PPO vs Biodiesel FAQ

The bigger picture – Biodiesel vs PPO

Both Biodiesel and PPO converted vehicles use plant oil as the raw material. Although it’s possible to use waste cooking oil as fuel, there are quality control issues, and if biofuel use develops as expected, there simply won’t be enough waste oil to go round. Most of the oil used for biofuels in the future will come from fuel crops. Due to the globalised nature of modern agriculture, there are already disturbing reports of deforestation in many developing countries in order to clear space to grow oil-producing palm and soya crops. It is unclear how much of this deforestation is due to growth in the use of biofuels, as plant oils are already used extensively in almost every major industry. Despite this, it is clear that environmental standards for imported plant oils may fall well short of what we desire.

The biggest difference between Biodiesel and PPO is in the production. Once extracted and filtered, vehicles that can run on PPO are ready to go. To convert PPO into Biodiesel requires an increased energy input of over 25 times (taken from figures in the Levington Agricultural report). The main chemical input in Biodiesel production is Methanol, a fossil fuel derived alcohol. Biodiesel is currently uneconomical to manufacture on a small scale, so additional road miles are needed to ferry the raw PPO and chemicals to a centralised base. The finished Biodiesel must then be transported back to the various points of sale. It is safe to say that Biodiesel manufacture has a much larger environmental footprint than PPO use.

PPO also makes sense from a local economy perspective. Biodiesel plants tend to be expensive to set up, in order to comply with the vast array of legislation that governs chemical processing. It’s not financially viable, for instance, for each town to have its own ‘micro’ Biodiesel processor. This cannot be said for PPO use. A portable seed press can create a viable road fuel ‘on the farm’, which is a genuine example of a local value added economy.

 

For an indepth analysis of the worrying outcomes of growing biofuels unsustainably click here

The following is a list of questions we are often asked. Should you have a question about the differences between PPO and Biodiesel which is not listed here, please get in touch via our Contact Us page.

A) What’s the difference between Biodiesel and PPO?

Plant oils can be used to run diesel engines. Problems occur because plant oils are generally too thick and heavy for the fuel pumps and fuel injectors to cope with. There are two ways to solve this problem – either make the plant oil less thick and heavy, or make the vehicle more able to cope with thick and heavy fuel. Biodisel has a much heavier environmental impact than using PPO. PPO makes sense for local production and represents the best possible environmental performance from any of the available biofuels.

B) Thinning the oil

The most common and well known method is to turn plant oil into Biodiesel. The oil molecule is chemically split, separating the free flowing esters from the heavy glycerol content. Biodiesel is a well recognised fuel which has a vast amount of scientific research behind it, and fuel standards are in place, along with a fledgling, but well financed and growing global industry. There is another method of thinning plant oil, which involves mixing it with a solvent such as paraffin. There is very little reliable information available about the potential emissions, engine wear and environmental footprint of this method. People who use this method tend to be individuals or small groups who are willing to ‘give it a go’. We’re not prepared to endorse this method until reliable data is available.

C) Making the vehicle more tolerant

The easiest way to make PPO thinner and lighter is to heat it. As engines produce heat when they are run, it’s entirely possible to use that heat to thin the oil. There are various methods to achieve this result, from simple systems that involve running the fuel lines containing PPO through hot radiator hoses, to highly sophisticated solutions involving improved fuel pumps, re-engineered injector nozzles and in-line heating systems.

D) What are the advantages of using Biodiesel?

Using Biodiesel is straightforward – just fill up your vehicle and drive off. Your exhaust emissions will be significantly lower, and you won’t notice any major differences in mileage or performance. Biodiesel can be mixed in any proportion with fossil diesel.

E) What are the disadvantages of using Biodiesel?

Using more than 5% Biodiesel may invalidate your vehicle’s warrantee. Biodiesel will clean out your fuel system – if there’s any accumulated crud in the tank your fuel filter will become blocked as the detritus is flushed towards the engine. Biodiesel also attacks some forms of rubber found in the fuel system of older vehicles. In some vehicles produced before 1994 there is a problem with RME biodiesel degrading rubber O-rings and can lead to engine damage. Sourcing good quality biodiesel can prove very difficult.

F) What are the advantages of using PPO?

PPO tends to be cheaper than Biodiesel. It is available in every supermarket. It’s manufacture has a much lower environmental footprint than that of Biodiesel (see above). Using PPO in your vehicle will also produce a similarly low exhaust emission to Biodiesel. PPO has the lowest ecological footprint out of all the Biofuels on the market.

G) What are the disadvantages of using PPO?

Unless you are mechanically minded, you’ll have to find someone to convert your vehicle for you. A good quality professional Conversion costs around £1400 and some people find this too expensive.

 

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