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English Document

The road to pure plant oil in diesel engines?

The chain, and brief description of the approach

This chapter briefly sketches the production chain necessary to produce PPO from rapeseed, i.e. how the crop is cultivated, processed and how it can be applied. The various ‘links in the chain’ are then detailed further in the following chapters.

The chain

Rapeseed crop

Alongside coleseed, rapeseed belongs with crops such as mustard, radish and cress in the cross-flowering category. In general, when people in Western Europe speak of rapeseed they mean winter rapeseed. The other variety (spring rapeseed) is only used in areas with very cold winters (e.g. Canada and Scandinavia) or when it is possible to sow seeds very early in the year [Van der Mheen, 2003]. Examples include southern Germany, France and parts of the UK. Finally, summer rapeseed is grown as an ‘emergency crop’, e.g. when winter rapeseed does not grow properly [Van der Mheen, 2003].

Growing and harvesting rapeseed

Winter rapeseed can be grown on rich soils with a good structure and a good water system [Bernelot Moens, 2003]. Sandy soils and those with stagnating water are not suitable for growing rapeseed. The pre-crop, for example, can also influence the crop size. Due to the early sowing time and the considerable need for nitrogen, peas and grains are also suitable as pre-crop. The plant, as an early crop, leaves behind a rich soil of mineralised nitrogen, and is therefore also a good pre-crop, for example for grains. This means that the crop fits well into existing commercial crop rotation schemes.
The plant produces seed boxes containing oil-rich seeds. These seeds are harvested as the main product – the rest of the plant is used as straw or is ploughed back into the ground, or used to cover the floors in stables.

Drying and logistics, from seed to processing

When the seeds are harvested, these are transported to a processor: either a small-scale oil press or a large-scale industrial plant. The seeds are also dried, either before or after this transport. In practice, the seeds are generally dried on the farmer’s land or in a storage facility at the processing plant.

Drying and logistics, from seed to processing

The seeds are processed into oil and a pulp, or scrap. Small-scale processing takes place via cold presses, in screw-shaped wringers. This allows around 75% of the oil in the seeds to be separated, and the rest is left as a pulp residue. However, when processing on an industrial scale, the seeds are first pressed lightly and then all the remaining oil is extracted from the pulp by means of a solvent. Both the residue from cold pressing (rough flakes) and the industrial extract (scrap) are processed in animal feeds. The flakes have the advantage that they contain the rest of the oil, which is an energy-rich additive, although the scrap has a higher protein content (35%).

Distribution from processing to end-user

The rapeseed oil produced is then distributed to (potential) end-users. With small-scale production this means transporting it from the farm where the oil is pressed to the customer.
With large-scale production transport starts from the industrial plant.

Rapeseed oil applications

Rapeseed oil is a so-called triglycerine, i.e. compounds of glycerol with higher fatty acids such as palmitic acid, stearic acid and oleic acid. Rapeseed oil is a strong unsaturated oil with a high iodine number (the same as olive oil).
Rapeseed oil is traditionally used for industrial applications, including coatings, lubrications and washing powders. The oil can also be processed into fats and chemicals. The main sales area is currently the foodstuff industry. Through the development in the 1970s of so-called‘double 00 types’ – with a low eruca acid content (R2%) in the oil and a low glucose content (maximum of 30 Smol/g) in the oil-free scrap – rapeseed oil has been used for wider applications in human foodstuffs (e.g. margarine, cooking oil. The low glucose level in the scrap means that more rapeseed scrap could be mixed with the animal fodder without damaging the health of the cattle.
In practice, rapeseed oil as a fuel undergoes a limited pre-processing that really only consists of removing the solid sections using filtration, centrifuge or sedimentation. Other applications require a more complex process in the form of decongestion, centrifuging out the lecithine (proteins), bleaching and neutralising/deodorising (removing free fatty acids)5 .

Working method

Three aspects are considered for every link in the chain:

• Technological aspects
• Environmental aspects
• Cost aspects.

In addition to these general aspects, attention is also paid to health and odour aspects for the last link, i.e. using PPO in vehicles.

Technological aspects

Technology plays a role in the various links in the chain: during actual cultivation, for the
various transport and distribution movements, during conversion from seed to oil and,
finally, when refuelling the vehicle. These various aspects are discussed in the heading
‘technology’ in each of the following chapters.
The information has been obtained from the literature currently available on this subject.
The knowledge available within CE, plus that of various experts in the field, has also been
included.

Cost aspects

The cost aspects have also been studied for each link in the PPO chain, also using available
literature. In particular, the study by [Janssens, 2004], which was concluded only recently,
formed an important basis for the cultivation costs. Various sources were used for the
logistical and transport costs, including the in-house knowledge at CE and that of other
experts.

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