Is There a Future For Town Gas Fuel ?
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Whilst at Present Gas Fuel Cannot Compete With Oil Fuel There Are Possibilities, Says an Authority, if Certain Conditions Could be Met
THE subject chosen by Mr. A. H. Mills, M.Inst.Gas.E., A.M.Inst.Mech.E. (Portsmouth and Gosport Gas Co.), for his paper which he read, on Wednesday last, at the Industrial Transport Association's Congress at Norwich, concerns the use of town gas as an alternative fuel for petrol engines.
Just as the stationary steam engine was the forerunner of the units as applied to locomotives, road vehicles and to ships. so the stationary gas engine led to the development of the internal-combustion engine as we know it. Whereas the steam-driven vehicle or ship was, and is, easily and economically capable of carrying its fuel in comparatively solid form as a small proportion of its gross load, gas. under normal pressure, is much too voluminous for use on transport vehicles.
Comparison of Calorific Values.
By way of comparing calorific values by volume, Mr. Mills says that 1 cwt. of coal, which occupies about 2 cubic ft., or 10 gallons of petrol occupying about cubic ft., are approximately equal to the calorific value of 3,000 cubic ft. of town gas. As the author points out, however, the efficie.ney from " coal to work " is probably something less than half that from " gas to work," but even so, the gas volume still remains unmanageable.
The obvious answer lies in compressing the gas, and one might say, on first thoughts, that 3,000 cubic ft. compressed to 2 cubic ft. would be 1,500 lb. per sq, in, pressure, that is, by applying the law that the pressure of gas varies inversely as its volume, conveniently overlooking the fact that the pressure referred to is absolute pressure. The actual pressure will be rather more than 22,000 lb. per sq. in., which, as Mr. Mills says, is quite another matter.
After dealing with the early attempts to store a reasonable supply of gas, and with the fact that, even using crude and improvized systems, the value of using gas was proved, the author deals with the modern type of" bottle " in whirls high-tensile alloy steels are employed. The production of these steels, in . conjunction with intensive experimental and research work, has resulted in the manufacture of bottles which may be charged up to 5,000 lb. per sq. in.
in this connection, he relates some interesting experiments which have been carried out in order to test their safety. Such a bottle, after being charged to a pressure of 3,000 lb. per sq. in., was dropped from a height of 30 ft. on to a concrete block, the velocity at impact being 44 ft. per second, which is equivalent to 30 mph.; no appreciable change was noticed in the bottle and the fittings remained intact.
After dealing with some of the advantages which follow the use of town gas as a fuel, Mr. Mills mentions a specific case, in which a fleet of five vehicles, of _from 1-ton to 3-ton capacity, were run an town gas with results which were in every way completely satisfactory. The records showed that about 260 cubic ft. of gas, at ordinary pressure, equivalent to 11 therms, is equal to 1 gallon of motor spirit. It is pointed out that this is a general comparison.
Equivalent to Motor Spirit at 3d. Per Gallon.
Dealing with compression costs, these vary according to the size and continuity of operation of the compressing plant, although a round inclusive figure would seem to be about is. per 100 cubic ft., or a figure which is equivalent to motor spirit at 3d. per gallon.
The author ventures the information that two of the reasons why gas, as a motor fuel, has not so far been developed are (1) the firm establishment of motor spirit, (2) the advent of the oil engine suitable for road transport.
In respect of the latter, it would appear, says Mr. Mills, that compressed gas cannot compete economically with oil as a fuel for road-transport services under present conditions. There are, however, two or three possibilities which might change the situation to the advantage of using compressed gas. These are (1) an allowance in respect of the weight of the gas bottles when assessing licence duties, (2) the development of a satisfactory method of enriching coal or coke-oven gas, (3) the development of a special engine to use compressed gas to greater advantage.
Towards the end of his paper, Mr. Mills touches o'n the possibilities of the utilization of producer gas, and, in this regard, he says that if steam could be generated in a unit comparable in weight with a gas producer there seems no reason why steam should not return to favour.