VALUABLE AOTOR FUEL NOW DANGEROU FORM OF WASTE
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THERE are much too frequent announcements of tragic occurrences such as: " Terrible explosion at — Colliery last night; hundreds of miners entombed." The greater tragedy is that the cause of the explosion is the omission to convert a bad master into a good servant. This is sheer neglect on the part , of the Nation, through its elected representatives.
Methane is the bad master; as a good servant it would prevent the further tragic loss of life now incurred by the necessity of importing liquid fuel into this country; methane would take the place of this imported fuel and release transport and personnel ear-marked to bring it from its source thousands of miles away.
There can be no denying that the failure to employ methane is a national waste. It cannot be saved under our present system of economics; there is no one sufficiently interested to do the saving.
" Will it pay us? " is the question asked by the interests who own the properties containing the possibility: The answer is " Yes! " if " us " is the Nation, and not a group of individuals. . Can this wasted methane be saved? Yes; Russia does it. She liquefies methane and uses it in the same way that petrol is used.
" But it has not been done here, and no one knows how to do it." Again the owning interests speak.
Again they are wrong; it has been done here; a car was run on liquefied methane two years ago; there are now others.
Methane Much Preferable to Producer Gas We hear of a debate in the House of Lords on a proposal to equip 50,000 vehicles with producer gas. Why producer gas? Methane can do it, and without the destruction of nearly a million tons of coal which Producer gas will require.
Producer-gas plants may cost well over £.100 each.
The total expenditure, therefore, would be some £7,000,000—a lot of money. Much less than this sum spent on methane would provide permanent supplies of methane for 50,000 vehicles. Producer-gas plants would be scrapped, and their capital value along with them, the moment war is over. Ask those forced to use them to-day.
Producer gas used in a petrol engine develops, on the average, little more than half the power obtained with petrol. Many vehicles were over-engined; that helped them when they went on to gas. In other cases it has been necessary to raise the compression ratio, or even to lower the back-axle ratio; sometimes, for particularly heavy work, both courses have been necessary. There are jobs with a combination of hilly country and heavy loads that producer gas cannot tackle at all.
In fairness, however, let us say that the only practical alternative for heavy loads and long distances is pro.ducer gas, inasmuch as there are quite appreciable numbers of plants on the roads. The proviso must be made that it is possible to run producer gas successfully only if an organization exists for the regular and thorough attention to the cleaners and filters, as well as to the producer itself. It is doubtful if more than £250,000 has, so far, been expended on producer-gas equipment. When it is proposed to spend millions, it calls for consideration from quite another angle; metilane then enters the picture.
Methane, used in a petrol engine, will give the tame power as petrol; with a raised compression ratio it will give more. With an engine specially designed for the efficient utilization of methane, it will give considerably more than petrol, but that is not of importance to us at the moment.
How Methane Can be Employed
There is-no increase of vehicle weight, no decrease in the pay-load space and no trailer. The modifications necessary are the same as those made for either town or producer gas, in the way, of apparatus for conducting the gas and air into the cylinders; for although we speak of liquefied methane, so soon as the engine suctign is applied to the liquid in the tank, this immediately becomes gas and as such is burned, with increased efficiency compared with a liquid, such as is petrol under combustion.
The low temperature of methane liquid ( –160 degrees C.) necessitates the tank of the car or lorry being in some measure of Dewar or thermos-flask construction. The technique of this condition is already known, as the vehicles referred to above were so equipped; one of them was a lorry. The requisite. temperature is actually some degrees more favourable than that of the liquid oxygen which is in use in both large and small industrial establishments the world over.
This low-temperature condition is a feature which will be pointed to as a deterrent to the use of methane in this form and for the purpose suggested. There is an alternative to this low temperature which will be discussed later.
An interesting comparison to make between producer gas and methane is that 50,000 vehicles run on producer gas would require nearly a million tons of coal per annum, whereas methane-driven lorries would not con sume a single ton of coal; they would simply use up gas that is now wasted; gas that is endangering the lives of our miners and is blown uselessly into the atmosphere, its wonderful heat energy of 1,000 B.Th.U.s per cubic foot absolutely thrown into the gas gutter, as it were.
Adsorbed Methane Under Pressure in Coal There will be criticism as to the amount of gas available. No official records have been taken of the sources and the volumes of those sources, nor of the continuity of supply. This fact will be used against these methane proposals.
The following information will clarify the general position and will narrow down the criticism to the present proposal for the 50,000 vehicles.
s In every ton of coal in situ there is stored energy in the form of adsorbed methane in excess of any energy which we obtain from the coal when mined and carbonized. This adsorbed methane exists under pressure, sometimes very high, in the coal seam. As the coal face is broken so the methane escapes; its pressure helps in the splitting up of the coal at and behind the face, and it then disperses itself in the mine workings.
The average concentration of this methane in the atmosphere of the mine workings is between 0.25 and 0.5 percent. Sometimes, owing to special and unforczeen circumstances, the average concentration is exceeded and the lower explosive limit of methane and air of around 5 per cent. is reached, with the disastrous results of which we so often hear. This point is discussed as it forms a powerful argument for the utilization of methane in such a way as to reduce the danger of the work of coal miners.
Every Ton of Coal Frees 1,000 Cubic ft.
According to Professor Ranney, of Ohio State University, and confirmed by Ivon Graham at the Swansea meeting of the South Wales Institute of Engineers, there is an average of 1.000 cubic ft. of methane in every ton of coal in the earth. This is equal to seven gallons of petrol. Coal is mined in this country in excess of 200,000,000 tons. Thus we are wasting 200,000,000 times seven gallons of petrol, equalling 1,400,000,000 gallons. What is our annual consumption of motor fuel? The S.M.M. and T. gives a figure of 1,569.000,000 gallons for the year 1938. The approximate coincidence of these two figures provides a startling appreciation IA this tragedy of waste.
With the above facts in mind any conflicting views of the quantities of methane available cease to have any importance. The criticism and disbelief will be focused on a claim as to the impossibility of harnessing this methane for use.
There are several ways of doing this; one is to collect the almost-pure methane emitted by." blowers" which occur in several collieries. Another way is to collect and separate the methane from the upcast air from the colliery ventilating fans. Both are quite practical schemes.
Tubing Seams to Extract the Gas Another and newer process comes from America, and is based upon the research carried out by Ohio University, already referred to. Horizontal holes about 4 ins. or 5 ins, in diameter are bored into the coal face. They are taken 4,000 to 5,000 ft. deep, and are controlled in direction to follow the coal seam. The holes are tubed and farther back in the seam the tubes have holes communicating with the coal through which they pass. A vacuum pump is connected which releases the pressure in the seam a and the methane flows into the tubes, being pumped to the surface to be further dealt with' as desired—in our case, liquefied. One danger may be objected to, which is that of a breakage of the large pipe through which methane is being pumped to the surface. The alternative is to put the liquefaction plant down in the mine. Not impossible, because the Russians are making their town gas in the mine, so as to obviate the need for mining coal, and for many men working• underground.
The liquefaction process can be substituted by a chemical process converting the methane into butane.
Butane liquefies itself in a closed vessel, and its temperature of liquefaction is practically 0 degrees C. This condition does away with the necessity of providing Dewar flasks for the control of excessive evaporation, and, as such, has great advantages in the actual utilization of
the fuel in vehicles, in storage tanks and transport wagons. The process is a possible one; the loss in conversion from CH, to C,H„ would probably be balanced by the evaporation loss of methane. The butane would be similar to Calor gas, which is known to many of us, and which shows up on tests on cars as a most desirable fuel. Like rna ethane it gives higher power than petrol. This is due to the higher octane numbers of both these liquefied gases, and not to any increase in calorific value, for that is negligible in the gas and air explosive mixture.
There are other places where methane is wasted; not of the order of the 100 per cent. of the coal mines, but they deserve to be noted. Coke-oven gas contains approximately 30 per cent. of methane, the other combustible components being hydrogen and carbon monoxide. Some of this gas js sold to statutory authorities for the enrichment of town gas. Some of it is blown into the air, and a part is used as boiler and furnace fuel.
It is possible to use a less-rich gas for heating purposes and to conserve the methane for more economic uses.
There are two ways of dealing with these coke-oven gases; the methane can be separated out from the other gases, in addition, the Fischer-Tropsch reaction of hydrogen and carbon monoxide—the other constituents of the gas—can be utilized for increasing the methane concentration. In this way, by a rearrangement of processes and products, we can obtain more methane for our road transport without asking for more coal to produce it.
Sewage Works are a Good Source of Methane A third source is that of sludge gas frop the anxrobic system of sewage dispersion. The methane concentration in this gas is 66 per cent., the balance being carbon dioxide, an inert component; it can be washed out under pressure if desired, but it can also be used as evolved; there are numbers of vehicles using it in this condition.
Generally speaking, methane evolved at sewage wcrks can be usefully utilized in generating the power required for driving the machinery of the processes, and in providing the heat to maintain the necessary temperature of the bacteria beds. Over and above these requirements the amount of gas produced (something less than 1 cubic ft. per day per head of population) will operate transport vehicles of the works and of other departments connected with the public authority concerned. There are, however, few sewage works using the anrobic system, and many communities would be too small for its application.
This source is therefore not of sufficient interest to make it more than a minor point in the reform advocated. Nor is the coke-oven source of anything like the importance that must be attached to the colliery resources so criminally going to waste.
Why is the Government silent on this greatest of all wastes when they urge every effort to save waste in every other quarter, in our fight for life and the future existence of our country? Germany has been using this important source of power for several years, with most satisfactory results, and nothing that has been stated in this article can convey to its fuel-research engineers any
secret information of value to them. AZOTE.