Important Notes
Hydropower:
The principle involves the transformation of potential energy stored in water at a height into kinetic energy as it descends, propelling turbines that are linked to generators.
Categories:
- Impoundment: By building reservoirs, big dams regulate the flow of water.
- Run-of-River: Smaller, use rivers’ natural flow while storing less.
- Pumped storage: When there is less demand, energy is stored by pushing water uphill.
Important variables include turbine efficiency, flow rate, and available head (height differential).
Tidal Energy
Principle: Utilises the kinetic energy of tidal currents generated by the sun’s and moon’s gravitational pull.
Categories:
- Barrage: Estuarine dams equipped with turbines that are triggered by variations in tidal flow.
- Tidal Stream: Rapidly moving currents are converted into energy by underwater turbines.
The challenges include high starting costs, environmental impact on marine ecosystems, and intermittency.
Conversion of Ocean Thermal Energy (OTEC):
The idea is to create energy by using the temperature differential between warm surface water and cold deep water to power a heat engine (Rankine cycle).
Categories:
- Closed-Cycle: Heating working fluid (such as ammonia) to a boiling point, which powers a turbine before condensing with cool water.
- Open-Cycle: Steam is produced by flash-evaporating warm saltwater, which powers a turbine.
The challenges include potential environmental effects, significant upfront expenditures, and technological complexity.
Wind Energy
Principle: Uses wind turbines to transform wind energy from kinetic to mechanical form, which powers generators.
Important factors include turbine size, blade design, and wind speed (and its cubic connection to power).
Categories:
Onshore: Terrestrial wind farms.
Offshore: Wind farms located in aquatic bodies, frequently with more constant and powerful winds.
The challenges include noise, visual impact, intermittency, and possible injury to birds.
Geothermal Power:
The idea is to use the heat that exists inside the Earth to power turbines by extracting it as steam or hot water.
Categories:
- Hydrothermal: Makes use of naturally existing steam or hot water reservoirs.
- Enhanced Geothermal Systems (EGS): To produce artificial reservoirs, water is injected into hot, dry rock.
- Geothermal heat pumps: These systems use the steady temperature of the earth to provide heat and cold.
Challenges include expensive upfront costs, the possibility of induced seismicity, and a shortage of suitable places.
Solar Power:
The idea is to absorb solar radiation and transform it into either heat or electrical power.
Categories:
1. Thermal Sunlight:
Solar collectors: They gather solar radiation to heat air or water for usage in homes or businesses.
Solar Ponds: Salinity-gradient saltwater ponds designed to retain solar heat.
2. Solar Photovoltaic (PV): PV Modules: Direct conversion of sunlight into electricity using semiconductor materials (silicon).
Solar Energy: Detailed Technologies
- Flat plate solar collectors are easy to use, reasonably priced, and appropriate for temperatures ranging from low to medium.
Evacuated tube collectors: Higher efficiency, perfect for high-temperature applications. - Photovoltic Modules:
Monocrystalline: Expensive, high efficiency.
Polycrystalline: More economical, but less efficient.
Thin-Film: New technology, flexible, lightweight, and less efficient. - Solar Ponds:
Non-Convecting: Bottom layer becomes extremely heated, and salt gradient hinders mixing.
Convecting: Used to heat spaces, it involves some mixing and a smaller temperature gradient.
