H.—34b.

The consumption figures for New Zealand since 1928 are as follows :—

New Zealand Consumption of Petrol, in Millions of Gallons.

The value of the imports of petrol and crude oil into New Zealand for the same period were as follows (the values represent the current domestic values in the countries of export plus 10 per cent.):—

Manufacture of Petrol from Coal. It is well known that the demand for coal in New Zealand is decreasing, and while it is possible that with the general revival of trade the demand may rise, the industry has had to face the position that unless there is a large increase in population or unless new uses are found for coal the demand may not be so great as in the past. The reduced demand is partly the result of more economic use in power production, partly the competition of hydro-electric power, and partly the increased use of oil owing to its greater convenience, particularly in shipping. Under New Zealand conditions, except when convenience is a very major factor, coal (or gas) is still pre-eminently the most economic source of domestic or industrial heating, but for conversion into mechanical power for mobile units oil is undoubtedly the most satisfactory fuel. Oil may be obtained from coal by three different processes—namely, high-temperature carbonization, low-temperature carbonization, and hydrogenation. High-temperature Carbonization. This is the usual process operated at gasworks, where coal is carbonized at temperatures of from I,ooo° to 1,400° C. While gas and coke are the main products, a small amount of light oil is obtained by distillation of the by-product tar. This does not exceed half a gallon of benzole and naphtha per ton of coal carbonized. It is possible to recover a further quantity of benzole, suitable for use as motor-spirit, from the gas by the use of a wash oil, or by means of absorbent carbon. This further quantity does not exceed 2to 3 gallons per ton of coal carbonized. The process is in operation in many places in Great Britain and the Continent, but not yet in New Zealand. Only the largest gasworks in New Zealand could install the requisite plant, and if they did so approximately 400,000 gallons of benzole would be recovered per annum. This represents 0-75 per cent, of New Zealand's consumption of motor-spirit. Even this would increase the coal used for carbonization by 8 per cent., and would provide employment for an additional sixteen men at the works and approximately forty at the mines. Recovery of benzole from coal-gas in the Dominion would therefore appear to warrant some encouragement. Low-temperature Carbonization. Coal can also be treated by carbonization at lower temperatures—say, from 450°-700° O, and the main product, if bituminous mixtures are used, is then a free-burning, smokeless coke suitable for use in the domestic grate and comprising up to 75 per cent, of weight of the coal carbonized. In this case there is also a good yield of tar, about 20 gallons per ton of coal carbonized from certain classes of coal, with gas as a subsidiary, but yet an important by-product. If sub-bituminous non-caking coals such as Waikato or Kaitangata are used the yield of tar is somewhat less, being from 16 to 17 gallons per ton, and the carbonized residue, amounting to 55 per cent, of the coal treated, must be briquetted for domestic purposes. From both the tar and the gas it is possible to obtain a spirit which, after refining, is suitable as a motor-fuel. That which is contained in the tar may be obtained by " fractional distillation "— that is, by heating the tar, separating the vapours given off, and condensing them. The spirit is recovered from the gas by the process of " scrubbing," similar to the method of obtaining benzole from the town gas.

2

Tiv Mot™- By other Means Year. Vehicles (Engines Aero- Total. planes, Sec). 1928 41-45 2-0 43-5 1929 .. .. .. .. 56-6 3-6 60-2 1930 .. .. '.. .. 62-8 3-9 66-7 1931 .. .. .. .. 55-2 5-2 60-4 1932 49-8 5-4 55-3

Crude Petroleum, Crude Residual Calendar Year. Motor-spirit. Oil, Once-run Shale Oil, and Crude Distillate of Petroleum. £ £ 1928 1,655,000 447,000 1929 2,131,000 328,000 1930 2,090,000 498,000 1931 1,243,000 417,000 1932 1,116,000 373,000