Learn about Energy, energy sources and the consequences of using energy

1. Energy and its
transformations
Tecnology 3rd ESO

2. Index
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Definition
Types of energy
Electricity
Power stations
Energy efficiency

3. What is energy?
• We define energy as the capacity of performing any activity.
The Junits of energy are: J(joule), cal (4,15 J),
kw·h(1000J/s*3600s=3 600 000 J)
• We define power as the capacity of performing work in a unit of
time: P=Energy produced or consumed / time
Units for power: W (watt), kW, CV or hp (1 C.V. = 735,5 W)
Index

4. Types of energy
Renewable?
Origin
Renewable
Non Renewable
Wind
Hydroelectric
SUN
Fossil fuels
Coal
Photovoltaic,
sun thermal
Seas
Gas
Oil
Biomass
EARTH
SUW (RSU)
Nuclear
Geothermal
fuels
Index

5. Electricity
Electricity is an extremely
useful form of
electricity because:
1. It is easy to produce
and transform
2. It is easy to transport
Electricity is produced in
power stations, which
can be: Thermal,
hydroelectric, wind
farms, solar cells…

6. Production of electricity
To produce energy we use an
alternator formed by
• A turbine which rotates debt
to other energy(wind, water
vapour)
• A generator, formed by a
rotor connected to the
turbine and an stator.
Bobines are holed along the
stator and magnets
conductors along the rotor.
The movement of the rotor
induces the production of a
voltage, and thus electricuty,
on the stator
Index

7. Thermal stations
• Thermal stations generate vapour at high pressure) to
push the turbine blades of the alternator. Normally
fossil fuels (coal, gas-oil, gas) are burnt to generate
vapour
• They are pollutant, non renewable, but very effective

8. Nuclear power stations
• Nuclear power station are thermal stations where
the vapour is generated with the heat from
nuclear reactions: Uranium, plutonium
• They are pollutant, non renewable, but very
effective

9. Hydroelectric station
• Sun evaporates water from seas. This provoques
rain and craetes rivers, whose water is stored
with dams. The energy of this water is used to
generate electricty
• This is renewable, non pollutant but also destroys
valleys and depends on the climate.

10. Wind farms
• Wind farms are groups of aerogenerators, placed over
mountain tops, which convert wind into electricity. The
devices use a huge turbine(fan) of 60 m (diameter)
• This energy is renewable, non pollutant and quite reliable,
for wind is countiuous over muntains. The pollution is visual.
The generators can be dangerous for certain birds

11. Sun cells
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•
•
Sun rays release the
electrons of certain metals
when they hit them. This
produces a flow of charges:
Photovoltaic effect
This energy is renewable and
non pollutant, but the
materials for procing sun cells
are extremely pollutant and
the effiency is low
This energy is used to support
conventional electricity supply
or when it is impossible to
connect to the electric grid
(satellites)
Index

12. Distribution of energy
• Distribution of electricity
• Distribution of fuels

13. Distribution of
electricity
Electricity is produced in power station far away from citis or industries
(consumption centres)
• We use a grid to transport electricity.
• Two kinds of grid are used: Transport and distribution grid
• To diminish the amuont of power wasted because of the resistance of the
wire, (Pw=R·I2), tension is extremely high, so I is very low (I=Pd/V).
• High tension is only available in the transport grid. The distribution grid,
which brings electricity to houses and industries is transformed to lower
values to help electrical accidents (fires, explosions)

14. Distribution of fossil
fuels
• Coal is produced in
mines and oil and gas
are found underground
(oil wells)
• Coal is distributed
with ships, trains or
lorries to the
cosumption centres
• Gas and oil are
distributes with ships
or pipes

15. Energy effiency
• Energy production and
consumption is harmful for the
enviroment (it is pollutant, and
spends a lot of resources).
• We define efficiency as
Efficiency=Converted
energy/Consumed energy
• The most efficient a device is, the
better for our enviroment and for
ourselves
Index