ENERGY
- energy sources
Energy sources (are natural resources from which we obtain different forms of energy that can be transformed for a specific use)
Household use
Industrial uses
By origin
By use in each country
By availability in nature and capacity for regeneration
By environmental impact
Renewable:
Non-renewable:
Abundant and inexhaustible
May or may not be abundant
Depleted when we use them up
Cannot be renewed in a short penod of time~
primary
secondary
Obtained directly from nature
Examples, crude oil, natural gas, coal, nuclear energy
and renewable energies
Resulting from transformation of pnmary sources
Examples; electnaty, some petroleum denvatives
conventional
Non-conventional
Most commonly used in mdustrialised countnes
Example energy that comes from fossil fuels
In early stages of their technological development
Solar and wind power belong to this group
Alternative energy sources
Clean or non-polluting:
Pollutants:
Low environmental impact
Don't generate by-products that pollute the environment
Sources that have negative effects on the environment,for example, they might generate by-products that severely pollute the enveronment
- electricity is the most widely used form of energy in industrialised societies for two reasons
It can be transported long distance
It can be easily transformed
2.1. Electric power plants are facilities where pnmary or secondary energy is transformed into electnmty, Once electricity is generated, it must be transported to towns, cities or industrial parks.
How an electric power plant works
The turbine converts mechanical energy into the rotating movement of a shaft
An alternator has a fixed part, called a stator, and a moving part,
called a rotor, connected to the turbine shaft
2.2. Transport and distribution of electrical energy Electric power plants are usually located far away from the points where the energy is used — fur safety reasons, space requirements or physical and geographical considerations Electricity cannot be stored; there fore, it must be transported to consumption centres This transport involves several processes:
Transporting it by high voltage cables attached to towers
Decreasing the voltage at the electncity substations to 3-30 kV
Increasing the voltage to 220 000 V or 400 000 V to significant energy loss, due to the Joule effect
Distribution to homes, offices, industnes and public faolities During this srage, the voltage is reduced to 230-400 V.
- Conventional electric power plants
3.2 Fossil fuel thermal power plants
3.1 Nuclear power plants this type of plant imcludes a nuclear fission reactor that produrces th pressunsed steam needed to move the turbme rotor. Uranium ts the main fuel used.
Combined cycle power plant
3.3. Hydroelectric power plants
Gravity-driven hydraulic power plants
Pump-driiven hydraulic power plants
- Non-conventional electric power plant.
The main disadvantage of these power plants is that they generate much less energy, since they use diffuse energy sources
The ir advantages are that they contaminate much less than
conventional power plants, they use renewable sources and they reduce the energy dependence of petroleum and natural gas.
4.1. Wind power plants and wind farms These power plants use the kinetic energy uf the wind to move the blades of a rotor at the top of a tower, this is referred to as the wind turbine. Wind farms are a clean form of generating electnmty However, they can only be instafled in plat.es with appropnate wind conditions.
4.2. Solar power plants
Photovoltaic power plant
Photo-thermal power plant
In this type of power plant, the heat generated by solar
radiation produces steam that is used to move the rotor in
the generator. To do this, they use special mirrors, called heliostats,that reflect sunlight and concentrate it at one point, where it reaches a high temperature
In these power plants, solar radiation is transformed directly into electncity by panels of photovoltaic cells.
4.3 Geothermal power plants
These plants use the heat found at deep levels in the earth. This heat may reach the surface in the form of steam, gases or hot water. Geothermal energy may be used directly — for hot water and heating, industnal use and so on — and indirectly — the heat generates steam, which produces electricity.
4.4. Biomass thermal power plants
Specific crops, such as sunflowers and cougar beet.
waste from agri-food industries.
Forestry and agricultural waste.
4.5. Ocean power plants
T he mechanical energy from the waves.
T he energy from the ocean's thermal gradient
The mechanical energy from the tides
- Environmental impact he building and operating of an ejectncai power plant results in an ecological change in that region This is due both to the construction of the necessary infrastructure and the waste that this activity generates.
5.1. Environmental impact assessment
As part of a technicaj proiect, it's mandatory to carry out an environmental impact assessment to find out what changes it would provoke in the environment An environmental study must also assess both the economic and social consequences of the project in the area, to decide whether or not to go
ahead with the plan. The main characteostii.s of each type of power plant and the impact they have on the environment are shown below
type of power plant
Hydroelectric
Solar
Fossil fuel thermal power plant
Wind power
Biomass
Environmental impact
Non recyclable waste pollutants
Atmospheric pollution from gas
Some lands are left underwate
Visual and sound impact
Non polluting
Beneficial if used correctly
Environmental changes resulting from required construoron work
Type of energy consumed
renewable
renewable
Non renewable
renewable
Non renewable
renewable
renewable
advantages
Great capacity and high performance
Clean
Great capacity and high performance
Possible production
Great capacity and high performance
Reduces dependence on other fuels
Clean, quiet
Disadvantages and risks
risk of disaster if a dam
low levels of performance
Risk of radioactive emissions
High installation costs
excessive exploitation of natural resources
High installation costs
5.2. Environmental impacts
Fuel transport
Electricity generation
Ex traction of natural resources
Final energy use
The exploitation of fossil fuels and nuclear power means the depletion of resources, which makes it necessary to find new ones Fuel extraction processes are sometimes harmful to the environment. In particular, timber extractron has led to the disappearance of large areas of forest, a process that is continuing even today.
Oil is transported by means of oil pipelines and oil tankers.
Oil pipehnes can suffer accidents caused by nature or human error, which result in uncontrolled spills. Oil tankers can have accidents at sea, with the nsk of oil spills. Some spills have caused oil slicks that have taken years to clean up and dissipate and have aftected the lives of many plant and animal species
Conventional thermal power plant
Nuclear thermal power plant
hydroelectric power plants
They emit large amounts of COa which increases rhe greenhouse effect.
They emit sulphur dioxide and nitrogen oxide that cause acid
rain, which is very harmful to the environment
The water used in the cooling system is returned to ihe environmem while it's sull warm, which affects both animal and plant life
They produce air pollution — suspended particles, CO, heavy
metal molecules and so on.
The fuels we use in vehicles and heating systems emit gases and particles similar to those generated by convenuonal thermal power plants. when we turn on an electric appliance, we' re consumrng energy that has already caused several environmental problems dunng its extraction, generation and transportation
5.3. Waste treatment
thermal power plants
nuclear power plants
Use coal with a low sulphur content, to reduce acid ram.
Ma intain and increase the size of large forested areas, since they absorb carbon dioxide.
Install special filters on the pipes at the power plant to capture some of the gas pollutants
5.4. Some solutions
Energy savings
Energy diversification
Efficiency
