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Natural sciences

Grade 8

Energy: electricity, heat and light

Module 2

Present energy sources

  • At present, most of our energy is derived from fossil sources (coal, oil, natural gas with secondary products e.g. liquid petroleum) and nuclear sources. Fossil sources are not renewable and are becoming fewer. Utilising them also causes pollution. Although we may find it difficult to imagine a world without electricity, this energy source is not available in many parts of South Africa and the African continent.
  • In South Africa, energy is provided in different forms, the most important being electricity and liquid fuels (refined from crude oil and coal), coal and biomass (firewood).

The main sources of energy for generating electricity in South Africa are:

burning of coal;

hydroelectricity;

nuclear power.

Coal-burning and power stations

Activity:

To understand and evaluate coal burning as a a source of energy

[lo 2.3, lo 2.4]

At present, coal is the most generally used source of energy, to produce electricity, as South Africa has vast coal reserves. ESKOM coal power stations produce roughly 90% of the country's electricity. We have 18 of these large power stations.

Assignment 1:

Visit the Eskom website to find more information about this type of power generation.

What you mainly need is information on the basic operation of a typical power station.

What does the acronym ESKOM stand for?

To whom is the electricity supplied?

Assignment 2:

Complete the following table to represent the power-generating process by placing the different steps of this process in the correct order.

Turbine turns the rotors of the generator.

Coal is burnt.

Steam drives the turbines.

Electricity is carried away through copper wires.

Coal is ground finely.

Water in pipes is heated to provide steam.

The rotor is an electromagnet that generates electricity.

Coal is mined and transported.

1. ___________________________________________________
2. ___________________________________________________
3. ___________________________________________________
4. ___________________________________________________
5. ___________________________________________________
6. ___________________________________________________
7. ___________________________________________________
8. ___________________________________________________

Assignment 3:

Answer the following questions, making use of the information you have gained concerning the process.

1. What eventually happens to the steam that drives the turbines?

2. How much water is needed to operate this system for a day?

3. Name one place in South Africa where you can see high cooling towers.

4. Name any other waste that is formed during the generation of electricity.

5. Is burning coal for the generation of electricity regarded as “clean” with regard to nature?

Assessment of the steps that are followed in the process of generating electricity:

Were you able to place the steps in the correct order and answer the questions correctly?

[LO 2.3; LO 2.4]

Assessment

LO 2: Constructing Science Knowledge:

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

This is evident when the learner:

  • categorises information;
  • interprets information;

2.4 applies knowledge.

Memorandum

PRESENT ENERGY SOURCES

  • In South Africa the main sources of energy used to generate electricity are:
  • Burning of coal
  • Hydroelectricity
  • Nuclear power

COAL-BURNING AND POWER STATIONS

Assignment 1

  • At present, this is the most generally used source of energy, and therefore of electricity, as South Africa is blessed with vast coal reserves. The ESKOM coal power stations produce roughly 90% of the country's electricity. We have 18 of these large power stations.

ESKOM — ELECTRICITY SUPPLY COMMISSION

  • This organisation provides 95% of South Africa and more than half of Africa with electricity.

In brief, a coal-firing power station operates as follows:

Assignment 2

Coal is mined and transported
Coal is ground
Coal is burned
Water in pipes is heated to provide steam
Steam drives the turbines
Turbines turn the rotor of the generator
The rotor is an electromagnet that generates electricity
Electricity is carried away by means of copper wires

Assignment 3:

The steam that turns the turbines has to escape somewhere - It has to be condensed through cooling, and this requires water!

Each power station requires approximately 150 million litres of water per day. Most of this is lost through evaporation!

Typical cooling towers can be seen along the N2 just outside Cape Town and elsewhere in South Africa.

Waste that is formed during the process comprises harmful gases like sulphur dioxide, carbon dioxide, and nitrogen dioxide – these can bind with moisture in the air and cause acid rain.

Burning coal to generate electricity cannot be seen as a "clean" method and is harmful to nature because of the resultant air pollution, acid rain and particles of ash pumped into the air.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Natural sciences grade 8. OpenStax CNX. Sep 12, 2009 Download for free at http://cnx.org/content/col11050/1.1
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