Sujet-2

University of Mohamed–Seddik Ben Yahia –Jijel
English/ Electrical Engineering / undergraduate (2nd year) Homework
1
ENVIRONMENTAL IMPACT OF ELECTRICITY GENERATION
All energy conversion methods used to produce electricity have some environmental
impact. The impact may have an active effect like the emission of airborne pollutants, or may
have a passive effect like aesthetics or habitat modification. Even methods considered
environmentally friendly have some impact on the environment. Fossil fuel power plants
generally have the most widespread effect on the environment, as the combustion process
produces airborne pollutants that spread over a wide area. Nuclear power plants have the most
potentially dangerous effect. An operating accident at a nuclear station could allow for a large
release of radioactive particles to occur. Solar, hydro, and wind power plants generally have
smaller effects on the environment.
The whole cycle of electricity generation must be considered when looking at the
environmental impact. This includes the production and transportation of fuel for the
conversion process. This is especially true of fossil fuel and nuclear power plants, which use
large quantities of fuel mined from the earth. Energy system environmental impact consists of
fuel recovery and production, fuel transportation, electricity transmission, and spent fuel
emissions.
The generation of electricity from solar energy sources generally has a small effect on the
environment. There are no residuals produced in the energy conversion process. The use of
hydropower to produce electricity can have both positive and negative effects on the
environment. Wind generators biggest environmental effects come from visual pollution,
noise, and TV interference.
The heat generated by an electric-power plant that is not ultimately converted into
electrical energy is called waste heat. The environmental impact of this waste is potentially
catastrophic, especially when, as is often the case, the heat is absorbed by streams or other
bodies of water. Cooling towers help to dispose waste heat into the atmosphere.
I. Answer the following questions
1. Why are the nuclear power plants considered to be the most dangerous?
2. Give a scientific description of the underlined words.
3. What are the active and passive environmental effects of the energy conversion methods?
4. What is the bad effect of an Electric Power Plant?
5. Cite renewable energies mentioned in the text.
6. Explain in few lines the basic principle of solar energy conversion.

University of Mohamed–Seddik Ben Yahia –Jijel
English/ Electrical Engineering / undergraduate (2nd year) Homework
2
II. Write : another, other, the other, others.
1. I met two strangers on the way to work. One of them greeted me and…………..didn’t .
2. Some people like to have the windows open all the time;…………….don’t.
3. I can't see him today. I'll have to see him ..……..…..day.
4. There must be …………... solution to solve the problem.
5. There must be.................... roads that lead to the city center.
III. Complete the statements with the appropriate word.
deplete – destroy – depletion –solve – destruction – depletable –demand– produce – depleted
– destructive – solution – productivity
1. Ozone …………is the human destruction of the ozone layer. This can come from greenhouse gases,
given off by factories, cars, and electricity usage.
2. Our supplies of food are rather ……………. If we continue to ……………. the Earth’s natural
resources, we will cause serious damage to the environment.
3. Most energy resources currently in use are non-renewable. They are also called ………… resources.
4. Changes to water systems may increase the frequency and severity of……………floods.
5. The Tibetan plateau is at the stage of ecological ……………. due to extensive mineral extraction,
deforestation and unscientific construction of highways and railways.
6. They………... an urgent review of the existing control system.
7. Various human activities threaten to disrupt the balance and…………. the world’s ecosystems.
8. We can ……………. our energy problems by learning how the world really works.
9. Technical progress remains the effective ……………… to the ecological threats such as global
warming and pollution.
10. Increasing ………………… is one of the most critical goals in business.
11. Nuclear power plants can ………………a huge amount of power from a single unit.
IV. Use the diagram, sentences and schematic diagram presenting different stages
of electrical energy transmission to describe the transfer of electrical energy from
generating power plants to electrical substations located near demand centers.
A power plant produces electrical energy of medium
(20.000 V) or low (1.000) voltage.
A step-up substation elevates electrical power produced at a
power generation plant to high voltage (up to 400 kV).

University of Mohamed–Seddik Ben Yahia –Jijel
English/ Electrical Engineering / undergraduate (2nd year) Homework
3
Power
plant
Step-up
substation
High voltage
over-Head
lines
Step-down
substation
Medium/
Low
voltage
transformer
Users
Gene rating station
Transmission lines
765,500,345,230 Kv
Step-up
substation
Step-up
substation
Transformer
Subtransmission
customer
Transmission Custmer
138 or 230 Kv
Transfer of electrical energy from generating power plants to electrical substations
Electrical power is transmitted across long distances by high-tension
power lines to reduce the energy losses.
A step-down substation converts the high voltage back down medium voltage
Most of the users are supplied with electrical power of low voltage, but bigger
consumers can be directly supplied with the electrical power of medium
voltage.