Motor fuel from gas: seven options

Press, 30 August 1979, Page 16

Motor fuel from gas: seven options

There are seven transport fuel options open to New Zealand. First, there is a projected market in Japan, and possibly the United States, for new fuels to replace oil in power generation and in industrial fuel uses. Liquified Natural Gas (L.N.G.) is already an accepted fuel in this market and fuel methanol might also be acceptable if available at • competitive prices. Thus, exporting L.N.G. is a possible means of using New Zealand’s gas to generate foreign exchange, which in turn could be used to buy oil. The high rate of gas production required would also enhance recovery of condensate. On the other hand. L.N.G. export does little to improve New Zealand’s security of supply and would rapidly deplete known gas reserves. Second, methanol-gasoline blends containing up to 15 per cent methanol (Ml 5 have been tested in New Zealand and overseas, and have been found to perform satisfactorily in gasoline-engine vehicles with only minor modifications. Problems with methanol blends can probably be overcome at an acceptable cost. Ml 5 has the advantage of involving little vehicle modification while promoting a move towards an alcoholcompatible transport system. It is thus an option which leaves all future options open. But Ml 5 is a controversial option which has attracted strong opposition as well as strong support. It has only limited potential to replace imported oil — it would replace only 10 per cent of gasoline demand at most, and this would be down to only 2 per cent if its use was confined to new vehicles. Third, compressed natural gas (C.N.G.) is a proven vehicle fuel and provides the most direct and efficient means for using natural gas as a transport fuel. But it has the disadvantage of high vehicle modification costs, it needs special refue'iing facilities. and has a limited rang®. It is Most suited to use in vehicle fleets.

It is the only alternative fuel option which has the advantage of needing no investment in processing plant. It could be introduced quite soon and in small steps. The introduction of C.N.G. has been given a high priority by the Government. There were Budget incentives for it and the Minister of Energy (Mr Birch) recently announced an official conversion target of 150.000 vehicles by 1985. Fourth, Liquified Natural Gas (L.N.G.) has attributes similar to C.N.G. with the advantage of an extended vehicle range. Major disadvantages are the very high cost of vehicle modification and the need for a large market to support the cost of a liquification plant. L.N.G. as a vehicle fuel would only be economic if associated with an exportorientated L.N.G. venture, and then only for vehicle fleets particularly suited to the fuel—these with access to L.N.G. storage, extended vehicle range, and a high annual fuel consumption per vehicle. Fifth, liquified petroleum gas (L.P.G.) has similar attributes to C.N.G. with the advantages of lower vehicle modification costs and more extended vehicle ranges. It is most suited to fleet vehicle use, but has the relative disadvantage of requiring a high capital cost for distribution and storage, and for production where large quantities of L.PG. are required. Sixth, methanol is known to be an excellent fuel and can be produced readilv from natural gas. Gas availability would allow the whole of New Zealand’s demand for gasoline to he renlaced by a mothanol M9O blend. Alcohols in genera’ are intrlnsicallv more efficient engine fuels than saso'ine so the use of m»‘hanol fin contrast to svnthetic gasoline bom natural east would e-rtond the life nf ‘he natural ga e roco»-voq sionificantlv But methanol has ‘he disadvantage of being a different fuel from gasoline and would therefore rermire substantial ennine modification or re-design.

There is much less technological effort being devoted worldwide to alcohol engine design than is being devoted to the gasoline engine. Consequently there is a possibility that the advantages of methanol fuel may not be able to be fully realised. The small size of the New Zealand market would make the production °f a . methanol engine prohibitively expensive if New Zealand adopted this solution in isolation. The results of economic analysis indicate methanol to be most suited to new vehicles specially designed for the fuel. Methanol is a potentially attractive option, in spite of the uncertainties associated with it. Seventh, synthetic gasoline production could substitute, as with methanol, for the whole New Zealand demand for gasoline. In comparison with methanol, synthetic gasoline could be introduced comparatively quickly since this option avoids the need for any subsequent modification to the distribution system and vehicle fleet. It has the disadvantage of relatively high cost and low efficiency as a way of using natural gas. Installation of a major synthetics plant would also commit New Zealand to a conventional and expensive fuel base, which could prove eventually to be inappropriate. There are two types of synthetic gasoline technology available — Fischer-Tropsch and Mobil. Fischer - Tropsch technology is well proven and enables production of moderate quality gasoline and diesel fractions. Considerable refining is needed to upgrade these fractions to meet finished product specifications. Mobil, while still commercially unproven, produces a high quality gasoline directly, but does not produce diesel at the same time. Adoption of the Mobil process would require parallel development of another alternative to overcome this diesel deficiency. The results of economic analysis show the economic performance of synthetic gasoline-diesel processes to be poor. It would superficially be more economic to export gas as L.N.G. to provide funds for the, purchase of crude oil. But this conclusion neglects to consider security of supply.

The choices for New Zealand in the development of liquid fuels were discussed recently by the technical director of the Liquid Fuels Trust Board, Mr B. V. Walker, in a paper given at a loading symposium in Wellington. OLIVER RIDDELL, in the second of three articles taken from Mr Walker’s address, considers the options open to New Zealand in using natural gas to provide transport fuels.