G.— ENGINEERING. 175 



carbonisation to large power stations, it is clear that developments are 

 taking place which will bring about a substantial reduction in the cost 

 of generating electricity and effect a more scientific utilisation of our 

 natural fuel resources. 



There can be little doubt about the modern tendency to concentrate 

 the points at which electricity can be generated and made available for 

 general distribution and consumption, whether it be for railway traction, 

 power stations taking the place of the individual locomotives ; or in large 

 industrial plants where a public system of generation and distribution of 

 ■electricity takes the place of individual generating plant at the local 

 works ; or in domestic requirements for heating and other purposes in 

 place of the open coal fire. All of these measures assist in preventing a 

 wasteful expenditure of coal. It is clear, therefore, that any system which 

 can recover the greatest amount of the stored energy available in coal 

 should be fully explored, and it is the large power station of 200,000 kw. 

 and upwards that would appear to offer a means of investigating the value 

 of new fuel processes on a practical scale. 



There has been a far too prodigal use of coal in the past and more 

 .scientific methods for its utilisation are urgently wanted. There is all 

 the waste of small coal at the pits to be dealt with, and there is this question 

 of the more perfect utilisation of the coal which is consumed. Having 

 regard to the recommendations of the recent Royal Commission on Coal 

 and to the very real need for national economy in the present and succeed- 

 ing generations, any improved method which will either turn into useful 

 work the highest heat units or obtain the utmost commercial value of the 

 raw coal consumed must be fully and practically explored. 



There seems little doubt we may expect that within a few years elec- 

 tricity will be generated at modern power stations even with direct firing 

 at a figure of 0.3d. or less per unit. This will be transmitted at liigh pressures 

 for such purposes as railway traction, large blocks of industrial power, 

 and supplies in bulk to local undertakers, who in turn will retail it to their 

 consumers. This involves the construction of high-tension transmission 

 lines or cables and the provision of transformers and switchgear. Broadly 

 speaking, transmission costs would add 10 per cent, to the cost of the units 

 sent out from the power stations, assuming a reasonable average load 

 factor. So we can hope to transmit energy in quantity and transform it 

 locally to the required service pressure at a cost of 0.33d. or less per unit 

 sent out when applied at an average load factor of say 33 per cent. This 

 cost of bulk supplies is equivalent to about O.id. per unit transmitted and 

 delivered by means of H.T. mains, and transformed locally to the requisite 

 pressure. 



In Great Britain it will probably not be possible to make use of overhead 

 lines to the same extent as is possible in the U.S.A. and some other countries. 

 The advantage of overhead lines lies in the ability to use the highest 

 pressures and in their smaller cost compared with underground cables. 

 For equal losses the cost of cable transmission of large carrying capacity, 

 and working at the comparatively low pressures of 33,000 and 66,000 volts, 

 is proportionate to the cost of overhead lines working at like pressures as 

 2.5 : 1 and 2 : 1 respectively. 



