G.— ENGINEERING. 173 



advantage to the power station unless the gaseous fuel could be purchased 

 in the necessary quantity at 1.02(?. per therm delivered to the power 

 station, which is equivalent to 5.1ci!. per 1,000 cubic feet of gas, having a 

 calorific value of 500 B.Th.U. per cubic foot. 



Nor does it appear that coke obtained from ordinary gasworks 

 practice can be commercially applied on a large scale to capital power 

 stations. There would, of course, be an advantage to the gas industry 

 if a regular and stable market for their principal by-product were thus 

 procured. In 1924 the principal gasworks of the country produced 

 14.2 cwt. (gross) of coke per ton of coal consumed — -before deducting the 

 amount of coke used for water-gas and for the carbonising plant^the net 

 amount per ton of coal being generally about 10.3 cwt. of coke. The 

 receipts from the sale of coke represented (in the principal gas under- 

 takings) some 19 per cent, of the total income of those undertakings, the 

 average price received having been 27s. 2d. per ton, which, was a higher 

 price than that of the coal used by electricity undertakings at equivalent 

 thermal values. There is, it must be remembered, a wider scope in the 

 classes of coal which can be purchased by electricity undertakings than is 

 the case with gasworks. The fact that in 1924 the average price paid by 

 electricity works for coal was 20s. per ton, and the average price paid by 

 gas undertakings which only produce coal-gas was upwards of 27s. per 

 ton, cannot be ignored, though the latter was of course of a higher thermal 

 quality, containing more volatiles and probably a less ash content. Gas- 

 works coke has a higher ash content and is less easily ignited than coal, 

 and so far has had only an exceedingly limited outlet as power-station fuel 

 in this country, the amount, in fact, being about 1 per cent, of the total 

 coke and breeze available for disposal by the gas industry, and being less 

 than 1| per cent, of the raw coal consumed in the generation of electricity 

 in public-utility stations. It lies with the gas industry to show whether 

 they can supply heat to future large power stations in the large volumes 

 necessary in modern practice, at rates which would be no greater than 

 the equivalent cost of raw coal, and in forms which will be as efficient in 

 application to boilers of large evaporative capacity. If they can do so, 

 then assuredly electricity undertakings should in the national interest give 

 the fullest consideration to such a proposal. 



In the case of low-temperature carbonisation it is obvious that more 

 coal must be consumed for any given heat requirements at a power station. 

 Various technical problems still remain to be solved, and reliable com- 

 mercial data both as to capital and operating costs still remain to be 

 established. The application to a definite purpose, such as steam-raising 

 in a base-load power station, would, of course, minimise any commercial 

 uncertainty, for there would be a definite purchaser of the heat products, 

 while the other marketable products would be limited to the crude fuel oils, 

 for which a sale could probably always be found. 



As Dr. C. H. Lander and Mr. R. T. McKay have pointed out, the peld 

 of coke (with a calorific value of about 12,500 B.Th.U. per lb.) per ton 

 of coal from straight low-temperature carbonisation processes averages 

 14 cwt., and ' therefore the value of the liquid and gaseous products must 

 be sufficient to yield a profit after paying the entire costs of retorting and 

 the costs of about 6 cwt. of the raw coal treated.' 



