DISCLAIMER: DO NOT ATTEMPT TO POUR VEGE OIL IN YOUR VEHICLE AFTER READING THIS

It may come as a surprise to some of us Malaysians, but in countries where diesel engines are the norm for passenger cars, this is not news. Now, we’re not telling you to go and fill up your diesel vehicle with vegetable oil right after you read this. We’re just saying, this is all possible. We have been converting liquid fuel to kinetic energy for a hundred years now, and I find that to be fascinating. It gets even more interesting when engine fuel can be grown on trees. (Yes, yes... there are electric cars now… Just hear me out.)

The first diesel engine invented by Mr. Rudolf Diesel was able run on peanut oil. That was the beauty of the original intent of the diesel engine – that it was able to run on vegetable oil (a renewable energy source). It was only after the petroleum industry produced diesel fuel that diesel engines were developed to function with petroleum diesel (petroleum diesel and vegetable oil are chemically different and behave differently). The diesel engine has served us for over a century now in major modernization activities – transportation (trucks, ships, locomotives), electric energy generation, agricultural activities, and civil works. The threat to the diesel engine is the depleting source of petroleum (but news on that always changes).

Are electric motors a threat to the diesel engine?

Only in the context of the passenger car, yes. Most applications of the diesel engine don’t seem easily replaceable with an electric motor.

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So, what about this vegetable oil thing?

Diesel engines work on the basic principle of compression ignition – compress a fuel (with oxygen) with enough pressure and speed, and the fuel will ignite, releasing energy that was contained by the fuel (calorific value). This energy moves the pistons and so on to create a rotational motion. This works well with petroleum diesel (C₁₂H₂₄), but also works with other liquids such as biodiesel, Straight Vegetable Oil (SVO), and Waste Cooking Oil (WCO).

Vegetable oils that have been shown to work include Soybean oil, Jatropha oil, Sunflower oil, Karanj oil, Rapeseed oil, Palm oil, and Canola oil. Most of them have been tested both in their crude form (SVO) and biodiesel form (methyl ester produced by transesterification). The challenge here is that crude oils are viscous and biodiesels are expensive to produce.

But it still works, right?

Yes. Biodiesel works. In fact, the diesel we use in Malaysia right now contains some percentage of biodiesel. B7 (7% biodiesel) has been out for a while and the B10 (10% biodiesel) programme was launched in February this year. FYI, the biodiesel we use is obtained from palm oil, one of our most abundant resources in Malaysia.

Waste cooking oils work too, after some filtering. Although it would be advisable to have a fuel preheating system since WCO has a higher freezing point and higher viscosity.

Straight vegetable oils work too, although with some setbacks for the time being. SVOs are viscous, have low volatility, and have lower calorific value than the ordinary diesel fuel. Diesel engines will run on them, but it causes some serious wear. With some modifications to the traditional diesel car, it is possible to run a diesel car on SVO.

What good is this information?

Well, now you know diesel engines can run on vegetable oils, even the non-processed ones. Although using crude vegetable oil most probably would cause a shorter engine lifespan. If you’re stranded with a diesel car in a post-apocalyptic world, take comfort in the fact that your car can run on cooking oil, waste cooking oil, palm oil, or rapeseed oil.

On a more serious note, this means there is potential for vegetable oil to be used in diesel engines. In the context of Malaysia, it would mean less dependency on petroleum diesel since we have palm oil. It doesn’t have to go into your car, but it could go into trucks, ships, farming equipment, water pumps, and portable generators in rural areas. Of course, R&D will be required, but I think this is good news and you should know it too.

REMINDER: DO NOT ATTEMPT TO POUR VEGE OIL IN YOUR VEHICLE AFTER READING THIS