With fuel prices sky rocketing these days, it’s no wonder that automobile manufacturers and motorists alike are looking for maximum fuel economy. Car makers are launching smaller-engined, more efficient models while people are getting used to the fact that modern, technologically-advanced smaller engines can be just as good as older, much larger ones. The fuel of choice is also seeing a change of preference. Diesel fuel, which used to be seen a dirty carbon-spewing truck fuel, is now being used in state-of-the-art engines of all the luxury brands like BMW and Mercedes which at times even outperform their petrol-fuelled equivalents. But the fact remains that diesel too is a fossil fuel which is a scarce resource we need to be less dependent on in the future.
Another aspect is emissions. With the threat of global warming and climate change, research and development for alternative fuels is on full swing and car makers and people alike have found new ways to mobilise their vehicles. Bio-fuel and bio-diesel are both gaining popularity. The former is sold as E85 on a growing scale. E85 is 85% ethanol blended with 15% petrol. It leads to cleaner emissions and better combustion, but slightly lower fuel economy; not a bad trade off in most cases. However, of the two, the more important one is bio-diesel.
Diesel and Bio-diesel
Bio-diesel is a fuel that can be had naturally with minimal processing requirements. Diesel is a more viscous form of fuel as such and also has a lower flash point; meaning it combusts easier under high pressure. This is the basis of the functioning of compression ignition engines.
A modern diesel engine features ‘direct injection’ technology, usually further boosted by a turbocharger, lending it a TDi designation. As compared to older diesel engines which used a pre-chamber before actual combustion (indirect injection), a direct injection engine uses an injector to inject fuel under a high pressure directly into the cylinder. This causes more efficient and cleaner combustion and also delivers better power output.
In essence, diesel is a form of oil and diesel engines are often referred to as oil-burners in most auto magazines. This gave quite a few people the idea that vegetable oil can be used to run a diesel engine. Many manufacturers have since experimented with this concept. For a significant trial period, Mercedes-Benz ran a C220 CDI model on bio-diesel in India. This bio-diesel was prepared from the oil obtained from Jatropha seeds, which were planted in abundance in the vicinity for the project. The results were rather startling – cleaner emissions, low noise levels and comparable fuel economy meant it was indeed possible. The down side was the creation and supply operation becoming mainstream and the feasibility of its production and supply based on obtaining raw materials.
Running Your Car on Vegetable Oil
After several attempts, there are many who have successfully converted their diesel cars to run on vegetable oil. The safest way to proceed with running your car on vegetable oil is as follows:
- The car used should preferably have a modern diesel engine. Any direct injection engines or TDI engines should be fine. Common-rail direct injection engine (CDI, CRDI or various badges with related anagrams) need greater care, but can be compliant. For this purpose, a turbocharged direct injection diesel engine shall be considered. What is essential is that it should not have rubber seals.
If the car is quite old chances are it may have rubber seals and the use is not advisable because they may end up deteriorating over time due to the oil’s dissolving properties.
- This fuel system will require two tanks of fuel for optimal operation. One is of course the original diesel fuel tank that comes with the car. The other would need to be installed in the boot. There are conversion kits available at specific outlets and you can have a mechanic install the whole system. The second tank will hold the vegetable oil and the system will include fuel lines to carry the fuel to then engine bay as well as hoses to carry heat. This requires a heat exchanger which uses heat from the radiator. For the oil to be run properly, it must be heated to get it to the right density for passage through the fuel filter and then the fuel injectors.
There are several fuel filters available for vegetable oil as fuel rated anywhere as high as 30 microns; but for modern engines, the filters need to be 5 microns. For common-rail engines, it should be 2 microns! Makes like Fuel Manager offer filters for 5 microns as well as 2 microns.
- Obtaining the oil is the easy bit. Waste vegetable oil is readily available from a wide variety of restaurants. Most restaurants will be happy to let you have their waste oil as they would usually have to pay to have it recycled again. They will usually keep it ready in portable 50l containers and will be more than happy for you to take it away. Choosing your restaurant wisely can dramatically reduce the filtering hassle for you. Ideally try to find a restaurant with a high hygiene standard that changes the oil of its deep fryer weekly. If possible find a restaurant that fries animal and vegetables separately such as Nando’s the chicken restaurant chain. Because all their chicken is grilled, only vegetables are fried making for much cleaner oil.
- Used vegetable oil needs to be filtered as it often becomes thicker due to hydrogenation. It will contain vegetable or even animal fats from the food it has been used to cook. Very thorough filtering is necessary to remove water and small particles or other contaminates that would quickly block fuel filters or damage the engine fuel system. The injector pump is a sensitive component of the fuel system which is particularly susceptible to damage from the ware of small particles and is also expensive to replace. Filters of various mesh sizes need to be used in succession with the smallest and final one removing particles of 5 microns and bigger. There are various ways of filtering, one of the most efficient ones is the use of a centrifuge which spins at high speed and uses centrifugal force to separate out impurities. Vegetable oil cleaning centrifuges are readily available on the internet starting from as little as £120.
- Most oil-for-fuel adaptation systems will have a switch or valve that allows you to choose between regular diesel and vegetable oil / bio-diesel. This is to ensure that you don’t get stuck when it’s cold outside and the vegetable oil solidifies. If it’s very cold, you might want to start the engine and let it run for a few minutes on regular diesel until the engine and fuel system have reached operating temperature before switching to vegetable oil. Alternatively you can buy conversion kits which will heat the oil up in the tank and again just before it gets injected into the cylinders to ensure it operates well.
You do not have to run your car on 100% vegetable oil, in fact it can run very well on a 50-50 mix of recycled veggie oil and diesel. This will save you having to invest in a conversion kit and still allow you to benefit from free fuel! If you think you can just buy sunflower oil now and pour it straight into your tank you are right but you will notice that the price for vegetable oil in the supermarket tends to rise in line with the diesel price…
So there you have it, running your car on vegetable oil is not something too far-fetched. All it needs is a little time and investment in the initial stages. Once you have it all up and running you will never look back. And remember it’s not only about saving money but also about reducing your personal emission footprint on the environment in your bid to do your bit to create a cleaner planet for our kids.