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Gas in modern New Zealand

by J. S. Hungerford

The Manufacture of coal gas was one of the first chemical Industries established in New Zealand and has had a long and chequered career since first established as a commercial operation in England in 1798. The initial use for gas was for the purpose of lighting halls, theatres, homes and streets, and later for heating and cooking.

When the industry was established in New Zealand over 100 years ago. gas was largely used for street lighting but was soon superseded by the introduction of electricity for this purpose. It is interesting to note that the advent of plentiful supplies of cheap natural gas in the Americas created a ready demand for domestic external gas lamps.

The gas industry today is progressing rapidly throughout the world, except in New Zealand, and modern methods of gasmaking. where natural gas is not in use, make full use of automation and recent scientific discovery. In New Zealand, however, the industry has been struggling to remain in existence, gas has become unpopular with the public and is thought to be archaic.

An attempt will be made to explain why this has come about, and why it is to the national advantage to retain this industry. The discovery of natural gas in New Zealand and its probable pipelining and reticulation in the near future will allow the gas industry to obtain its rightful place and grasp a larger share of the market for energy in this country.

Problems of the New Zealand Gas Industry

New Zealand's gas industry has been based on the traditional methods of coal carbonisation in refractory retorts such as were used in Britain. This type of equipment is suited to particular coal only and prior to the last war gas coal was imported from Newcastle, Australia. As a war measure this importation was stopped and blends of different types of New Zealand coal from the West Coast fields in the South Island were and are used for gasmaking.

Unfortunately, there is no one New Zealand coal, available in quantity, suitable for use in the gas plants situated in the four main centres. The use of blends of New Zealand coals creates a number of operating difficulties.

The industry has not, however, been free to adopt newer types of more economic gasmaking processes based on oil and successive governments have insisted that coal remain the chief material for gasmaking in New Zealand. Apart from the unsuitability of local coal, carbonisation today suffers from the following disadvantages: very high plant cost, very high coal cost and high freight costs, plus high labour requirement. It has been said that there will probably not be another large coal carbonisation plant built anywhere in the world.

The by-products of the carbonisation process, coke and tar, which enter into the economics of gas production are also becoming increasingly difficult to dispose of. Coke is losing ground to more convenient piped fuels and tar is being swamped by the ever-larger and cheap sources of refinery-produced bitumen.

In the postwar years, whilst large new areas were being opened up for state housing, gas was completely excluded. In later years, because of the rapid rate of growth of electricity consumption and the very large capital involved, it became necessary to foster the gas industry by subsidy to allow it to not only remain in existence but to encourage expansion. The unfortunate state of the industry today has arisen because of the lack of co-ordination of planning for an integrated supply of energy on a national basis. A Ministry of Fuel and Power would have prevented the present situation.

Most of the gas used today is for domestic purposes and nearly 60 per cent of the country's electricity is used domestically. Gas is used mainly for space-heating, water-heating and cooking, for which purposes it is better than electricity. Gas has had to face severe tariff competition from cheap hydroelectric power, and the power authorities' policy of reducing the costs of domestic power at the expense of industrial and commercial electricity has not helped the gas industry. Gas cannot compete with electricity for lighting and power, but for industrial use both have certain definite advantages in particular Industries.

Gas or Electricity?

Because, in the past, New Zealand has had an abundance of cheap hydro-electric power the gas industry has not been able to compete even in its traditional markets for heating. At present gas sales in New Zealand represent only 7.5 per cent of the total electrical sales, whereas in Britain, where both industries are based on fossil fuels, gas sales are equivalent to 62 per cent of the total electrical sales.

Already in New Zealand, and to a greater degree when; more fossil or nuclear fuels, are used to generate electric power, gaseous energy can be produced at lower capital cost than electricity. For example, from the most recent Government statistics, the capital investment in the Gas Industry per equivalent electrical unit sold annually is only 3id compared with the electrical investment of over 12d per unit.

Gas, of course, has another big advantage over electricity in that it can be stored in gasholders against peak demand and so can cope with outputs of larger than installed capacity.

If gas production were terminated it can be easily calculated that electricity generating capacity would need to be increased by at least 20 per cent. In Wellington, for example, the maximum electrical load is of the order of 115.000kw, and the gas company load in equivalent units is around 60,000kw.

Capital investment per unit produced is, in the new type gas plants, much lower than for carbonising plant, also the efficiency of conversion of fossil fuels to gaseous energy is of the order of 80 per cent compared with 30 per cent for conversion to electrical energy.

Fossil fuels, coal and oil, and nuclear fuels and natural gas are wasting assets and may be used only once. A basic law of science says that man can neither create nor destroy energy—he can only change its form. Unfortunately, there is no natural law that prevents man froml wasting energy. The only reasonable viewpoint if oil or natural gas and even coal have to be used for power production is to convert to gaseous energy and use these fuels to the greatest efficiency. There are, therefore, three basic reasons for the pipelining of Kapuni gas as a premium fuel:

1.—Electricity which could be generated from Kapuni gas would make only a fraction of the usable energy available. (See later table.)

2.—To compensate for this lost energy, large amounts of additional fuel—most of it imported oil, incidentally —would be required.

3.—A much greater commitment of public funds to electricity generation and transmission would be needed—additional money which would not need to be spent at all if the gas is used as gas.

The above concepts involve an overall change in attitude of Government and in the mind of the public. As far as Government is concerned, a co-ordinated fuel policy under the direction of a Minister of Fuel and Power is necessary and, secondly, the public need to be encouraged in a new attitude towards gas for heating. The public has been led, for too long in this country, to the concept of a one fuel home and has come to believe gas is an oldfashioned fuel. In Australia, England, America and Europe the public know gas as a high-speed, modern fuel, and use it to a much greater degree than in New Zealand.

Manufactured Gas—Based on Coal

The original method of gasmaking, and still the main method although rapidly being superseded, was to distil or carbonise coal in a firebrick retort. In small works the retort is made horizontal and coal is either hand or machine charged. In larger works the retorts are vertical and coal is gravity-fed in a continuous process. Besides producing a crude gas. which has to be purified before distribution, coke, tar and ammoniacal liquor are obtained as by-products. These plants do not lend themselves to automation and require a long period of six to eight weeks to bring into operation from cold condition.

To overcome these disadvantages, another type of process, called the water gas plant, was introduced early this century, and this is easy to automate and can be

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brought into operation at short notice. This process is generally common in larger and is used to cope with peak demands for gas usually brought about by rapid changes in climatic conditions.

The water gas process makes gas by the reaction of steam with incandescent coke. The calorific value or heat content of this gas is lower than coal gas and is adjusted higher by the admixture of vaporised and thermally cracked gas oils. Because of its different composition and combustion properties the proportion of water gas that may be mixed with coal gas is limited to around 30 per cent.

Manufactured Gas—Based on Petroleum Feedstocks

In later years, due to changes in oil refinery operations, products have become available to the gas industry. which allow fully and semiautomatic gas manufacture operations. It is on these products, naphtha, refinery flare gases, and liquid petroleum gases that the modern gas manufacturing industry is based. These three products, which all have high calorific value—about 1200Btu per cubic foot in the vapour state compared with coal gas at 450-500 Btu, may all be admixed with coal gas in small proportions only, due to vastly different physical properties, without upsetting the combustion characteristics of town's gas. However, by a process called catalytic reforming the properties of these materials are altered and the end product is a gas very similar to coal gas, with which it may be mixed in any proportion to give an acceptable town gas.

For the extension of existing manufacturing plant, replacement of coal gas retorts, and for new gasworks generally, these catalytic reformertype plants are being built all over the world and in New Zealand there are five of these reformer plants already in operation. In principle, the reforming process is to pass the petroleum product n gaseous form through a bed of catalyst held at a high temperature, and a degradation takes place, producing as an end product simpler components, mainly Carbon Monoxide and Hydrogen gases.

Town's Gas

Town gas from larger works in New Zealand may be a mixture of gases from up to five different processes. Each of these has different properties and the final blend making the town's gas must have combustion properties suitable for use in the consumers' appliances. The required properties for town's gas are that it must burn in non-aerated burners without: carbon formation and in aerated burners without lighting back. The flame must not lift off either of these burner types. All these manufactured gases have a property of high flame speed as opposed to natural gas and' liquid petroleum gases which have low flame speeds and higher calorific value and specific gravity.

It is because of these essential differences In physical characteristics that the latter gases cannot be burned in existing appliances using manufactured gas. Manufacturers, therefore, require to know the essential properties of a town's gas in any area so that they may provide apparatus with suitable burners for that type of gas. For example, the existing appliances are not able to use natural gas or "bottled" liquid gases without major adjustments to their burners, and in some cases replacements of these are necessary. This is done by the undertaking at no cost to the consumer when a major changeover is made from manufactured to natural gas.

Natural Gas

In many parts of the world the discovery of natural pas has changed the whole pattern of energy production. Leading fuel economists in the United States have staled, on many occasions, that there has been no single factor more responsible for the upgrading of the American economy over the past decade or so than natural gas. The natural gas strike in Southern France was of such tremendous economic importance that it enhanced that country's bargaining powers in the European Common Market negotiation.

In Australia, the advent of the natural gas era is being welcomed with growing enthusiasm, and plans are well in hand for its early use from the offshore wells in Gippsland. The Kapuni field alone will not revolutionise the energy pattern in New Zealand—but it provides a very substantial addition to the country's total energy supply And there is no reason to believe that other sources of natural gas will not be discovered locally. Figures supporting the estimate that over two and a half times as much total useful energy could be delivered to consumers from the Kapuni field. in the form of gas than in the form of electricity, are shown in the following table:

Conversion of Appliances to Use Natural Gas

As indicated earlier, all existing appliance burners need to be converted. The cost of this conversion, estimated at about £10 per consumer, is borne by the gas undertaking. Although the conversion of all the gas appliances on an entire distribution system is a major operation, established procedures which have been developed overseas ensure that the gas supply to indivldual consumers is interrupted completely for only two or three hours on one day.

The Future of the Industry

The future for this industry in New Zealand is an interesting and expanding one. Kapuni supplies when piped through the North island will last for 26 years. The tremendous new gas fields being found and brought into production all over the world could supply this country's needs in the form of liquid natural gas. which could be used in the proposed pipeline if no further local gas fields are discovered. Already Britain is importing 10 per cent of her total gas supply in the form of liquid natural gas from Algeria.

For the South island, and in North island areas not on the pipeline route, sufficient liquid condensable gas will be produced at Kapuni during the initial treatment and processing, prior to entering the pipeline, to meet their whole requirement.

The use of coal for gasmaking is dated, and Kapuni or no, the industry must become more dependent on imported liquid gases and petroleum products which may be reformed for use In existing distribution systems or pumped directly into a pipeline grid system for direct use. The discovery of natural gas as a far superior replacement to manufactured gas has brought about a sudden renewed interest in a type of fuel which has been in use in many parts of the world for more than a century—and it has led to a whole new field of domestic appliance development.

Automatic ignition of gas flames by the piezoelectric principle is Just one of the many new developments taking place in the gas appliance field. The advent of tnermostatic control has also revolutionised the concept of the domestic gas appliance.

One of the heating systems in common use overseas which local gas appliance manufacturers are now looking at with considerable interest is the central heating of homes by gas.

The principle of total energy—as embodied in the newly-developed gas fuel cell which produces electricity—is now being applied throughout the United States and Canada in office buildings, shopping centres. hotels, motels, apartments, industrial plants, hospitals and, most recently of all, in schools. With natural gas service, there is the possibility that the gas fuel cell may also eventually come into its own in New Zealand.