4
This article was downloaded by: [Monash University Library] On: 05 October 2014, At: 03:55 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Transactions of the Royal Society of South Africa Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ttrs20 How best to meet South Africa's future energy requirements Christopher Molteno a a Bishops Diocesan College , Cape Town E-mail: Published online: 22 Mar 2010. To cite this article: Christopher Molteno (2008) How best to meet South Africa's future energy requirements, Transactions of the Royal Society of South Africa, 63:2, 189-191, DOI: 10.1080/00359190809519225 To link to this article: http://dx.doi.org/10.1080/00359190809519225 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions

How best to meet South Africa's future energy requirements

Embed Size (px)

Citation preview

Page 1: How best to meet South Africa's future energy requirements

This article was downloaded by: [Monash University Library]On: 05 October 2014, At: 03:55Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

Transactions of the Royal Society of South AfricaPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/ttrs20

How best to meet South Africa's future energyrequirementsChristopher Molteno aa Bishops Diocesan College , Cape Town E-mail:Published online: 22 Mar 2010.

To cite this article: Christopher Molteno (2008) How best to meet South Africa's future energy requirements, Transactionsof the Royal Society of South Africa, 63:2, 189-191, DOI: 10.1080/00359190809519225

To link to this article: http://dx.doi.org/10.1080/00359190809519225

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose ofthe Content. Any opinions and views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be reliedupon and should be independently verified with primary sources of information. Taylor and Francis shallnot be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and otherliabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to orarising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Page 2: How best to meet South Africa's future energy requirements

Royal Society national science essay competition 2007 & 2008 189

cal method (i.e. teaching the development of mathematicswithin an historical, social and cultural context) provides morehuman interest than a purely abstract approach and is likely tokeep all kinds of students interested, not just the extremelymathematically minded. Garcia (2007) claims that “When westrip the cultural flesh off of the living, growing body of knowl-edge and present only a dangling lifeless skeleton, we shouldnot be surprised when young minds feel uninterested. Whenwe plunge right into abstract concepts without starting fromconcrete examples that give rise to these abstractions, shouldwe be disheartened that the students have learned little morethan memorising how to manipulate symbols without under-standing what they are doing? Why is it that the mention of“word problems” elicits groans and moans from so manyclasses if not because of this? To bring maths to life we need tofollow the course of history, letting students make the discov-eries ancient Egyptians or Mesopotamians did. There is noreason history must be separated from maths and science. Andthere is no reason that learning maths has to occur only inside aclassroom.”

While Garcia’s line of reasoning is tempting, I personallywould argue against it. The Mathematic Discipline shouldremain untainted by the socio-politics of humanity and standstoically as the clear light of pure reason manifesting in thebeauty of the intellect. Maths as taught in schools should focuson the importance of clinical exactitude and deduction, devel-oping students into a different frame of thinking, rather thantracing an imperfect humanity’s trials and errors. Maths issomething that hovers above imperfection in its abstract purity,mixing maths up with the humanities adulterates this purityand somewhat undermines the above discussed axiomaticsystem, since chronologically a theorem may have been provenhundreds of years after its existence was stumbled upon. Eventhough the ancient civilisations had made use of such a theoryas Pythagoras’ Theorem, its proof is based on axioms only crys-tallised much later. Now if the sequence is taught in itshistorical order, you have effectively disrupted maths as aparadigm of deductive reasoning.

Furthermore, the mode of teaching that Garcia hints at,although intriguing, seems to embrace maths as ideally ana posteriori discipline, i.e., mathematical knowledge originatesfrom observation of a particular experience or aberrationwhich is then dissected by inquiring minds, until certain truthsare discovered. This, as we have discussed at length above, isnot the essence of maths, maths is deductive and thereforea priori – we are not working back, we are working forward.This is what we have to communicate to students. Bycharading the exploits of humanity stumbling backwards tofind mathematical truths, we would be giving the wrongmessage of what maths wants to achieve and how it opensstudents to modes of thinking not explored in other disciplines,even in applied maths or science. The fact that humanity couldnot necessarily first find all mathematical proofs throughdeductive a priori reasoning is really post-facto, ideally it wouldhave been as we can now arrange it: logically axiom-based.

In conclusion, a mathematical education should see as one ofits prime aims on a school level, to inculcate a deductive modeof thinking within young minds, developing their strength oflogical reasoning. Thus educators should constantly be demon-strating maths as an axiomatic system and enforcing theirclass’s conception of this by always linking current work withprevious foundations while reaching soundly for the next stepin logic. To communicate all the above and facilitate the intel-lectual growth of the students, teachers must be excited about

their subject and fully aware of its significance and beauty, thusimbuing their students with a love and curiosity for their fieldwhich precipitates the kind of growth we look for in theupcoming generation.

ReferencesEUCLID, 2007. The Elements. Online: http://en.wikipedia.org/wiki/

Euclid%27s_Elements (accessed 12 May 2007).GARCIA, D.R 2007. Online: http://www.mathforum.com/social/articles/

garcia.html (accessed 28 May 2007).LEWIS, R.H. 2007. Online: http://www.fordham.edu.html (accessed 2

May 2007).

How best to meet South Africa’sfuture energy requirements

Christopher MoltenoBishops Diocesan College, Cape Towne-mail: [email protected]

SOUTH AFRICA’S POWER CRISIS IS ONE OF THE MAIN ISSUES ON A

national level, while the main international issue is globalwarming. The reason that our lack of energy is such a key issueis that it fuels our entire economy and permits the standard ofliving that we are used to. Recently the Electricity SupplyCommission (ESKOM) stopped being able to supply a reliableflow of power and the country has been told that drasticchanges will have to be made before it is restored. The otherrelevant issue is global warming which is exacerbated throughthe production of power from coal (our main source of power).As we need to find new ways of increasing our power supply Ibelieve that the timing could not possibly be better for intro-ducing a cleaner and more sustainable system of creatingpower. This essay will present our choices and short-list theones appropriate for South Africa.

Currently, South Africa (and most of the world) obtains mostof its electricity from coal and all its everyday fuels from oil.Though these are still relatively cheap, easy to obtain andplentiful, we are running out of these fossil fuels, and whilewe continue to use them we are doing huge harm to theatmosphere by adding thousands of tons of extra CO2. In fact,South Africa has double the CO2 emissions per GDP of manyother countries. Our other problem is that we export a lot of ourcoal, and we obtain a far higher price for it than we normallyare given by ESKOM.

The other main contributor to our electricity grid is nuclearpower (nuclear fission). The power is created in this process bysplitting a uranium atom which then creates heat and splitsmore uranium atoms and forms a chain-reaction. This processcauses a vast amount of heat which is used to create steam toturn a turbine to create electricity. This process is highly effec-tive and clean. The highly controversial issue of the danger ofnuclear power is almost ridiculous as the average person has achance five times higher of being killed by lightning than bynuclear power (1 in 30 million) and staff in a coal mine are fivetimes more likely to be killed at their jobs than staff at a nuclearpower station (5 in 100 000) (Driscoll, 1985: 43) It has to be said,however, that if there was a melt-down or some other nucleardisaster, radiation would spread over a huge area and causeterrible damage. There is still a large supply of uranium fromthe earth and it is easy to transport as you do not need as muchas one does for fossil fuels because 1 kg of uranium can produce

Dow

nloa

ded

by [

Mon

ash

Uni

vers

ity L

ibra

ry]

at 0

3:55

05

Oct

ober

201

4

Page 3: How best to meet South Africa's future energy requirements

two million times as much heat as 1 kg of coal (Palmer, 1992: 33).Although spent uranium is hard to dispose of as it still is

potentially dangerous, the vast majority (99.5%), can be reusedfor creating more energy (Driscoll, 1985: 31). Because of its effi-ciency, cleanliness and reusability, I believe that nuclear poweris a very good way of converting energy in South Africa.

A very well known and internationally popular energyconverter is a wind turbine. New designs can create vastamounts of electricity and clusters of them, in appropriateareas, can power whole towns. They are clean, do not requiremuch maintenance and are efficient, but they will only runwhen the wind is above a certain velocity and below another.The wind turbines are extremely expensive to build (from750 000 to about 36 million rands) and once they are built theystill cause problems by being an eye-sore and by – it is alleged –killing birds. The other issue that has to be taken into accountwhen building them is the wind turbulence created by otherwindmills as they shed eddies off their bodies. If the resonantvibration of the second tower has the same time period as theeddy shedding from the first, it will create a bigger and biggermovement of the second tower until the second tower fallsover. Famous examples include the Tacoma Narrows Bridgeand the cooling towers of power station in England. Becauseof the turbines’ wind requirements, the success of a turbinedepends almost entirely on its placing. There are a few poten-tial places in South Africa. One option is to place them offshoreto the South in the roaring forties. However this would mostprobably turn out to be too expensive and impractical as thebad weather could destroy the turbines. Owing to thesefactors, while wind turbines are highly suitable for SouthAfrica, we could not have many of them and wind energycould not be a source that we could rely on.

Tidal energy conversion has been extremely successful insome countries that have appropriate conditions like England.A large bay with a small mouth is a topographical requirement.Relying on a change in water level to turn a turbine, requires adiscrepancy of about 10 m, where as Langebaan (one of ourmost appropriate lagoons) has only a 1 m change in height. Theuse of tidal energy is clean (even if it is a eye-sore), requireslow maintenance (though expensive at the start) and createsenergy constantly. But owing to the absence of appropriateconditions it is impractical for us.

Hydroelectric power has always been the best form ofrenewable energy because in addition to being “clean”, itcreates power constantly and can also be stored. Even so, it

requires perfect terrain and a very large river. It also destroysthe environment it covers, often displaces people and due tosilt building up, frequently has a limited lifespan. While impor-tant, the main factor precluding South African use of hydro-power is that we have nowhere suitable for it. We have theadvantage that Mozambique produces a large surplus from itsinstallation at Cahora Bassa on the Zambezi River to which wehave access.

Wave energy has recently gained a lot of publicity in SouthAfrica because of our suitability for it. Waves in Cape Townhave an average height of 5.5 m (wave energy comes fromwave height2), produce between 30–70 kW/m and have a timeperiod of 9–16 seconds. We have an extensive coastline andwave energy converters convert energy cleanly and continu-ously. The only restrictions are that land-use permissions arerequired, as are a generation permit and an EnvironmentalImpact Assessment. There are numerous designs to choosefrom, many of which are very attractive as alternative energycontenders. A few examples follow.

Pelamis: it uses two or more separate floats held together by ajoint which is bent by passing waves and troughs and thusmoves a piston which in turn drives a hydraulic fluid through aturbine. It converts 1% of energy that passes it.

Sea Dog: it uses a float attached to the sea floor through a hy-draulic cylinder. As waves pass, the float goes up and down anddrives the water inside the cylinder through a turbine andcreates electricity. It converts 1% of wave energy that passes it.

SWEC (Stellenbosch Wave Energy Converter) (Figure 1): theSWEC uses pressure increases and decreases as waves andtroughs go over. It makes use of cement compartments underthe water that are full of air. Each compartment has three pipesleading from it. The first two allow for air to go down through aturbine at the far end and back (each pipe allows air in a differ-ent direction). The third is wide and goes up vertically so as toallow pressure changes to build movement and inertia so thatthe water pushes/pulls air through the turbines. The compart-ments are placed in a diagonal pattern so that two rows powerthe same turbine. There is always at least one trough and onewave over compartments (so as to keep flow continuous) andno wave is used by a compartment twice (the wave is weak-ened when it goes over a compartment). The SWEC is ideal forSouth Africa because it converts 30% of wave energy thatpasses it. Because it is under the water it is not unsightly. (D.Retief, Centre for Renewable and Sustainable Energy Studies,University of Stellenbosch, pers. comm. 2008).

190 Transactions of the Royal Society of South Africa Vol. 63(2)

Figure 1. Stellenbosch Wave Energy Converter (SWEC)

Dow

nloa

ded

by [

Mon

ash

Uni

vers

ity L

ibra

ry]

at 0

3:55

05

Oct

ober

201

4

Page 4: How best to meet South Africa's future energy requirements

Royal Society national science essay competition 2007 & 2008 191

Another underwater energy converter uses the energy fromthe movement of currents. In short, there is a huge fan in anocean current which drives a turbine which, in turn, createselectricity. The idea is appealing because this, too, is notunsightly or inhibiting to other developments and also createsa constant supply of electricity. It is, however, very expensiveand the disadvantage is that it cannot be very large because ofthe drag on the end of the blades. A further difficulty is thatSouth Africa does not have strong fast currents and the middlewould not get enough power. A suggestion to overcome thisproblem is the implementation of Flow Enhancement Ducts (acone-shaped structure that would channel the water through asmall fan in the middle at far higher speeds) but as our currentsare not strong enough for this design to be economically viablethey are not yet worth building in South Africa.

A thermocouple is another way of using currents to createelectricity. It employs the different temperatures created bywarm water going south on the ocean surface and cold watergoing north on the bottom (this in the southern Hemisphere),by having a loop of two dissimilar metals (usually bismuth andtin or constantin and copper) with different thermal potential(if a metal has more thermal potential it releases more electronswhen hot) in the two temperatures. The warmer end of themetal with more thermal potential will push electrons onto theother, thus creating a steady flow electricity. But the thermo-couple only creates 1/50 000 of a volt on each loop so it would benecessary to connect many thousands in series to get a decentsupply of energy. Again, there is a problem that makes SouthAfrica unsuitable for this method, and this is the fact that theoceans around the country have an average temperaturedifference of 16 degrees while the thermocouple requires anaverage of 20 degrees in difference to be made economicallyviable (www.CAPGO.com)

Direct solar energy conversion by way of solar panels has,until recently, been very expensive and inefficient. However, anew design of solar panel has boosted the efficiency from lessthan 15% to 30%. This, together with the fact that South Africahas abundant sunlight, means that solar panels are an increas-ingly attractive option for us.

An aspect that must be taken into consideration whenconverting energy from the sun is the many different designsfor laying out light converters. The French have created a greatdeal of energy for one town by covering an amphitheatre-likevalley that faces the sun’s arc with solar panels that are made tofollow it. In the United States they have created a field of solarpanels which were made to follow the sun in its axis. But themost promising design to date, made by the Spanish manyyears ago, has only recently been brought back to be tried inAustralia at a cost of >US$500 million (it will keep 830 000 tonsof CO2 out of the atmosphere). In short, its design is a large areacovered by a massive sheet of glass just above the ground. Inthe middle of the sheet rises a tower with a turbine at thebottom. The glass creates a greenhouse effect that heats the airunderneath which will start a small current up the tower. Oncethe current is moving the temperature difference between theair on the inside and the outside will be so great that it createsconvection current up the tower and through the turbine. Theone planned in Australia will have a tower a kilometer high andair going up at 56 km/h (www.wired.com) The only otherfeature that has been suggested that might be added to thisdesign is to have pipes under the glass filled with water so thatduring the day they warm up and during the night heat the air.In this way, the current would be kept moving at all times.

In conclusion, I think that once fossil fuels have been

exhausted or we require far more energy than we have, andneed to save energy where we can, we will have to rely on acombination of nuclear fission (fusion is not yet economicallyviable), small wind farms where appropriate, wave energy (theS.W.E.C. is our most promising choice at the moment), solarpanels and solar towers.

ReferencesDRISCOLL, V. 1985. Focus on Nuclear Power. Sussex, Wayland Publishers.PALMER, J. 1992. Radiation and Nuclear Energy. London, B.T. Batsford.www.CAPGO.com/resources/temperature/thermocouple (accessed 14

March 2008).www.wired.com/news/technology (accessed 14 March 2008).

How is global warming affectingour daily life in South Africa and

what can we do about it?

Ilana FinnSt. Mary’s School, Durban

e-mail: [email protected]

Global warming is a steadily increasing problem that is affect-ing the daily lives of people all over the world, including SouthAfrica. It has the potential to cause extensive devastation in thefuture if action is not taken to mitigate it.

By simple definition global warming is the gradual rise in theaverage temperature of the earth’s surface, due to the increaseof certain gasses in the atmosphere. In more detail, the earthreceives radiation from the sun which passes through theatmosphere as short-wave light energy. It is then absorbed bythe earth’s surface and re-radiated back into the atmosphere aslong-wave heat energy which warms the air. There are severalgasses in the atmosphere – such as carbon dioxide, methaneand water vapour – that absorb this long-wave heat energy andprevent it from leaving the earth. They form an insulating layeraround the earth, causing the ground and air below to be muchhotter than they would be without the benefit of this layer. Thisis known as the natural greenhouse effect. It is essential to alllife on earth because, without it, the average temperature of theearth would be too cold to sustain any type of life form. How-ever, with the increase in greenhouse gasses being emitted intothe air, the temperature on earth could rise excessively, leadingto an enhanced greenhouse effect which, in effect, is globalwarming.

The burning of fossil fuels, such as coal, is said to be the maincontributor to greenhouse gasses. This is a problem becausewith rising populations the need for electricity increases,meaning the levels of CO2 being emitted into the atmospherealso increase. Although many of the poorer areas in SouthAfrica do not yet have electricity, electricity consumption in ourcountry is increasing steadily as the government continues toelectrify more and more households. At the end of the apart-heid era in 1994, 36% of the country had electricity, while cur-rently electricity is available to more than 70%. Increasedemissions of greenhouse gasses are already having, and willcontinue to have, a growing impact on the natural and eco-nomic systems in South Africa (International Marketing Coun-cil, 2006).

The average temperature in southern Africa has increased by0.6 degrees Celsius within the last century and is predicted toclimb from 1.4 to 5.8 degrees within the next hundred years.

Dow

nloa

ded

by [

Mon

ash

Uni

vers

ity L

ibra

ry]

at 0

3:55

05

Oct

ober

201

4