Thailand - Technical report on the Chainat Hydro-Electric Project

g~~~~~~~~~1ES K- .L(Y1>k!:JJ -~~~~~~~~L 913 F~22 |This report is restricted to use within the Bank INTERNATIONAL BANK FOR RECONSTRUCTION AND DEVELOPMEiNT TECHNICAL REPORT ON THE CHAINAT HYDRO-ELECTRIC PROJECT IN THAILAND June 30, 1950 Loan Department  TECHNICAL REPORT ON THE CHAINATHYRO-ELECTRIC PROJECT IN THAILAND c of the Project The Chainat Hydro-Electric Project has to be considered in conjunc- tion wviith the Chao Phya River Irrigation Project. The irrigation scheme pro- vides for the construction of a barrage at Chainat to maintain a river water surface level for gravity irrigation. The barrage is an essential part of the irrigation project. The difference of water levels up and downstream of the barrage creates a head vrhich can, within certain limits, be used for igen- erating hydro-electric power. Because of limitations in the water supply not regulated by a reservoir, the project required a complete analysis of river discharges. Elr. W7. N. McLeod, the Irrigation Consultant, was assigned to re- port on the technical features of the hydro-electric development at Chainat. The following report is based on his findings and recommendations. The Project It should be made clear from the outset that the Chainat Barrage is first and foremost an irrigation work. It follovrs from this that only the normal flow of the river passing below the barrage can be used for power generation and no use can be made of the water stored behind the barrage. Stored water can be used only if the level of the stored water can be lowered within cer- tain limits. Since, however, the whole object of cornstructing the Chainab Barrage is to maintain the water level, that object would be defeated if the level were lowered in order to supplement the discharge available for power generation. It might be suggested that stored water of which use could be made might be obtained oy raising the upstream wrater level above that required for irrigation purposes. A barrage under these conditions and the storage reservoir would be very costly and this scheme could not be economically jus- tified, The Chainat Barrage, as part of an irrigation project, is designed primarily for irrigation and not for hydro-electric development and the amount of powrer which can be generated has to be determined within the limits imposed. Power Available - Under the proposed development it must be ascertained whether it is possible to produce continuous pow:rer throughout the year or for identical periods of the year which could be described as seasonal powers. Hydrographs of the river at Chainat are available for a period of )44 years from 1905 to 1948. An examination of these records show that if the barrage had been in exis- tence during these years, the generation of power during 32 of them would have been impossible for periods varying from h to 84 days, because, owing to the high level of the water below the barrage, there would have been an insuffi- cient head to drive the turbines. This would have been true even if the water  0 levrel above the barrage had been raised to the maximum duiring the high flow period in order to create as much head as possible. It is also found that in 29 years, for periods varying from 2 to h3 days, the discharge below the barrage which is the balance of the river discharge after meeting the demand of the irrigation canals, would have been insufficient to generate any powfrer. There were, in fact, onlyr 4 years out of the 44 in which there wrould have been no interruption of the power supply, had the barrage and hydro-electric instal- lation existed. It follows from this that no continuous power could be gen- erated at Chairnat. It is also the case that no reliable seasonal power could be delivered because according to the records, there are only 4 months in the year, February, Fiarch, April and May, in wvhich interraptions would not occur. No manufacturing process could be satisfied with power for so short a time, particularly when, during the period, the river discharge and conse- quently the povwer supply, would be at a minimum. The conclusion is that hydro power generated at Chainat could only be used, when available, to save fuel consumed in established thermal-electric power plants and could make no con- tribution to carrying any part of the load on a continuous basis. The only saving that a thermal powier plant could effect by taking hydro power would be on fuel, because that is practically the only part of the cost of operating the thermal plant that would be eliminated by using hydro powfer. it follows that the charge per unit of hydro powrer delivered to the thermal plant must not exceed the cost of fuel per unit of thermal power. *- Installed CapaciytZ - The hydrographs showr that it is reasonable to take the miniiium dis- charge as 100 cubic meters per second. It may, on occasion, fall below this figure but not often enough or for long enough periods to make it necessary to work on a lower figure. To fix the discharge wlhich will pass belovw the barrage and therefore be available for powrer generation, it is necessary to de- duct 50 cumecs to be consumed above the barrage -for dry season irrigation of soya beans and for the maintenance of navigation in the canals. With 50 cunecs passing the barrage, the head will be a minimum of 9 mters and the power that can be developed, on the basis of 85% overall efficiency, will be 3,750 kv. It would, howrever, be a mistake to fix the output of the individual generating units as low as this. On the basis of the average minimum flowr and head, the amount of kilowr.att-hours that could be annually obtained from a larger generator is considerably greater than the amount that could be gener- ated writh a 3,750 kvw machine. Calculations showN that a 4,000 kw unit would produce annually 30,000,000 kuh, and a 4,750 kw unit would produce 3L, 000,000 kwh per year. The producti-n gain is thus 4,000,000 lkrrh per year for one unit and a similar calculation shows the gain to be 10,000,000 kwh for an installation of four units of 4,750 kw each. If substantially smaller units were adopted, it would be necessary nri order to take full advantage of the potential povwer produiction of the site to install more machines at a greater cost. There is, therefore, a good case for fixing the capacity of each gen- erating unit at 4,750 kv. 0 To determine the number of generating units to be installed, the annual production of 1, 2, 3 and It units has been examined; beyond this number, the gain in kwh produced is no more justified by the cost of installation. wring  -3- to variation in the consumerst demand a certain proportion of the generatied energy cannot be sold; furthermore, allowance must be made for local consump- tion at the hydro plant and for possible breakdowns and interruption in power supply. The theoretical output has thus beeii conservatively reduced by 2`150 and by a further 8% to allow for losses in the transmission lines and sub- stations. Applying these percentages, the number of kvh which could be an- nually generated and sold are indicated in the following: Number of 4,750 kVw Annual theoretic- Annual opera- Annual supply to generating units al output kwh tive output kwvh consumers - kwh 1 3h,Q000,000 25,500,000 23,500,00O 2 67,000,000 50,250,000 46,ooo,ooo 3 l00,000,000 75,0001000 69,000,o00 h 130,000,000 97,500,000 89,5oo,o00 The choice of the number of units on the basis of the above figures vrill be made in accordance with the markets available for electric power. MIarket for Power - The only market contemplated by the Thais is the cement and steel works at Tha Luang located some 100 km from Chainat. According to iiformation, the existing power installation at the plant has a capacity of 1,500 kvr with !500 km stand-by capacity, and an additional generating plant with a capacity of 1,500 kw is under order. The total installed capacity will therefore be 3,000 kw with 500 km stand-by. Details an the company?s manufacturing program and future development plans are not available. Based therefore on a 3,000 kw demand and on a load factor of 70% due to the continuous processes, the corm- pany's thermal station would produce 18,500,000 kwh per year. Not all thLs out- put could be covered by hydro power generated at Chainat; as indicated, no hydro povwer could be supplied during 25 days each year, alnd therefore a propor- tionate amount of the above demand wvould have to be met with thermal power. The works at Tha Luang would thus be a potential customer for hydro power in the amount of 17,000,000 kwh annually. It has been shown that one 14,750 kv unit could deliver 23,500,000 kwh per year to consumers. Thir is much in excess of the requirements at Tha Luang, so that the installation of one such unit would involve an estimated loss oX a saleable 6,500,000 kvrh. This, however, is only a fraction of the loss entailed by not taking advantage of the full potential production at Chainat. Referring to the fig4res given in the table above, it will be seen that by installing four 4,750 kmT units, 89,500,000 kIh could be delivered to consumers if a market could be found. This market capable of consuming all the output of the hydro power plant is available at Bangkok, wrhich is at a little * over 200 km from Chainat via Tha Luang. The electric power supply position at Bangkok is deplorable. Both existing thermal power plants were damaged during the war and only partially  repaired. The useable installed capacity of the two power stations of about 16,000 ktT is totally insufficient for the requirement for light and power. All theequipment is outdated and inefficient. VJith newT capacity supposedly un- der order and the repair of existing equipment, the available capacity may rise to 30,000 ku in a year or two. It is estimated thiat the present demand is 25,oo0 lkw and that it will quickly rise to and exceed 30,000 kw. On the basis of this demand and of a load factor of 50% considered to be reasonable, the yearly consumption at Bangkok amounts to 131,000,000 kvih. Applying the factor of 0.93 to this figure to allow for the fact that the hydro power plant wvould shut doimn on the average for 25 days each year, the hydro powzer that could be sold in Bangkok if it were available would be 122,000,000 kvh. This exceeds now the output of the hydro plant by 32,000,000 kwvh and it is certain that the excess of the Bangkok demand will be even greater by the time the hydro plant is completed. There is thus an assured market for hydro power generated at Chainiat even if there were no demanid at Tha Luang at all. C o s t s Cost of the Project - The estimated costs of a one unit and a four unit installationf or units of an individual capacity of 4,750 lrw, including transmission lines, are 0F3 given in Tables 1 and 2, The local currency costs and foreign currency re- quirements are itemized for both alternatives. An overall 10%0 provision for contingencies has been included and ,300,000 added for consulting engineer's fees. No provision has been made for interest during construction. The es- timates in round figures are as follows: Item Total in Foreign Cur- Local Currency renc, Cost One 4,750 ki unit 48 million bahts . 2.2 million Four h,750 kw units 96 million bahts $ 4.6 i Annual Charges - The annual charges are worked out on the followiing assumptions: a) Operation and maintenance at 1% of capital cost; b) Depreciation at 2% for structures and at 4% for all plant items; c) Interest at 5% and amortization in 30 years requir- ing an annual charge of 6.5% on the capital coSt.  -5- B a h t s Item 1 Unit Plant 4 Unit Plant Capital cost 485,oo,0o0 96,000,000 Operations and mainltenance 48o,000 960,000 Depreciation 1,530,000 3,270,000 Interest and amnortization 3,120,000 6,20,000 Total for annual charges 5,130,000 lo 470,000 Say - 5,100,000 balits 10,500,000 bahts Economic Positi onl - The first alternative is the installation of one unit of 4,750 knw to meet a demand of 3,000 kvI installed at Tha Luang. As previously estimated, the supply from Chainat would be limited to 17 million kwh per year. It has been explained that to justify the hydro installation, it must be able to deliver power at a cost per kwh not exceeding the cost of fuel per kwh at the thermal station, EnqLuiries elicited the statemttent that the cost of fuel-oil per kwh at Tha Luang wras 0.22 bahts. Thus, the annual cost of fuel for 17 million kwh would be 3,800,000 bahts and this is all the company at Tha Luang could pay f or hydro power. As the annual charge for this alternative has been computed above at 5,100,000 bahts, it is clear that this solution rmust be rejected on the basis of its financial return. The only tangible benefit would be a saving on the importation of fuel oil for the thermal plant, worth 3.8 million b