Fractionating Road Transport
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in Terms of Fuel WE have been so long accustomed to the use of petrol as the fuel for road transport purposes, that we have come to think that there is only one fuel to use for that job, and, after the war, that fuel may be denied to us.
Let us, therefore, climb up out of that petrol groove, of which the sides are steep and have been carefully greased so that we should be prevented from climbing them, and just look around in the atmosphere above the groove, to see what else is going on in the world.
What do we see?
. If our vision be sufficiently long, we see that there are at least seven other fuels than petrol doing, in other places, the same job that petrol and oil are doing for us—in a much restricted manner, however.
These fuels are producer gas, town gas, electricity, methane, ethane, propane and butane.
Producer gas is used in Sweden and Russia with raw wood or charcoal as fuel; in Germany, with charcoal and pre-war imported English coal ; in France and Italy, with charcoal; and, in the small way in which this country has adopted it with anthracite and lowtemperature coke.
Town gas has been in use in Germany compressed into cylinders at 3,000 lb. per sq. in., whilst in France and Italy a certain amount of development has been carried on too.
No Progress Until a Year Ago Again, in this country, nothing has been done for 20 years, but at the outbreak of war we restarted where we had left off. Much progress has been made in the past 12 months, but it has been almost limited to the roof bag, as steelalloy cylinders for compressed gas are not available to any practical extent, nor is compressing. or debenzolizing plant, owing to the exigencies of war.
Electricity as energy for transport (so far as the self-contained unit is concerned) has made small headway for many years. So long ago as the 1880's battery electric vehicles commenced to appear on the streets of London, and between 1900 and 1910 electric taxicabs were available in the West End.
The limitation of these vehicles was, and still is weight and small mileage per charge of the battery. Up to the outbreak of war, the number of electric vehicles on the roads was under 5,000, and the annual production had never reached 1,000. In Germany the number on the roads was 22,000. Quite recently, Italy suddenly awakened to the advisability of enforcing battery traction.
Methane has been developed as a fuel for internal-combustion engines for several years. in Germany. It is, hawever, not pure methane, but contains ethane 14 per cent., ethylene 16 per cent., and 6 per cent of other combustible gases. The methane content is 64 per cent. It is manufactured, being a by-product to the treatment of coal for the production of petrol.
The methane of this country does not depend upon the manufacture of any other commodity ; it is a waste product in any case, and it will be available, in circumstances of barrel, imported fuel, either for storage in roof bags, compression in steel cylinders or for use in liquefied form. In this last case the mileage will approximate to that of petrol.
Ethane is a fuel that has been used for aero engines in the U.S.A., but not to any great extent, and not by itself in any other country.
Propane has been in use for some years in the U.S.A. for transport vehicles, stationary power plants and industrial heating purposes. A complete system of storage and transport of this gas in its liquefied form has been developed and has been in operation for a number of years, in the same way as petrol distribution is organized.
Butane has also been developed in the same way as propane in America, and its distribution organized.
In Germany, America and, to a very limited extent in this country. propane and butane have been used as a mixed liquefied gas in equal proportions. In this country it has not been used as a fuel for engines, because there are only such small quantities available. Of these seven fuels, so far as this country is concerned, ethane, propane port of the country with a view to the efficient use of the fuels, and to the advantage of the nation's foreign exchange.
The following figures give a general idea of the mileage possibilities per charge of various fuels:—
Town gas (roof bag), 20-25 miles per charge.
Town gas (cylinder), 1 1-6 equivalent petrol gallons per cylinder.
Electricity (battery), 30-40 miles per charge.
Steam. 50-100 miles per charge. Producer gas, 150-200 miles per charge.
Petrol and oil, 200-250 miles per charge.
Allocating Fuels to Classes In the same way that the fraction-. ating column separates out the different grades of fuel from the crude oil that contains them all, let us get it to separate out the various classes of transport from the totality, and see what kind of separation takes place.
The results of this operation are given in the accompanying "Transport Fractionating Table."
This table merits the following comments: Long-distance transport, both goods and passenger can be suitably carried out by producer gas. Long runs with few stops are the most favourable duty for this fuel. With short runs and frequent stops the temperatures of the producer fire are so variable that gas values vary, fires clinker up and the gas is not properly cleaned. On long runs, owing to less frequent and violent temperature variations, these conditions are much improved.
Further, this type of transport is usually run by large organizations which are in a position to set up and administrate the extra departmen't necessary for the efficient maintenance and cleaning out of producers and scrubbers at the necessary regular intervals.
Urban passenger transport, which., of necessity, passes the same point several times a day, can be dealt with either by town gas, if the single journey be under 20 miles, and the vehicle be suitable for its equipment, or by electricity if it be over 20 but under 40 miles.
Gas and Electric Charging Times Gas recharging takes only 6 to 7 minutes, and exhausted electric batteries can be replaced with fully charged ones in the same time, if suitable equipment be used. Methane is a little farther off, but when available will double the mileage per charge of town gas, owing to the calorific value being double that of town gas.
Municipal cleansing services are of small mileage, but have frequent stops, and are particularly suitable to electric traction, as restarting a vehicle from a standstill is much more efficiently done by electricity, with its high torque at low speeds, than by an internal-combustion engine, with its multiplicity of gear changes to obtain the necessary starting torque. Electric vehicles have already made a place for themselves in this market, for the above reasons.
Gas, water, electricity and other municipal undertakings with transport necessities can suitably be considered as self-contained, because gas, electricity and methane are their own products, and they can, therefore, be independent of any outside undertaking, or subject to transport and other charges for their fuel, with a consequent saving of costs and benefit to the community at large in the way of international exchange.
In particular, methane—the sludge gas of the sewage works—is a potential source of power with great possibilities, and is worthy of the necessary expenditure on digester plant for its production and use in the transport vehicles. This movement has already commenced in the London district, and is extending to the large provincial municipalities.
Local light delivery vans covering daily distances of not more than 40 miles, which are often made up of two half-day.journeys of 15 to 20 miles each, are ideal users of either town gas or electricity; the half-daily ones being quite well catered for by a gas roof-bag, and those with longer journeys than 20 miles by electric battery.
In the case of these vans it is interesting to note the recommendation of a German transport authority as follows :—Horsed vehicles, up tei 9i miles per day ; electric vehicles, up to 31 miles per day ; petrol and oil, over 31 miles per day.
A point of interest in this light-van class is that some classes of electric vans pay only £5 tax, due to the fact that the battery is not included in the taxation weight; whereas the corresponding petrol ones must pay £10.
Local goods, urban goods deliveries and urban passenger transport will be within the capabilities of liquefied methane.
There are many private cars that are used for only local transport, such as a business man to his office, a workman to and from work, a doctor's round ; also, where there is more than one car per family, which is used as a tender, for shopping, golf and social calls.
An Application of Electric Fuel Such cars can well be included in the scope of electric fuel, as the batteries are capable of carrying out such mileage as is included in the above duties.
An important and most convenient point is that the batteries of electric vehicles can be recharged in the garage at home during the night. Charging apparatus is not quite automatic and does not require the skilled assistance that used to be necessary. All you have to do is to plug the flexible connection attached to the car into the charging board fixed on the wall of the garage, and the plant itself does the rest; it arranges the rates of charge necessary at the various stages of recharging, and switches off when the battery is completely recharged. Overcharging, with consequent damage to the battery, is impossible. Long-distance private cars will come within the liquefied-methane class of fuel, as also will motorcycles, both local and long distance.
Thus, within the prescribed homeproduced-fuel limits, we account by fractionation for all types of transport and the fuel suitable for their needs.
Producer gas, town gas and electricity are well known to us as fuels; it is only their logical development for the suitable section of transport that needs attention. Methane is the fuel about which little is known, although engines have been running satisfactorily on it in sewage works.
No alteration is essential in engines to use methane, but more power will be developed if the compression ratio be increased. It is necessary to fit a gas mixer in place of the ordinary petrol carburetter. A suitable instrument exists in the conversion sets now being employed for town-gas propulsion.
Methane Gives Double Mileage Comparing methane with town gas, in the roof-bag or compressedstate, the mileage will be double per charge of gas, owing to the calorific value being twice that of coal gas.
Looking farther ahead, when gas engines are designed for methane a larger power output may be anticipated, on account of the much higher compression ratio that will be possible. The gas will be carried in its liquefied form and vaporized to its gaseous state on the way to the engine, which will make for greater efficiency of combustion than that of petrol, which is burned as a vapour and not a gas. Evidence of this incomplete vaporization is the amount of combustible carbon monoxide in the exhaust of an ordinary petrol engine. There is no combustible gas left in the exhaust of either town gas or methane, and therefore there is no danger of death resulting from running an engine in a closed garage.
It is obvious that 3,000,000 road vehicles, doing 13 widely varying duties, cannot all be working efficiently on the one fuel. Surely it is within the province of a Government's reconstruction policy to set that a much higher percentage of efficiency is aimed at than the existing haphazard and unguided one under which we suffer.