Transcript Unit 51: Electrical Technology

Unit 51: Electrical Technology
The Characteristics and Principles of
AC and DC Generators and the
features of a Range of difference
Power Station
Course Aims
•
NDGTA
At the end of this course the learner will be
able to…
1. Know the methods used to produce electrical
energy
2. Know the properties and applications of conductors,
insulators and magnetic materials
3. Know the physical arrangements of supply,
transmission and distribution equipment
4. Know how electrical energy is used to support
applications of electrical technology
Agenda
NDGTA
• At the end of the session the learner will
be able to…
– Describe alternative electrical power
generation systems
Alternative
Electrical Power Systems
NDGTA
•
•
•
•
•
•
•
Solar power
Geothermal
Wind power
Magnetohydrodynamics (MHD)
Nuclear Fusion
Tidal
Biomass
Solar Power
NDGTA
• The sun generates heat by nuclear fusion. This heat is
radiated out into space and is available as a ‘free’ source
of energy.
• With fossil fuels becoming depleted, scientists are
exploring ways of harnessing this radiant energy.
• The amount of solar energy ‘hitting’ the Earth in the form
of sunlight and ultraviolet radiation in one day is
equivalent of burning millions of tons of coal. (It is
estimated that the amount of solar energy hitting the UK
in 1-hour is equivalent of the amount of energy needed
by the UK in 1-year!!)
Solar Power
NDGTA
• There are however a number of engineering
problems to be solving is solar power is ever to
be taken seriously as a useful source of energy.
These problems centre around converting,
controlling and using the solar energy.
• Essentially there are two methods for collecting
and concentrating solar energy: with the use of
parabolic mirrors and flat-plate solar collectors.
Solar Power:
Parabolic Mirrors
NDGTA
• These mirrors concentrate the energy of the sun
by focusing the light onto an opaque receiving
surface.
• If water could be made to circulate through
tubes, the heat focused onto the tubes could
turn the water into steam
• The steam could then be used to turn a turbine
to produce mechanical energy.
• The mirrors would need to be rotated to keep
them in the ‘best’ position to receive the sunlight.
Solar Power:
Flat-plate Solar Collector
NDGTA
• Layers of glass are laid over a blackened
metal plate, with an air space between
each layer.
• The layers act as a heat trap: they let the
rays of the sun in but keep most of the
heat from escaping. The heated air could
then be used to warm a home.
Solar Power:
Issues
NDGTA
• Currently very inefficient.
• Environmental impact of large arrays of
parabolic mirrors or solar plates: villages in
France; fields in Usk.
Geothermal Systems
NDGTA
• This relies on the heat generated by the core of
the Earth. The effects of this geothermal activity
can be seen with volcanoes or geysers.
• The systems requires the boring of a hole or
holes. These can be many miles deep (10miles)!!
• Water is then entered into one of the holes and it
returns to the surface as steam which could be
used to generate electrical energy.
Geothermal Systems
• Issues:
– environmental impact of drilling
– The corrosive effect of the water under
pressure in the pipes.
– Plate tectonics
NDGTA
Wind Systems
NDGTA
• Wind power is non-polluting, inexpensive
power system.
• Its major drawback is that it only
generated electricity when there is
sufficient wind to turn the blades. Thus it
is a very inefficient way of generating
electricity.
• It has a large environmental impact – note
the devastation of the Welsh countryside!!
Nuclear Fusion
Systems
NDGTA
• There are several methods that are being
investigated
– Magnetic-confinement
– Laser induced fusion
• The problem with nuclear fusion is that it
currently takes more energy to produced the
fusion reaction that then reaction generates
itself. This is because of the length of time the
reaction takes place – literally only fractions of a
second – i.e. the reaction is not-self sustaining.
Other Systems
NDGTA
• Explore the following making and make
your own notes on how the electrical
power is generated and the impact each
has on the environment.
– Tidal power systems
– Fuel cells
– Magneto Hydrodynamic systems
– Biomass systems
– Oil-shale production systems