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The Story Of Electrical Energy, Pt. 7 Tasmania, our smallest state, is renowned for its extensive hydroelectric power system. While the hydroelectric system has been the subject of controversy in the past, it uses no fuel and emits no greenhouse gases. By BRYAN MAHER Converting the energy of falling water into useful work is an age-old art. The water wheel has been known since about 200BC in the ancient world, where it was used to turn millstones for grinding corn. Water wheels can be up to 80% efficient and they are long lasting. Some are still going after 150 years of use. Early efforts to generate electricity by the energy of water from a high dam commonly used the horizontal shaft impulse water wheel, known as the Pelton. In this type, a high veloc- Inside Liapootah Power Station. This station is unusual because the alternators are mounted above the main floor level. More common practice is to have the alternators and their turbines below the floor. Commissioned in 1960, the three alternators are each rated at 27.9 megawatts. 98 SILICON CHIP ity stream of water impinges upon cup-shaped buckets mounted around the periphery of a large diameter wheel. One of the world's earliest hydroelectric generating stations was built by the Launceston City Council in 1895, almost a century ago. The South Esk River was dammed and a penstock (a large sloping pipe) carried water down to the Duck Reach power station. Originally commissioned with a capacity of 450 kilowatts, the station was progressively enlarged to 2.2MW by 1919. This plant was retired in 1955, after 60 years of continuous service. How the HEC started In 1909, an ambitious scheme to generate electrical power using water from Tasmania's Great Lake was privately floated by the Hydro-Electric Power and Metallurgical Company Ltd. Government concessions prompted an optimistic start in 1910 when a canal was dug from the lake to Penstock Lagoon, the headwaters of the future power station. Access and transport difficulties in this rugged isolated region were formidable, as no road existed to the power station site at Waddamana. Therefore in 1911, a 27km horsedrawn tramway was built to transport materials and machinery. Sawn hardwood was used for the rails which were laid over rough log sleepers. A number of creeks and one river, the Shannon, required the construction of wooden bridges. The tramway operated return trips every second day, with loads varying from 5-10 tonnes, pulled by a team of 15 Clydesdale horses , harnessed single file. Newly arriving workmen were required to walk to the power station site, a 2-day trek from Deloraine. The pay was 8 shillings per day, with a tent and strawfilled sleeping-sack Hydro electricity is the cleanest form of power available to the human race. While it looks quite modern, the power station at Tarraleah was actually commissioned over 50 years ago, in 1938. It uses six Pelton water turbines, each driving a 15 megawatt alternator. provided free. All excavation work was-done by the time-honoured pick, bar and shovel method. By 1914, costs had escalated and the private company appealed to the government for financial assistance. The Tasmanian Hydroelectric Department was then set up by the state to take over and complete the project which was finally commissioned in May 1916. By the following August, almost 2000 electricity consumers in Hobart were supplied from Waddamana. So successful was the venture that the station was expanded progressively. The level of Great Lake was raised 12.5 metres by the building of the Miena Dam. Seven extra machines were installed, raising the station's output to 49 megawatts, a considerable figure in those days. Between 1939 and 1949, an additional station, Waddamana B, was constructed next to the old plant. This new station contained four 12MW alternators, also driven by Peltonwheel turbines. In 1988, the old Waddamana A power station was made into a museum as a Bicentennial project. Hydro philosophy In comparison to fossil fuel burn- ing power stations, hydroelectric installations have many advantages: (1) The source of energy is free and wholly renewable, depending only on regular rain and snowfall. (2) Although hydroelectric schemes involve the considerable loss of trees when they are built, once they are operating they cause no pollution, emit no carbon dioxide nor other gases and therefore do not further contribute to the Earth's greenhouse effect. This factor alone strongly favours hydroelectric power generation. (3) Low shaft speeds (100-500 rpm) are usually used. Therefore, hydroelectric power stations are comparatively quiet. (4) The low shaft speeds are conducive to long machinery life. Many plants run successfully for 50 years and more. (5) Though in the past hydroelectric schemes were more costly than coal burning power stations, today this is no longer true. (6) Dams associated with hydroelectric schemes can be indispensable in river flood control. As well as saving lives and farm livestock, this gives big benefits in avoiding damage to property and crops. (10) Hydroelectric turboalternators can be started from rest, brought up to speed and synchronised on line in just a few minutes. Thus, hydroelectric schemes cope excellently with varying electrical loads over a 24-hour day. In this respect, hydroelectric machines are far superior to steam turboalternators which take many hours to come up to full power after cold start. Energy and efficiency The dammed water flows downhill via penstock pipes to the water turbine. Thus, the potential energy of water at a height becomes the kinetic energy of high velocity falling water (see Table 1). To give the greatest possible power output, designers aim for the greatest possible head. If the penstocks can drop vertically from a dam to an underground power station, water friction losses are minimised. Where terrain dictates penstocks running long distances down a mountain slope, some energy will be lost in pipe friction (turbulence). This fact places an economic limit on the distance from a dam down to JANUARY 1991 99 Inside Tungatinah Power Station, commissioned in 1955. This station uses five alternators rated at 25MW each and driven by Francis turbines. All that is visible here are the housings for the exciters and sliprings. the power station. The energy advantage of a high head may therefore be partly cancelled out by turbulent losses in long pipes. So instead of building one dam high up in a river's headwaters and one power station far down below, we often see a multiple installation. Many dams are constructed along the same river. At each dam, the water is piped through a power station to be returned to the river below the dam. Thus, the same water passes through many power stations, generating electrical energy in each. Hydroeiectric systems may then consist of six or more small or medium size power stations spread along 100 SILICON CHIP the length of a river. This contrasts with the coal-fired steam power station philosophy where economies of scale tend to concentrate one or two very large installations close to mines. The Derwent scheme An excellent example of the repeated use of the same water flowing downstream is the River Derwent system. In the upper headwaters, the Tarraleah power station was built in 1934/38, during the Great Depression. At that time, 25% of Tasmanians were unemployed. In the inaccessible mountainous regions of the upper Derwent, the first task was the building of an access road known as the "14 mile". For five months through winter and spring, labourers toiled, cutting a track from the old West Coast Road to the power station site. Tarraleah power development obtains its water from the upper Derwent catchment area. A weir was built to raise the natural level of Lake St Clair by 2.4m, which greatly increased the water storage capacity. The water released flowed down the Derwent, then via a canal and penstocks to Tarraleah power station. February 1938 saw the first three 15MW machines in operation at Tarraleah. Work then continued slowly on the installation of a further three units. All use Pelton type turbines which are shaft-coupled to low speed alternators. By 1951, the 6th generator was in operation, bringing the station capacity to 90 megawatts. To increase the water storage supplying Tarraleah, the Clark Dam was built in 1951. A second system of flumes and tunnels added in 1955 feeds water from the dam to the Tarraleah headstock at Mossy Marsh. The 67-metre high Clark dam, closing Butlers Gorge on the Derwent (downstream from Lake St Clair) forms man-made Lake King William which is some 42km 2 in area. These two lakes together can store 740 million cubic metres of water. Included in the Clark Dam structure is the small Butlers Gorge power station, where one Francis-type turbine drives a 12.2MW alternator. A very unusual situation evolved when the 125MW Tungatinah hydroelectric power station was built in 1953. This station is driven by water from a chain of six lakes fed from the Pine Tier Dam on the Nive River. As the Nive is itself a tributary of the Derwent, Tungatinah power station was built adjacent to Tarraleah. The exit tailraces from both stations enter the Nive river almost at the same point, though each station is driven by water from different catchments. From its confluence with the Nive, the Derwent continues down the mountain, the water flowing through a further six plants: Liapootah, Wayatinah, Catagunya, Repulse, Cluny and Meadowbank power stations. None of these plants on the Derwent system is very large, with capacities ranging from 12.2MW to ELECTRONICS WORLD JANUARY SPECIALS USED 'AA' 700mAH NICAD BATTERIES $ 0.50 TEMPERATURE CONTROLLED SOLDERING STATION $135.00 UNIVERSAL NICAD BATTERY CHARGER $ 29.95 Can do 4 at a time (AA, C, D, or 9V Nlcads) 40 CHANNEL AM CB RADIO $ 79.00 SMOKE DETECTOR $ 49.95 PIEZO SIREN WITH BACKUP BATTERY $ 59.95 Ideal for Car Alarms DIGITAL DISPLAY AM/FM STEREO CAR RADIO $ 49.95 PORTASOL GAS SOLDERING IRON $ 35.00 ARLEC SUPER TOOL KIT $ 69.50 LOGIC PROBE $ 35.00 SCANNER FANATICS FREQUENCY REGISTER OF VIC. $ 24.95 PHILIPS INFRARED REMOTE CONTROL $ 35.00 COMMON CATHODE 7-SEGMENT DISPLAY $ 1.00 VIDEO DUBBING KIT $ 15.95 ARLEC 2 SPEED CORDLESS DRILL AND SCREWDRIVER $ 69.95 This photo inside Tasmania's Waddamana A power station gives a graphic view of a Pelton wheel water turbine. Now turned into a museum, the Waddamana A station was the first built by the Hydro-Electric Commission. 125MW each. Nevertheless, the total output of all 10 stations exceeds 500 megawatts - all from the one river and its tributaries! sliprings seen in the photo. Like an iceberg, most of the machinery mass is out of sight below, with only the exciting generators visible. Vertical shafts Types of turbine Most modern medium to large hydroelectric generators use the vertical shaft construction. Tungatinah is an example, with five 25MW machines installed. Each has a Francis type water turbine installed deep in the bowels of the station. Above the turbine, but on the same shaft, is mounted the main alternator; in this case, still below the turbine room floor. Above the floor level are the exciters and main Three types of water turbines are in use: the Pelton, Francis and Kaplan. Which of these is chosen for a power station design depends primarily on the water head height available. A secondary consideration is the variation-of efficiency with load changes. The Pelton wheel, with many buckets mounted around the periphery of a large wheel, is the oldest. Modern Pelton designs apply the water through adjustable flow nozzles and 2-CHANNEL FM WIRELESS INTERCOM $ 89.95 SINGLE CHANNEL UHF TRANSMITTER KIT $ 18.00 SINGLE CHANNEL UHF RECEIVER KIT $ 34.90 VULTURE CAR ALARM KIT $ 39.90 INFRA RED NIGHT VIEWER KIT $239.00 TALKING ELECTRONICS ULTIMA FM BUG KIT $ 12.50 Mail Orders Welcome 30 Lacey St, Croydon VIC, 3136. Telephone: Fax: (03) 723 3860 (03) 723 3094 (03) 725 9443 JANUARY 1991 101 BNC PLUGS AND SOCKETS BNC MALE PLUG 1-9 10 ,99 100.. P10514 S2.50 '2.25 $1.50 ~ · ·· HEATSINK COMPOUND S.¥e • tmall tortune on OteN hHllink. thus " Direct tmpo,1" low proll .. le increasing overall toekets! PCB mounling sotmr tall . All tin plated phosphor bronze or berryffium and dual wipe for reliability. 10 ·~ 1()(). P10550 :- 1-? ULTRASONIC 10·~ 10('1. 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S411 SMART DRIVE ADAPTER IDEIFDC .......... $89 SMART DRIVE ADAPTER IDE 1/0 IFDC .•• $119 p1aye"' etc RIPPER STRIPPER • 3 x Metal Oxide Vartstors (MOV) Remove ugly paper feed edges •MaximumclampingVottage: each MOY: 710 vol1s at 50 amps quicklyandcleanlywllhthis simn.l rttl d t ~=?.:.:.~=~.:~::.95 C21085.~.~.~ ..~.~·······$14.95 Only $24.95 RS232 GENDER CHANGERS • Saves modifying or replacing non-mating RS232 cables • All 25 pins wired straight through Cat· X 15650 Male to Male Cat X 15651 Male to Female Cat X 15652 Female to Female Normally $14 .95 each OnlY$8.95 MOTHERBOARDS XT 10M MINI ••.....•••.••••••.•••• $120 XT31M,_ _ _ _ _ _..,199 I XT 12M STO. SIZE.. ••••••••••• S199 SUNTEC AT12M. ...............$375 80386-25... .!!'~M~.... $2,695 8D386- 33 ••• 1!-!:~l'.'1!L.$2,995 RODIRVING ELECTRONICS SYDNEY: 74 Parramatta Rd Stanmore . 2048 Phone (02) 519 3134 Fax (02) 519 3868 MELBOURNE: 48 ABeckett SI. Phone (03) 663 6151 RS232 MINI TESTER • Male to female connectmns • All pin wired slra,ght through • Dual colour LED Ind1cates ac1tvIIy and direction on 7 Imes • No batteries or power requi red T.D. TransmI1 Data O.S.R. Data Set Ready A.O. Receive Data C D. Carrier Detect R.T.S. Request to Send O.T.A. Data Termmal Ready C .T .$. Clear to Send C at. X15656 Normally $39.95 s NORTHCOTE: 425 H,gh SI Phone (03) 489 8866 CLAYTON: 56 Renver Rd Phone (03) 543 7877 MAIL ORDER & CORRESPONDENCE: P.O. Box 620. CLAYTON 3\68 Order Hotline : 008 33 5757 (Toll free , strictly· orders only) lr,quiries : (03) 543 7877 Telex : AA 151938 Fax: (03) 543 2648 I MELBOURNE DEALERS MICRODOT 177 SPRINGVALE ROAD NUNAWADING. Pll.894 1255 GREENSBOROUGH COMPUTERS 87 GRIMSHAW ST (en, Howard et) Ph: 434 S1SS COPYHOL.D E 7 (YU-H32) • Adjustable arms allows. ea1y positioning • Copy a re■ 91 /2" x 11" • Sliding line guide • Clamp mounting BRISBANE DEALER VRC COMPUTER SERVICE 147 LUTWYCHE RD . LUTWYCHE, 4030 ADELAIDE DEALER M CROTRONCS C21062 ••.....•••. $39.95 305 MORPHETT ST ADELAIDE, 5000 All sales tax exempt orders and wholesa~ inquiries to: RITRONICS WHOLESALE . 56 Renver Road. Clayton Phone: (03) 543 2166 (3 lines) Fax: (03) 543 2648 PRINTER LEAD Suits IBM• PCIXT, compatibles • 25 pin "O" plug (computer end) to C entronlcs 36 pin plug SPECIFICATIONS: . Electrical rating, 240V /1,C, 50Hz, 10A XT' Cover Set C21066 .......•......•... $14.95 AT' Cover Set C21068 .•..•.............$16.95· CENTRONiCS GENDER CHANGERS • Female to Female . • Saves modifying o r replacing non-mating Cenlronics cables • All 36 pins wired straight through . Cal . X15663 Male to Male Cat . X15661 Male-to Female Cat. x15664 Female to Female _Normally $33.95. 4 PORT SERIAL •••.••... .•••• S89 VGA 2561<. ••••••••••••.....••••. S199 VGA 512K....................... $299 SPECIAL. ONLY $32.95 C~1 •Includes pull-out shelf tor ~ 2'~m;~e ~°;;7;~~~r20 4 WAY Cat.X 19125 I $69.95 C21058 (80 column) •High qu.iity ABS plastic and 0 • Two/Four position rotary switch on front panel • Three/Five interface connections on rear panel • Switch comes standard with NATIONAL PANASONIC KXM110 PRINTER RIBBON C22034 ............ :.....$19.95 A working bench tor your Mouse. z • No power required • Speed and code transparent DUST COVERS MAGIC STAGE < RS232 DATA TRANSFER SWITCHES If you have two or lour compatible devices that need to share a third or fifth, then these inexpensive data transfer switches will save you the time and hassle of constantly changing cables and leads around . . C22003 .. $12.95 ....,:.. -. 50 JOUies Protection Level : 350V peak to check on paper supply • Paper can be fed from the cen tre or the rear according to !he design of the p·nnte, • Removci.ble drawer which allows paper to be changed w11hout moving the pnnler • Retrac table reaI basket makes print-out collec tion fa st and convenienl • Suitable for mos! printers ~ ,._, 0 positions . ENCLOSED PRINTER STAND .. . .. ·- ~ f~;~~o~~W~!e Q~ CJ) 0 1 0 ~ nr~=~c~ ~ncir~~~fi - > 0 ~ IJ;J RS232 BREAK OUT BOX CPF CONTINUOUS POWER ALTER SPIKE ARRESTOR THE BUTTON SPIKE PROTECTOR l1~4~A~ II ··--···- .: .. .. • . metres 18 P1 9029.................. $ 14.95 3 • metres P19030 ...•..•• ••.•..••.• $1 9.95 •10metres P19034 $39 95 .•••.•..•.•..••.•• • Errors and om1ss,ons · · excep ted . Prices and specifications sulijectto COPY HOLDER (YU H33) :;,i;.a~\, .. ,,-..,.,,..,.,.,.,.;,...,..,, intem11iona1 BusM>Hs Macn,nes c~~bs~albase "AWe " • ;=°'~.,.;.~ •Copyarea9 ' ,.;"x11.. • Sliding tine guide '-~::z rei,ster&d . $39.95 vJ ~ Q ..... ~ ~ FREE PACK & POST ON ALL ORDERS OVER $25.00 IN JANUARY. EXPIRES MIDNIGHT 31-01-91. · J;"_R_J;'~ PAr'T< lr POCT ON AT f ovn:coc:...n,,-co c,:-,c: llft_I_~ T.A 11i.TT I A.D'-l r.vnn-.r.c ••n·, ... n,..TT'T' ... 1 n1 n1_ UHF HIGH GAIN ANTENNAS antenn existing systems triangu/ powder coated receiving elements ensures excellent UHF reception compared to other UHF antennas of similar size and price. Two models are available: the TVA14 for Band Four and the TVA 15 for Band Five UHF reception. Both models are supplied with back reflectors to prevent ghosting as well as a waterproof entry box designed to accept 75 ohm coaxial cable without the need for addittional baluns. They also have predrilled holes for securing the tilt adjustable metal mounting bracket in either a horizontal or vertical position. Imported and distributed by: ~ ELECTRONICS Available through the following retailers: Bemys. Bridgepoint. Military Road. Mosman. 2088. NSW. (02) 969 1966. Ritronics. 56 Renver Rd. Clayton. Victoria. 3168. (03) 543 2166. CHRISTIAN BLIND MISSIQ~ ·d Re,8totiKf t~~~,, be1K COUPON Please cut and send to : CHRISTIAN BLIND MISSION INTERNATIONAL. P.O. Box 5, 1245 Burke Road. KEW. Vic. 3101 Phone: (03)817 -4566 D e Please send me further information about CBMl's work. As long as it is possible for me, I will help: D monthly D quarterly D annually D to prevent blindness D to restore eyesight D to rehabilitate the blind Enclosed is my gift of$ _ __ _ __ Mr; Mrs . Miss, s,~~t, .. . City, 104 SILICON CHIP Devils Gate Dam in flood. Measuring 84 metres high and 1,34 metres long, this concrete arch dam was built in 1969. Water from the dam feeds a Francis turbine which in turn drives a 60 megawatt alternator. are used with water heads of 200 to 2000 metres. Pelton wheels may be used with vertical or horizontal shafts. The Francis water turbine , used exclusively with vertical shafts, is suitable for water heads from 35 to 550 metres. In this type, the water is admitted via a spiral casing and circulates around the turbine rotor while falling to the tailrace directly below. The water's momentum is thus transferred to the rotor which in turn drives the alternator above. When the electrical load increases, more water is admitted to provide more power. Because of the water's pathway, partly circular and partly downwards, the Francis is called a mixed flow turbine. This appears to be the mostused type worldwide, probably because many dam systems yield head in this range. The Kaplan water turbine is almost identical to a ship's propellor mounted on a vertical shaft. Water is admitted to a chamber above from whence the water falls vertically through the propellor blades, so turning them. This type is used for small heads up to about 60 metres and is preferred in 'run of the river' systems. In these plants, the aim is to maintain the river flow rate. This is often necessary to meet irrigation and city water supply requirements, or additional hydroelectric power stations further downstream. The use of variable pitch blades in the Kaplan turbine allows the power produced to vary according to the electrical load, without changing the water flow rate. In-the Derwent river system, Kaplan turbines are used only in the downstream Repulse, Cluny and Meadow- ---------- ------1·-------- --! l _____J 2 8 ----=-----=--- --==--==-----==--- This cross-sectional diagram shows a "run of river" power station driven by a variable pitch Kaplan turbine. Variable pitch turbines allow the river flow to be maintained at a constant rate. The key to the diagram is as follows: 1 - water turbine; 2 - normal level of water on upstream side; 3 - water turbine pressure oil unit; 4 - alternator; 5 - indoor switchgear; 6 - transmission line to the outdoor step-up substation; step-up transformer; normal level of water on the downstream side. bank power stations. The latter is only 50km upstream from Hobart city which demands a continuous and ample water supply. By contrast, Francis turbines are preferred in the mountains where water heads are generally higher. Also in these power stations, the water flow rate can be adjusted as the electrical load demands, as ample water storage exists downstream. Efficiency Water turbine efficiency varies with the electrical load on the driven alternator. The Francis turbine is the most efficient at full load but shows poor efficiency at low load. Table 1: Power Generated By Hydro Stations The power generated by any hydroelectric scheme is given by: P = DgWHE watts, where: P = electrical power output in watts D = density of water = 1.0t/m3 g = acceleration due to gravity= 9.81 m/s 2 W = water flow rate (in m3/s) H = head; ie, vertical height of dam water above the turbine (in metres) E = efficiency factor to account for energy losses due to: (a) turbulent friction in penstocks and turbine; (b) mechanical bearing friction;(c) electrical losses in generator and transformer. This reduces to: P = 9.81 WHE (kW) Pelton and Kaplan turbines exhibit top efficiency over a wide range, from 0.3 to 1.2 times full load. Fig.1 gives some indication of these comparisons. Underground power stations Tasmania first ventured into underground power station design and construction at Poatina, at the northern end of Great Lake. From this high water storage, over 1000 metres above sea level, a 6km sloping tunnel, a hillside penstock and a 153-metre vertical shaft carries water to the power station built deep within the mountain. The extra cost and work involved in burrowing through solid rock, cutting out a suitable cavern and installing large machinery is formidable. But this cost is offset by the energy gain due to the very great head of water and the reduced friction losses through using a short vertical penstock. Because of its high water head of over 800 metres, Poatina uses vertical shaft Pelton water turbines. Six turboalternators, each of 50MW capacity, were installed and commissioned in 1964. The turbine room, cut out of the solid mountain interior, is 91 metres long, 14 metres wide and 26 metres JANUARY1991 105 This view inside Tungatinah Power Station while an alternator undergoes a major overhaul shows the very large diameter of these machines, relative to their power output of 25 megawatts. Water turbine powered alternators are always very much larger than steam powered alternators because they run at much lower speeds. Steam turbines run at 3000 rpm (to generate 50Hz AC) whereas water turbines run at between 100 and 500 rpm. This means that their alternators must have many poles and therefore a very large diameter. high. Above run the heavy-lift cranes used during installation and maintenance. The outflow water from the turbines runs via a tunnel and an open cut channel to Brumbys Creek, thence into the South Esk River, eventually to be reused by Trevallyn power station 60km downstream. Poatina, contributing 300MW to the state grid system, is remotely controlled from Palmerston, 6km distant. Access to the power station is by a vertical lift shaft and a 1km long roadway tunnel. 100 To increase the available water storage for Poatina, the water level of Great Lake was 90 raised in 1981 by increasing the height of Miena dam by 6 metres. This rockfill dam, 28 metres high and well over a l 80 kilometre ' long, contains c..,> nearly half a million cubic ;:;i::i metres of solid material. The ~ 70 present capacity of Great Lake is over 3000 million cubic metres of water. 60 106 SILICON CHIP 50 h/1/ --" ,,,,. 'I r/ ~ ~ "I Glacial lakes :r'he Tyndall Ranges, 800m above sea level, enclose many glacial lakes at approximately 500 metres elevation. The Anthony River drains this area before plunging down through a gorge to 240 metres elevation. This is one of the state's wettest areas, with rainfall averaging 3800mm annually. The catchment will be held in Lake Anthony by a 47-metre high concrete-faced rockfill dam. A pressure tunnel 5.5 metres in diameter and 7.5 kilometres long will carry the water down to the new Anthony underground power station. With a water head of 267 metres, a single 86MW Francis turbine and alternator will come on line in 1991. Next month we will look at the Gordon River system, where Tasmania's largest hydroelectric machines were installed underground. I Mersey Forth system Between 1968 and 1973 , the Hydro Electric Commission brought into operation a system of seven dams and seven power stations which were all driven by the one river and its tributaries. This construction stretches from Lakes Rowallan and Mackenzie through Lakes Cethana and Barrington and Devil's Gate Dam. Finally, the water flows via Lake Paloona to the sea through Mersey Forth, near Ulverstone on Bass Strait. These seven power stations contribute a total of 308 megawatts to the state grid. Presently, construction is progressing on the Anthony River development in the Tyndall Ranges in north west Tasmania. A system of five small dams and one power station will generate 83MW. White Spur dam, rising 43 metres, will contain 140,000 cubic metres of rockfill with concrete facing. The smallest will be Henty, a 24-metre high concrete mass gravity dam. 0 Acknowledgements 20 40 60 80 100 120 LOAD(%) Fig.I: this graph shows the efficiencies of the three type of water turbine, Pelton, Francis and Kaplan. Special thanks to the Public Relations Office of the Tasmanian Hydro-Electric Commission, to Liz Emson and ABB journal. SC