USE OF COAL

Evening Post, Volume CX, Issue 11, 12 July 1930, Page 13

USE OF COAL

HYDEO-BLECTEIC

PLANTS

NATIONAL ECONOMICS

(To the Editor.) Sir,—Your correspondent, "Coal User, who subscribed the article under the above heading in your issue of 7th July, will expect to hear what I have to say m reply to his criticism o£ my previous article. I trust that you, Sir, will pass for publication my following comments upon the most interesting statements which "Coal User" has made. In the first place, the norn de plume "Coal User" is a somewhat ill-chosen guise under which to deprecate so very decided]y the use of coal. "Coal User" would prefer to let the coal fields of New Zealand remain untouched lest his children's children shall not have so much coal buried, down in the bowels of the earth as. there W to be in his day. He s.^ emphatically, let Australia export to *c ' /e«^ 500,000 tons of coal per annum -(the: ngme given), it saves that .amount of New Zealand coal for posterity. What does it matter if 750 000 tons of New Zealand, brown coal could replace that importation itom Australia and at the same time give employment to 1000 or 1500 men of the Dominion. Unemployment is, not a serious, factor in the mind' Of. -"Goal User. According to statistics published by the Government Mines Department, the fields of bituminous brown'coal and lignite already proved -containing 663,000 tons of fuel, the half of New Zealand's coal has doubtless not yet been surveyed at ■all, in fact, the same authority■ states that the probable quantity, of .coa is 1,631 000 000. "Coal User" maintains that about 3,000,----000 tons'of coal arc required annually, me known deposits will .thus provide Coa User's" children's children ■ with luel foi at least 200 years, and the probable coal in the safekeeping of the islands will last for over 500 years, unless the population oi New Zealand is to increase at an appalling pace.' Will it be such a gross injustice to generations that are yet to be, if the coal miners of to-day are SJyeiv employment^ the winning of those 700,000 tons per annum to replace imported Australian coal, and an additional 500,000 tons of coal per annum with which to generate that 400,----000,000 units of electricity supplied ironi. the hydro-electric-plants—a total employment of, say, 2000 men (and food for their families) in the winning of coal to generate electric power at perhaps halt the cost 'of hydro-electric generation and to replace the foreign coal, Can we not rightly infer from these coal facts and the sequence of Nature that m, say. 500 years' time coal will be all usedup and Nature not having altered her way appreciably in that, to her, short time, rain (i.e., water) will still fall for service at hydro-electric stations. Now, let us look at the facts of hydroelectric and steam plants. -England, France (except in the mountain districts), Germany, Russia, Italy (the same reservation aa for France) are all more or less flat countries, great areas of which are devoid of water- power. Steam generation has leapt forward in those countries. Naturally so. The stoppages due to coal strikes have been but few and oi short duration—even the great general strike of all trades in England failed to disrupt the electric supply for a single day from any one of the main stations. Pulverised coal firing of boilers has been raised to such a state of automatic perfeotion that a nucleus crew of college boys under the station supervisors and engineers can keep a super power plant at work so long as the reserve of coal at the station lasts. The shutting down of the "huge power station at Morwell" due to a miners' strike is a circumstance which can; easily take place in Australia, whereby the whole local community suffers, is not one which New Zealand labour is likely ever to folOV. " ' ■ ' ::■..'.'■' New Zealand labour ' is' far more far-

sighted and balanced to deviate from its:, strongest support-^generalipHblic opinion—' aa to the justice.of its\demands.,,We..c»n look 'to American practice for-a typical example of steam power.' plant versus, hydro-electrio generation. The -writer has no data for the last two years, but sure it is that pulverised coal has materially swelled tho figures for steam plants since 1927, while no increase in hydro-electric generation has taken place. The relationship of water power to coal, and oil plus natural gas, was then 7 per cent., (i 3 per cent., 3Q per cent., and although of recent application, pulverised coal firing then represented 22/ per cent, of the total output of coal-fired stations. From 1919 to 1927 hydro-electric generation had increased only from 5 per cent, to 7 per cent. In the same years to give an unbiased comparison coal-fired stations had decreased from 75 per cent, to 63 per cent., and had lost ground to what? —not hydro-electxic generation by more than 2 per cent.—but to oil and gas-firing, which has increased from 20 per cent, in 1919 to 30 per cent, in 1927. That these facts are beginning to dawn upon the Public. Works Department of the Dominion is apparent from the announcement' that an emergency coal-fired State-owned station is foreshadowed in the locality of the Huntly coal mines; furthermore, it is known to the writer that the P.W.D. have recently studied the literature of the day concerning the muchdiscussed pulverised coal-firing of powerhouse boilers. The giant super power stations throughout the coal-bearinjr world created during the past eight years have practically all been equipped with pulverised coal-fired boilers of immense size and high evaporative power. Whereas the rated capacity of stoke-fireil water-tube boilers used to be no higher than 4% to 5%1b of steam per hour per square foot of heating surface, tho boiler ratings of to-day are as high as 10 to 13 lb of steam.' To this increase of boiler duty is also added the evaporation capacity of the water-tube linings of the furnaces designed for. pulverised coal firing. The total evaporation per square foot of combined heating surface is thus approaching 201b of water, compared with the iVj to 5%1b .a few years back.

"Coal User" rightly contends that IVi 1b of (raw) brown coal containing perhaps 15 per cent, free moisture and of 10,000 B.Th.U. value per lb would be insufficient under New Zealand conditions to generate 1 k.w, hr. Average bituminous New Zealand coal, however, has a value of 13,500 B.Th.U. per lb, and less than 5 per cent, free moisture. For pulverised coal firing free' moisture must be as a rule reduced to 5 per c^nt., and allowing for the quantity of water in brown coal to be dried out before firing, the tonnage figure given by the writer can be increased to 55,000 tons or even 60,000 tons without detracting from the value of the main arguments. It has been shown that oil and gas firing in America has made appreciable progress. The scientific distillation of the volatile constituents of coal, brown or bituminous, enables the valuable oils to ibe recovered, the residual fuel to be considerably raised .in calorific value, and the surplus gas rendered available for any purpose. It is not too far a stretch of imagination to picture the commercial treatment of both bituminous and brown coal whereby the B.Th.U. value of the residual fuel will be raised considerably, and the tar- oils and gas, used to advantage for the raising of steam as in America. The disposal of surplus gas and low grade" oils is qfteu the disquieting lealure of coal distillation projects, and such a combination of coal treatment and power generation plants is the' natural line along which science will dictate an advance in the better utilisation of fuel. That 400 lives should have been lost in New Zealand coal mines i» to be deplored (the period is omitted by "Coal User ), but it is a well known fact that transport workers suffer far greater casualties than coal miners in England and other

countries—and so possibly in New Zealand. If this is also the case in New Zealand "Coal User" should advocate the closing down of all methods of transport. Again "Coal User" denounces steam turbines because they "fly to pieces," and yet the great units at power houses up to 100,000 k.w. in a single steam turbine, and prime movers for battleships, cruisers, and ocean' liners, : are nowadays of that flimsy design which may fly_- to pieces at any moment. Transmission lines are analogous for either system of power generation, and no credit for reduction in cost can be claimed for either. The cost of coal at the power house by "Coal User" is one which should not be brought to the notice of the coal owners who are now supplying coal to the Auckland Powei'Board. The old contract price for coal was about 7s per ton—the present price since the failure of Arapuni is 10s per ton—uud "Coal User" suggests a reasoiiablc figure of £1 per ton as a "low price.' There is no denying the fact that the cost of raw coal must be an item iv steam power generation which is absent in hydro-electric power, but is it right to capitalise the cost of coal, be that what it may, at 5 per cent, or any other rate of interest, and to conclude that this capital value can be accorded tb'*^a hydroelectric station of similar plant capacity? Apart from reserves of coal the "live" capital expended upon , coal ..is purely a revenue item. It is taken care of in th,e overall costs of operation, and is covered from day to day by working capital, not plant capital, and it returns a relatively •high rate of interest in the shape of the trading profit made daily upon the power generated and sold. . Thus an extra £1,000,000 (to quote from the letter under reply) of "dead" capital spent on hydroelectric plant, that is the capitalised.value of the cost of coal at : £1 per ton, at 5 per cent, interest, quite apart from maintenance and depreciation charges, would absorb £50,000 per annum of the revenue of the station. On the other hand the expenditure of £50,000 on coal, per annum (no depreciation or maintenance applies in this case) at 5 per cent, interest would absorb but £2500 of the.revenue realised from steam power plant operations. The question is this—would a power board prefer to have a standing charge against profits of £50,000 or £2500? The number of units of electricity sold annually is the same in each case, and therein lies the rub of standing charges against hydro-electric systems of power supply, when coal is available, abundant, and inexpensive. On the question . of' station" efficiencies "Coal User" really has the pull for a hydro-electric plant efficiency, but he does not say that the-'figure he mentions has been established at Arapuni; neither.docs die realise that present, day. steam power engineering has recorded station overall thermal efficiencies of nearly 30 per cent., and turbine efficiencies well over 80 per cent. . --■ ' ' The final contention the writer will venture to make is in regard to the meritorious statement by "Coal User-' to the effect that in the construction of hydro-electric plants "the extra cost is spent in New Zealand on New Zealand cement, sand, and gravel^ New Zealand timber, etc.," and later "the capital cost of labour is very much greater for a hydro-electric scheme than for a steam power system.' Now is it of greater advantage to New Zealand taxpayers to labour, and to mami-. facturers to spend stupendous sums upon the temporary production and. utilisation of cement, gravel, sand, timber, and upon construction labour for the building of a monument? of costly power—a work to be completed, say, in three years—than to spend one-third or one-half of tho capital cost upon an admittedly more economical steam power plant for which the labour of the Dominion will not only be required in the making, but in far greater numbers thereafter year in and year out in the mining of coal and for subsidiary industries. : ..-■:■ ,

The writer has nothing .to say against hydro-electric plants in their right sphere —in Switzerland, the Austrian and Italian Tyrols, in Savoie, Sweden, and Norway, or elsewhere when coal is absent, but in New Zealand they are decidedly out of place in the scheme of national cconril.nics— I am, etc., ■ : ' ' . LEONARD'HARVEY.- '■■