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ALTERNATIVE FUELS?
By Capt. J. B. Walton, M.I.A.E., Chief Engineer, S.P.D., Ltd.
DURING the past decade immense strides have been made in the development of prime movers, and it might be said that no great advance will be possible in the future without a radical change in the unit itself. On the other hand, little or no progress has been made in the development of fuels. It can safely be assumed that out of 1,500,000,000 gallons of petrol imported into this country annually at least 1,200,000,000 gallons are wasted in the form of heat, noise and smell. In other words, the effective use at the road wheels of any vehicle represents only about 20 per cent, of the potential energy available in the fuel for which we pay.
The importation and marketing of this enormous quantity of fuel are governed by immense corporations with large sums of capital invested, amongst which the British Government is by no means the smallest participant. It is to be expected that from these interests a jealous regard will be paid to any alternative to their product. It must be borne in mind, however, that these organizations have built up over the years a distribution scheme and service against which it would be difficult to cavil.
They are marketing a fuel at a price which, tax and distribution costs included, is by no means excessive, and any alternative, if it is to succeed, must at least approach in all aspects the conditions observed by these big combines. Therefore, many years would be necessary.before the full development of alternatives to rival the liquid fuels could be achieved.
Possibilities of Gas Producers I will confine my remarks to fuels for the 500,000 commercial vehicles which are operating in Britain to-day. Let us take first the gas producer, which was prominent to the public eye and failed so dismally. We should require, in days when it is extremely difficult to obtain, approximately 125,000 tons of steel merely to make the plants if, at once, every vehicle had to operate on producer gas.
To fabricate these plants we should require many thousands of men when they are urgently needed for other work, and to satisfy the demand would take many months—in fact, years We should also require annually, at a conservative estimate, at least 3,500,000 tons of special anthracite to operate these plants, although to-day the total annual output of anthracite is only 6,000,000 tons.
If we assume an overall drop in efficiency in the engine of only 15 per cent., the effect on those 500,000 vehicles would be immeasurable in -terms of work performed. One can enumerate difficulties, such as distribution and classification of fuel, and the necessity of skilled drivers, reduction in operative time, etc., until they appear enormous. Moreover, anthracite for this work has already risen from £3 per ton to something like £6, and, as we are advised that most of the anthracite is needed for special purposes, it seems possible that the cost will rise still further, and, in units of work done, rapidly approach the cost of operating o'N petrol. Therefore, it is obvious that development of this form of fuel is out of the question.
The next possible source of alternative fuel would appear to be compressed coal gas, regardless of the fact that, at the moment, supplies of compressed coal gas— as far as we are concerned—are non-existent. It is hardly likely that fewer than 7 to 10 cylinders of gas would be required per vehicle. Simple arithmetic provides a figure of 5,000,000 cylinders for Britain's commercial vehicles.
Cylinder Production Difficulties There is at present only one company in the country that is able to produce these cylinders, and that concern is equipped for manufacturing only a limited number. In any case, the whole of.the company's output is fully committed in other directions. The cylinders are made to a rigorous Home Office specification—the test figure alone calls for a pressure of 4,500 lb. per sq. in.—and are subject to a Lloycl's inspection. Further, they are made of a nickel-chromium molybdenum steel, which is in limited supply and requires elaborate heat treatthent before being suitable to carry the working stresses.
I ,cannot imagine where these cylinders can come from, even to equip 10,000 vehicles, and, in addition to this difficulty, a complicated plant is required to compress the gas up to some 5,000 lb. per sq. in.
Coupled with the compression equipment, an elaborate de-benzolizing plant is needed and to equip a fleet of, say, 50 vehicles, de-benzolizing plant and other apparatus would involve a capital outlay of something like £12,000.
I would not dispute that an adapted engine can be made to function satisfactorily on town gas under a high-pressure system. It is significant that to produce the amount of gas for compression which would be required to run all the vehicles in the country, it would be necessary to carbonize not less than 15,000,000 tons of coal annually. The maximum carbonization capacity of the gas-works to meet the ordinary demands of the country is only 20,000,000 tons, and it would be impossible to extend the output by 75 per cent.
There are further alternatives in the shape of methane obtained from sewage gas and other sources. Again, the collection, storage and liquefying of these gases are complicated and expensive processes, and when all that is available has been collected we are advised by authority that some 300,000 gallons would be forthcoming—whence it is not specifically stated. The apparatus required to adapt an engine to run on this gas is conveniently ignored, and, in any case, the small quantity obtainable makes methane much more of an experiment than a practical expedient.
Other' .suitable liquefied gases are cited, including propane, butane and calor. Most of these are byproducts of coal distillation or coal hydrogenation, and as the total available output is scarcely meeting the demands in other directions, there is little or no hope in the use of these as a fuel, nor is there much hope of any worthwhile increase in quantity. .
With these we seem to have exhausted most of oui possible alternatives to petrol We can, of course, revert to steam, but as there are few steam vehicles in the country, and as they are definitely limited in the work which they cart perform or upon which it is economical to use them, I feel that they can be of little help for some time Special Design Needed I think it is safe to assume that, running on producer gas, the maximum power output of a petrol engine cannot be approached within 20 per cent. With a large engine designed to rug on producer gas the case can be different, but that is not an immediate possibility, neither are special chassis and engines available, or likely to be There is some small hope in the conversion or adaptation of an oil engine to run on producer gas, because in an oil engine the swept volume is much in excess of that Of a petrol engine of equal power It is easier to reduce the compression of an oil engine than to raise it on a petrol engine, and with attention to detail it would, I think, be possible to adapt an oiler to function, as far as power output is concerned, with reasonable satisfaction.
In considering the modification of a vehicle to operate on producer gas, it is essential that the work upon which it is proposed to use the vehicle be carefully laid out in relation to the fuel. The vehicle which is being used for taking, say, 10 tons across the Pennines and is mostly on full throttle, will not do this job, except at a great increase in time and cost.
The location and availability of storage for fuel supplies must also be ascertained, and where the accommodation of quantities of fuel is contemplated at one's own premises, the extent to which insurance premiums will be affected must also be given serious thought.
Smaller Power Drop
Reverting to compressed gas, we find a more favourable condition of affairs in relation to the capacity of the engine to run on it, and to the apparatus involved. With a reasonable-quality gas of 450-500 B.T.U.s per cubic ft., it is passible to operate with a maximum power drop of 10 per cent., and with this it might be said that transport can operate satisfactorily.
We might take it that, with a gas of this quality, an amount between 250 and 260 cubic ft. equals a gallon of petrol. 'Therefore, we need storage capacity on the vehicle for a quantity of gas equal to 10 gallons of petrol, bearing in mind that this must suffice for a round journey. To store this quantity of gas would require approximately seven high-pressure cylinders weighing approximately 150 lb, each and costing about £11 each. A two-stage reduction valve would also be required on the engine and there would be certain necessary adaptations to the carburetter, which would cost a further £25.
It would be safe, therefore, to assume that it would cost £125 to equip a vehicle for operation on cordpressed gas and add to its weight 10 cwt., but with a little planning no interference with the cubic capacity for the load should be experienced. It is necessary to feed into these high-pressure cylinders gas compressed to some 5,000 lb. per sq. in. It would not be a practical proposition
to feed direct from a compressor into the vehicle because of the time involved.
To supply the storage cylinders at the bases, of which . a larger number would be required at high prices, it is necessary to have a high-pressure compressor of probably at least five stages, driven by an electric motor or other prime mover. Before the gas can be fed to this compressor, a de-benzolizing plant is necessary—unless the gas has been treated at the gasworks. This is because of the polymerization of the benzole molecules under pressure. .
If, therefore, we take a typical installation for, say, 50 Vehicles, we require 350 cylinders, 50 sets of reduction valves, storage capacity for 125,000 cubic ft. of gas, let us say .16 cylinders each 14 ft. long by 1 ft. 9 ins, in diameter (this storage capacity is assuming that the compression plant will work 20 hours per day), a compression plant with a motor of approximately 50 h.p, to drive it, a de-benzolizing plant, and skilled attention to operate this apparatus. This procedure must be followed whether the equipment is installed at one's own garage, at a public garage, or at the local gasworks.
Two Large Drawbacks It will be readily visualized that fcir a public-service garage to feed perhaps 1,000 vehicles, the amount of plant necessary to provide compressed gas at all times would need a huge capital outlay. I also feel sure that serious insurance question,s, would be raised on any large-scale application of the principle.
Such other alternatives as liquefied butane and methane are virtually unobtainable in this country, and the plant required to manufacture them is so elaborate and costly that little prospect lies in these fuels. Large quantities are being used in Germany to-day as being preferable to petrol. Had more thought been given by Britain to the questionof alternative fuels in the past, it is possible that the position might now have been different.
There is a variety of satisfactory alternative fuels for the oil engine. Many of my readers are probably familiar with the research which I carried out a few years ago with vegetable oils for this type of unit. I suggested as long ago as nine years that soya bean, which could be readily grown in this country, would provide a perfectly satisfactory fuel, but'as no steps have been taken to develop the idea and as all vegetable oils are in the same position as petrol, we cannot at this juncture regard vegetable oils as available alternatives.
Use of Creosote Some slight relief can be given to operators of oilers by the use of creosote, waste lubricating oil and any other combustible in liquid form which can be introduced into the tank. There are no technical difficulties in their use other than, perhaps, slight trouble with cold starting, but this can be readily overcome by injections of paraffin. I have refrained from saying anYthing about the electric vehicle as an alternative to petrol, because electricity cannot, strictly speaking, be considered as an alternative fuel. In any case, I feel that the arguments in favour of electric vehicles hold good just as much in peace-time as in war-time.
The basic fact which cannot be ignored is that during the past decade this country has been " brought up" entirely on petrol, and actually there is no alternative to liquid fuel. The whole road transport system of the aountry has been designed around petrol. Nothing other than laboratory work has been done to cultivate home fuel resources, and until some Governmental or other m&asures are taken to effect a compromise with the foreign petrol interests, it does not seem possible to
take our national resources a step forward in relation to the transport industry of the country—neither is it wise to change horses in mid-stream.
If one considers the question of hydrogenation of coal, one finds that elaborate experiments have been conducted at Billingham under the aegis of Imperial Chemical Industries, Ltd. The results of these largescale experiments have come up to expectations and 5i1OW that by hydrogenating 146,000 tons of coal it is possible to obtain 100,000 tons of petrol. We are told that the cost of plant to produce this quantity is between £3,000,000 and £4,000,000, and that the estimated cost would be approximately 7d. per gallon.
We are also told, however, by various authorities, that it can never be economic to hydrogenate'our own coal supplies. In other words, it is preferable to have 50,000 men out of work and coal mines redundant, and pay gold to extra-Imperial interests. The matter is one for an economist, however, and I am merely an engineer.
I feel that it is possible to erect a plant to produce tha liquid fuels which we require in sufficient quantity to ease our present burden and to leave us with a valuable addition to our national equipment, and a permanent method of absorbing the miner's efforts and our ample potential coal supplies I feel that this is a true alternative to imported petrol and one which could have full effect, but the coal problem must first be solved The development of more economic prime movers rests with the demand of operators and the ability of the technicians, but, in any case, is a long-range policy. The development of indigenous vegetable fuels from our overseas possessions is again a long-term policy, but to those who are far-sighted enough to undertake this work, the reward should be great.
[h is agreed that the liquefaction of methane, and its use in this form, are attended by some difficulties, but we scarcely think that the author does full justice to the use of methane in gas form. The story of Croydon Corporation's achievement in the use of sewage gas, as told in our issue dated March 7, would go to show that where supplies are available, it at once forms at least one possible solution of the alternative fuel problem.—ED.)