators. Understand energy conversion in power plants, focusing on how chemical energy transforms into thermal, mechanical, and finally, electrical energy. The Law of Conservation of Energy is also discussed.