The viability of vegetable oil fuel

Written by  Dr Ian F Thomas, FRACI CChem

Published 27 Sept 2022

I have investigated the possibility of replacing fossil fuels with vegetable oil fuel (VO). This has potential to be sustainable by being greenhouse-gas neutral. Vegetable oil crops can be planted and harvested almost anywhere and require only the simplest of processing to produce fuel. I have considered engines types, oil producing plant species and availability of land. Engines addressed are the Herbert Ackroyd Stuart oil engine, Rudolf Karl Diesel’s diesel engine and Ludwig Elsbett’s modified diesel engine designed specifically for vegetable oil use. Salt-tolerant and salt-loving halophytes are shown to be the most effective oil-producing species because they do not need to be grown on limited agricultural land. There are some 2000 non-food halophyte species available. 

I drove a 1996 3.0 litre Mitsubishi Triton utility vehicle for 45,000km under trial conditions involving town and  country travel and recording weather, traffic conditions, vehicle loading and fuel type. Fuel was initially straight vegetable oil (SVO) but following some difficulties most of the trial used a 50/50 blend of waste vegetable oil and diesel fuel, with straight diesel fuel as control. Other researchers have used blends with from 2-10% vegetable oil and almost exclusively used food oils. Little work has been done in Australia. Moreover, on-road trials are rarely performed anywhere in the world, researchers working almost exclusively in the laboratory with single-cylinder test engines. Even less research is available using fuel from oil-producing trees such as Indian Beech, Sea Almond, Indian Lilac and Mastwood.

I conclude (a) that the 50/50 vegetable oil/diesel fuel blend is viable and performed slightly better than diesel fuel alone, (b) that there are very many species of non-food oil-producing halophyte plants and trees available, and (c) that there is nowhere near enough land available to provide current world energy consumption unless we all reduce per-capita consumption and move towards sustainable populations and economies. Some engine types and halophyte species are shown. My full thesis may be viewed at


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