244 



NATURE 



[October 21, 1920 



Possible New Sources of Power Alcohol. 



By C. SiMMONDS. 



Two reports have recently been issued dealing 

 with various aspects of the fuel question. 

 The first 1 is devoted larj^^ely to a consideration of 

 the supplies of alcohol which might be made avail- 

 able for use as a motor fuel ; the second ^ includes 

 a note upon the production of alcohol from coke- 

 oven gas, with a memorandum describing the pro- 

 cess now being developed experimentally lor the 

 purpose. In the present article it is proposed 

 briefly to survey the position as regards alcohol, 

 leaving aside the question of alternative motor 

 fuels. 



As noted in the first of the two reports, the 

 enormous and rapidly increasing consumption of 

 liquid fuels is tending to exceed production, so 

 that it is very important to supplement those now- 

 employed by developing the use of new ones in 

 every possible way. In the United Kingdom the 

 quantity of petrol received during 1914 was about 

 120 million gallons; the imports in 1919 had risen 

 to 200 million gallons, and the estimate for the 

 present year is 250 million gallons. 



It is now accepted that alcohol, either alone 

 or mixed with other liquids, can be used to replace 

 petrol in internal-combustion engines, the most 

 suitable fuel being probably a mixture of alcohol 

 with benzol, or with benzol and ether. But to 

 get alcohol we must first obtain the raw materials. 

 These are, in the main, starch- or sugar-containing 

 plants. So far as this country is concerned, grain 

 (barley), potatoes, and mangolds would appear to 

 be some of the most suitable crops : the last has 

 not hitherto been used for the purpose to any 

 large extent. Reckoning, for present purposes, a 

 gallon of alcohol of 95 per cent, strength as equi- 

 valent to a gallon of petrol, how much of these 

 raw materials should we require to supply the 

 250 million gallons which represent our annual 

 consumption of petrol? 



We should want more than 4 million tons of 

 barley, or i2i million tons of potatoes, or 25 

 million tons of mangolds. Roughly, the total 

 annual production of potatoes in the United King- 

 dom is only one-half, and of the other two 

 materials barely one-third, of these quantities. 

 The barley we produce is already largely used in 

 the making of malt ; the potatoes and mangolds 

 are foodstuffs. Since this country is very far from 

 being self-supporting in the matter of food, no 

 considerable proportion of these crops could be 

 diverted to increase the production of alcohol. 

 They command a much higher price as foodstuffs 

 than could be paid for them as sources of "power " 

 alcohol. 



Our own case is fairly typical of the position 

 in general. Foodstuffs, whether produced at 

 home or abroad, will probably for some time yet 



1 "Fuel for Motor Transport." An Interim Report by the Fuel Research 

 Board, Department of Scientific and Industrial Research. (1920.) 



2 " Fuel Economy." Third Report of the British Association Committee. 

 (1910.) 



NO. 2660, VOL. 106] 



be too valuable for use on any large scale as 

 sources of alcohol. Meanwhile, what of possible 

 new sources? 



.As regards synthetic methods of making alcohol, 

 there are only two which, so far, have come near 

 to commercial success. One of these is the manu- 

 facture from calcium carbide, itself produced from 

 coke and limestone. The carbide yields acetylene, 

 which by appropriate chemical treatment is con- 

 verted into acetaldehyde ; and the aldehyde, w-hen 

 mixed with hydrogen and passed over heated 

 nickel as catalyst, is reduced to alcohol. The pro- 

 cess was to have been worked on a large scale in 

 Switzerland, but little has been heard of it lately. 

 It may have been remunerative during the war, 

 but has not developed as much as was expected, 

 and appears now to be hanging fire. In any case, 

 cheap power for making the carbide is essential ; 

 and according to some German calculations it 

 would be more profitable to convert the carbide 

 into cyanamide, and use this as a fertiliser to 

 increase the potato crop for conversion into 

 alcohol. A much better yield would thus be 

 obtained. 



The other synthetic method is based upon the 

 utilisation of a by-product. The gas emitted from 

 coke-ovens consists mainly of hydrogen (50 per 

 cent.) and methane (25 per cent.), with smaller 

 quantities of nitrogen, water vapour, and tarry 

 impurities, and about 2 per cent, of ethylene. 

 After a preliminary purification of the crude gas 

 to eliminate tarry matters, ammonia, naphthalene, 

 and benzene hydrocarbons, the greater part of the 

 ethylene can be absorbed in strong sulphuric acid, 

 forming ethyl hydrogen sulphate, wnich, when 

 diluted with water and distilled, yields alcohol. 

 Experiments have shown the possibility of obtain- 

 ing 1-6 gallons of alcohol per ton of coal carbon- 

 ised, and according to some estimates the cost of 

 manufacture would be about 25. per gallon. 

 Assuming a similar yield from all the coal car- 

 bonised in British coke-ovens (about 15 million 

 tons per annum), the yearly supply of alcohol 

 from this source would be _ about 24 million 

 gallons. The manufacture, however, is at present 

 only in the early stages, and it is too soon to 

 judge what the permanent prospects are. But, 

 even if the suggested yield of 24 million gallons 

 is eventually reached — and this, for various 

 reasons, is unlikely — it would be less than one- 

 tenth of our present petrol consumption. It would 

 be a very acceptable contribution, but insufficient. 

 An increase of 100 million gallons or more should 

 be aimed at. 



Thus, for the moment at least, we are still 

 dependent upon fermentation methods for any con- 

 siderable increase in the supplies of alcohol. We 

 come back, therefore, to the question of ferment- 

 able raw materials. 



Still dealing with the needs and possibilities of 



