Fossil Fuels
- examples: Petroleum, natural gas, wood, coal
- Fossil fuels have energy in the chemical potential stores
- when fuel is burnt in air for cooking food, heating transfers energy from chemical potential store of the fuel to the internal stores of the good and surroundings.
Advantages
- more reliable than other resources as fossil fuels do not depend on environmental factors.
- relatively cheaper cost of production compared to other resources.
Disadvantages
- Non renewable energy resource
- environmental pollution from the gasses produced during burning contributes to global warming.
Nuclear Fuels
- nuclear fuels - undergo nuclear reactions to release energy. Most nuclear fuels such as uranium undergo a nuclear reaction called nuclear fission.
- During nuclear fission, nuclei of uranium splits into 2 or more moving parts. This in turn raises temperature of the water surrounding the fuel rods to produce steam.
- electrical power is generated when steam moves the turbines in the nuclear power station.
Advantages
- low carbon energy resource that helps to reduce greenhouse gas emissions that cause global warming
- Higher reliability in supplying uninterrupted power
Disadvantages
- Non renewable energy resource
- Risk of accidents and pollution from the improper disposal of radioactive waste.
Biofuels
- Examples; ethanol, biodiesel, biogas, which are derived from biomass. Biomass comes from living materials such as corn and animal manure
- Biofuels have energy in the chemical potential store.
- when cooking, heating transfers energy from chemical potential store of the biofuel to the internal store of the food and surroundings.
Advantages
- Renewable energy resource
- Widely available on large scale
- relatively cheaper cost of production compared to other resources.
Disadvantages
- Environmental pollution from gasses produced during burning contributes to global warming
Wind
- Energy in the kinetic store of wind is transferred mechanically to the kinetic store of rotor blades of the wind turbines
- Electrical power is generated when roto bladed connected to the generators rotate.
Advantages
- Renewable energy resource.
- Clean method of producing electricity (no harmful gasses produced)
Disadvantages
- intermittent power as it is not as easy to find places where there is steady wind blowing at speed of 20-25km/h
- Noise pollution and loss of habitat for wildlife as land is cleared to build wind turbines.
Tides
- Water movement from changing high and low tides causes turbines below water surface to rotate
- Energy in the kinetic store of the water is transferred mechanically to kinetic store of turbines.
- Electrical power is generated when turbines connected to generators rotate.
Advantages
- Renewable energy resource
- More reliable than wind or the sun
- Clean method of producing electricity
Disadvantages
- high cost of building tidal barrages, turbines and generators.
- marine life affected due to alterations of water currents, noise and emission of electromagnetic fields.
Hydropower
- obtained from water behind hydroelectric dams.
- water behind hydroelectric dams has energy in the gravitational potential store. by releasing water and letting it flow downwards, energy in the gravitational potential store is transferred mechanically to the kinetic store of water.
- flowing water causes turbines to spin. electrical power is generated when turbines connected to generators rotate.
Advantages
- Renewable energy resource as the water movement can be continually regenerated
- clean method of producing electricity
Disadvantages
- high cost of building dams, turbines and generators.
- Possible damage to the environment surrounding the river caused by damming of river for hydroelectric power station.
Geothermal reservoirs
- in certain areas, such as volcanic regions, geological forces push large amount of hot molten rocks near the earths surface. these places are known as geothermal hotspots.
- water than makes its way to these geothermal hotspots is heated and subjected to great pressure.
- this heated water has a large amount of energy in the internal store. the water is forced to the surface as boiling water and steam to drive turbines.
Advantages
- Renewable energy resource
- Clean source of naturally available energy in the internal stores.
Disadvantages
- environmental pollution caused by release of poisonous gasses such as hydrogen sulfide into the atmosphere.
- Not widely available as they are found only in certain areas around the world.
Solar Power
- comes from sun. sun has energy in the nuclear store.
- energy in the nuclear store of the sun is transferred by electromagnetic waves from the sun to the internal store of the solar panels.
- solar panels compromise many individual solar cells. each cell is made of semiconductors such as silicon. When solar panels are irradiated by sunlight, electricity is generated.
Advantages
- renewable energy resources
- clean method of producing electricity
Disadvantages
- Not always available as there is no sunlight at night, and it is weather dependent.
- Solar panels or collectors take us a lot of space.
Efficiency of energy transfer for electricity generation in fossil fuel power plants → is about 32% (in coal plants) to 45% ( in natural gas plants). Average efficiency of energy transfer for electricity generation in nuclear power plants is about 33%, which is comparable to thats of the coal power plants
Efficiency of energy transfer for electricity generation using hydropower and tides is higher than that of fossil fuel power plants. efficiency of energy transfer for electricity generation using biofuels, wind, geothermal reservoirs and solar power is less than that of fossil fuel power plants.
important to note: that efficiency of energy transfers for electricity generation depends on technologies employed. improvements in technologies → can improve efficiency of energy transfer for generating electricity. ++ efficiency of energy transfer for electricity generation is dependent on different factors such as types of fuels, location and weather. thus → efficiency of energy transfer differs across different power plants and locations even though the plants and locations may use same type of energy resource for electricity generation.