Power Generation Methods: Hydro, Thermal, and Nuclear Plants
Power Plants:
Hydroelectric plants leverage the power of water, converting it into electrical energy. There are two main types:
- Central Water Gushing: (Utilizing kinetic energy) Built in locations with strong water currents to drive turbines, these facilities have limited applicability.
- Central Water Flooding: (Utilizing potential energy) Water is stored in a reservoir and used as needed to generate electricity. This type has two models:
- Central Shunt: The river is diverted through a small dam into a channel with a minimal slope.
- Accumulation Centers: Located on a river stretch where a dam creates a reservoir.
Dam: A concrete structure built across a river to create a reservoir.
- Gravity Dams: The water’s force is countered by the dam’s weight. A variant involves building buttresses to save on material costs.
- Arch Dams: Curved in shape, these dams transmit the water’s force into the surrounding rock, requiring less material.
Water Management: Gates and valves control the water flow, allowing for water release without passing through the turbines.
Engine Room: Houses the turbo-alternators. Different turbine types are used depending on the height of the water drop and flow rate:
- Pelton Turbines: High head, regulated flow.
- Francis Turbines: Medium head, variable flow.
- Kaplan Turbines: Low head, variable flow.
Transformers and Distribution: Transformers increase voltage for efficient transmission to consumers. The distribution network connects to the transmission grid via high-voltage lines. Most power stations are interconnected and synchronized.
Hydroelectric Plant Operation: The dam creates a reservoir. Water flows through a penstock to the turbines in the powerhouse at the dam’s base. Potential energy converts to kinetic energy as the water flows through the turbines, driving the generator. The generated electricity’s voltage is increased by transformers for transmission.
Reversible Pumped Storage: These plants optimize energy production based on demand. During peak demand, water flows from an upper reservoir to generate electricity. During low demand, excess electricity pumps water back to the upper reservoir.
- Pure Pumping: Relies solely on pumped water for generation.
- Mixed Pumping: Can also generate power from river flow.
Mini-Hydro: Small-scale plants (250-500kW) often used in rural areas.
Hydroelectric Plants and the Environment:
Advantages: Flood control, regulated river flow.
Disadvantages: Impact on vegetation and wildlife.
Thermal Power Plants: Generate electricity by burning fossil fuels (coal, oil, or natural gas). Steam turbines are used to generate electricity.
Thermoelectric Plant Components: Fuel storage, boiler, turbine, condenser, cooling tower, chimney, and electrical equipment.
Plants designed for multiple fuels are called mixed plants.
- Boiler: Vaporizes water using heat from fuel combustion.
- Reheaters: Remove water droplets from steam.
- Pre-heaters/Economizers: Utilize waste heat from exhaust gases.
- Turbines: Convert steam’s kinetic energy into rotational energy.
- Condenser: Cools and condenses steam from the turbine.
- Cooling Tower: Cools the condenser water.
- Chimney: Creates draft for combustion gases.
- Electrical Equipment: Alternator, transformers, and distribution network.
- Water Treatment: Prevents sludge formation and maintains pH levels.
Thermoelectric Plant Operation: Coal is crushed into powder, mixed with hot air, and injected into the boiler. Water in the boiler tubes turns to steam, which drives the turbine and generator. The steam is then condensed and returned to the boiler. Exhaust gases are used to preheat combustion air.
Thermal Power Plants and the Environment: CO2 emissions, air pollution, and noise pollution.
Combined Cycle Power Plants: Utilize both gas and steam turbines. A gas turbine drives a generator and its exhaust gases heat a boiler, producing steam for a steam turbine, which also drives a generator.
Cogeneration Plants: Produce both electricity and heat. Modules can be based on gas turbines or diesel engines.
Nuclear Power Plants: Thermal power plants using nuclear fission as a heat source.
Nuclear Reactor: The core component of a nuclear power plant, enabling controlled chain reactions.
Reactor Components:
- Reactor Vessel: Contains the nuclear fuel.
- Moderator: Slows down neutrons to sustain the chain reaction.
- Control Rods: Regulate the fission rate.
- Cooling System: Removes heat from the reactor.
Types of Nuclear Power Plants:
- Pressurized Water Reactor (PWR): Uses water as both coolant and moderator.
- Boiling Water Reactor (BWR): Water serves as coolant and boils within the reactor.
Nuclear Facility Buildings: Containment building, turbine building, fuel building, control building, and auxiliary building.
Nuclear Power Plant Operation: Heat generated in the reactor core is transferred to a coolant, which then heats water in a steam generator. The steam drives a turbine connected to a generator. The steam is condensed and returned to the steam generator. Cooling water for the condenser typically comes from a river or sea.
Nuclear Power Plants and the Environment: Require highly trained personnel, anomaly detection systems, and environmental monitoring.