Please enable JavaScript.

Coggle requires JavaScript to display documents.

Unit 8- ENERGY AND ITS TRANSFORMATION, image, image, image, image, image,…

- - - - we can classify energy sources in several ways
        
        By availability in nature and capacity for regeneration
        
        By origin
        
        By use in each country
        
        By environmental impact
- - - - How an electric power plant works
        
        Electncal power plants use an external source of energy to produce
        electricity To do this, they rely on a turbine-alternator system.
        
        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
  - - - Electncity cannot be stored; therefore, it must be transported to
        consumption centres
        This transport involves several processes:
        
        Increasing the voltage to 220 000 V or 400 000 V to prevent signifcant energy loss, due to the Joule effect
        
        Transporting it by high voltage cable attached to towers
        
        Decreasing the voltage at the electncity substations to 3-30 kV
        
        Distribution to homes, offices, industries and public facilities. During this stage, the voltage is reduced to 230-400 V.
- - - - This type of plant includes a nuclear fission reactor that produrces the
        pressurised steam needed to move the turbine rotor.
        
        Uranium is the main fuel used.
        
        Their main advantage is the high return on their energy production
    - - At this type of power plant, water is heated in a boiler by the heat
        generated from the combustion of a fossil fuel, usually natural gas or coal
        
        The steam that's generated moves the turbine connected to the generator
      - Combined cycle power plant
        
        Efectricity ts generated as a result of two combined cycles, a cycle that uses air and gas, and a conventional thermal cycle. During the first cycle,a gas turbine is used that includes a compressor.
        
        Air is mixed with the gas and is burnt, which generates electncity
        in the turbine-alternator system. The combustion gases are transported
        to a boiler, where they transfer their energy to the water during the second
        cycle
    - - This type of power plant uses the potential energy provided by the
        height of the stored water in a dam, converting it into kinetic energy.This energy moves the blades of the turbine
        
        Depending on the destination of the water, hydraulic power plants are
        divided into two types, gravity or pump.
- - - - .
        
        The amount of power generated depends on the size of the installation
        but it's usually between 1 MW and 10 MW.
  - - - 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,
        steam that reflect sunlight and concentrate it at one point, where it reaches a high temperature
      - Photovoltaic power plant
        
        In these power plants, solar radiation is transformed directly into
        electncity by panels of photovoltaic cells.
  - - - • Forestry and agricultural waste
      - • Specific crops, such as sunflowers and sugar beet.
        
        Biomass Is subjected to different physical and chemical processes in order to produce fuel such as charcoal, alcohol or biogas. This type of fuel is burnt at biomass power plants. The steam that is generated moves the turbine.
      - • Waste from agri-food industries.
  - - - • The mechanical energy from the tides.
        • The mechanical energy from the waves.
        • The energy from the ocean's thermal gradient.
        
        These power plants are still in the experimental phase and their level of
        production is still very low.
- - - - Extracction of natural resources
        
        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 water particular, timber extractron has led to the disappearance of large areas of
        forest, a process that is continuing even today.
        
        Fuel transport
        
        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
        
        Electricity generation
        
        Large hydroelectric power plants require water reservoirs covenng large areas, which protoundly change the natural cycle of overs,
        flood large land areas and destroy ecosystems, in addition to
        increasing the risk of accidents.
        
        Conventional thermal power plants can cause numerous problems
        and environmental hazards
        
        • They produce air pollution — suspended particles, CO,heavy
        metal molecules and so on.
        
        • They emit large amounts of CO2 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
        
        Nuclear thermal power plants are accompanied by the risk of
        nuclear accidents and the problem of nuclear waste, some of which
        Large dams profoundly change the natural remaim dangerous for thousands of years
        
        Final energy use
        
        The fuels we use in vehicles and heating systems emit gases and
        particles similar to those generated by conventional thermal power plants.
        When we turn on an electric appliance, we' re consuming energy that
        has already caused several environmental problems dunng its extraction,
        generation and transportation.
    - - .
        
        • To reduce the waste generated by thermal power plants, as well as their effects, several measures can be taken
        
        • Install special filters on the pipes at the power plant to capture some of the gas pollutants
        
        • Use coal with a low sulphur content, to reduce acid rain
        
        • Maintain and increase the size of large forested areas, since they absorb carbon dioxide.
        
        • Waste from nuclear power plants is stored in drums with thick
        sides that do not let the nuclear radiation escape These are then
        stored in ocean trenches and underground.
        
        The use of ocean trenches has its own problems, because there's the risk
        of the drums corroding and the radioactive matenal leaking out of them
      - 5.4. Some solutions
        
        .
        
        Below is a summary of different possible solutions to alleviate some of
        the environmental problems described