ECONOMY IN COAL

Dominion, Volume 11, Issue 116, 2 February 1918, Page 9

ECONOMY IN COAL

WHAT WATER-POWER MEANS BIG SAVINGS IN CANTERBURY

.What the Lako Coleridge installation means'to Canterbury in tlie saving of coal -is explained by Mr. L. Birks, electrical engineer to the Public Works Department, in the "New Zealand Journal of Science and Technology." The annual saving exceed, £100,000. Economy in the use of coal, says Mr, Birks, is of particular importance just now as a meawre of national efficiency, owing to-the demand on man-power for the prosecution, of the" war and for essential'industries. The coal consumption in the most efficient and well-de-signed steam plant in Canterbury—the tramway power station—for the last complete, year of coal-firing was about SBOO tons to generate 5,179,457 units with a normal maximum load of about 1200 kilowatts, or 1600 horse-power— that is, over 5 per horse-power year, working on about a 50 per cent, load factor. The ordinary small commercial steam plant consumes from three to five times lis much coal as this, though." its load factor is low—usually 10'per'cent.' to 20 per cent.—the owner does hot, as a rule, realise how much coal per actual horse-power hour it is using. It is found in practice that the average power actually: used in small, factories is usually from one-half to one-quarter of i what the owner estimates—his estimates being based' on maximum .rather than on 'average power. The average small steam plant ou a 15 to 20 per cent. load factor actually uses 6 to 8 tons of coal per horse-power per annum. And thus the Lake Coleridge plant, replacing such plants and working, up to a 50 or 60 per cent, load factor, saves 15 to 25 tons of coal per. annum per horsepower of its useful output. Good suction-gas plants are ■ more (•ffiqient'when workinjj at or near full load, but at ordinary load factors those that have been replaced by Lake Coleridge power have not appreciably reduced the quantity of fuel saved, per horse-power year of electric output. It. is well within the mark to put down the actual saving that has been_ effected , by Lake Coleridge power, working a 50 J to 60 per cent, factor," at over 10. tons : per horse-power year. The actual out-; put. of-the plant at present from the ] Addington distributing station is 4000 kilowatts—i.e.. 5300 horse-power, or, allowing liberally for losses in distrßur tioii, 4400 horse-power delivered to the consumers. It is thus effecting an actual saving in fuel consumption of over 44,000 tons per annum, probably well over 50,000 tons, worth £75,000 delivered into the coal-bins or £100,000 delivered into the boiler fires. •_ The greater, portion of this saving is represented by the wages.of miners, railway men, seamen, wharf labourers, carters, firemen, and clerical hands, and represents the labour of nearly four hundred men, who are replaced by sixty to eighty •men engaged on operating and maintaining tile Lake Coleridge power plant, distribution, sub.-stations, and reticulation. To some/extent the electric power lias replaced kerosene and petrol instead, of coal; but to ibis extent'the saving lis of. even' greater national importance, in that it has substantially reduced ocean and railway transport, and has reduced our national liability to foreign creditors by probably £10,000 per year. Moreover, hydro-electric power is a step' in the right direction in another important aspect. The hard, exhausting, unskilled, and monotonous labour of mining;, trucking, shipping, shovelling, carting, and firing is replaced by the comparatvely easy, clean, aiid scientific (though probably somewhat monotonous) employment of watching the turbines,and attending the . switchboards, -or.' the-, more interesting outdoor life of, patrolling and maintaining the transmission lines and distribution lines. Instead of working underground, we now work away up amongst the mountains.. Instead of demanding mere physical strength,, the now method of power sitpnlv calls for the highest development of ingenuity, initiative, and skill, even" amongst its routine workers.

The coal will not, of course, be left in the ground. The stimulus of industry will open iup other uses for it. When burned in boiler furnaces the whole of its valuable nitrogenous and coal-tar products are wasted, and of its heat value at most 5 to l(j per cent, can bo converted into power even with the most efficient plant. With new processes, an increasing quantity will first be distilled in gas retorts for tho .recovery of the nitrogen and tar products, and the coke will be employed in electro-chemical and oTectro-thermal nrocesses. in which offiei»noies of 50 to 60 per cert., instead of 5 to 10. per >ont. will be obtained. In such directions as these, economies of the utmost notional importance are already being effected, and will become of increasing importance in tho very near future.