The road to pure plant oil in diesel engines?

There is increasing interest, at both regional and local levels, in using pure plant oil (PPO) as a fuel for road vehicles. This is confirmed by the various initiatives taken by various local authorities, provincial bodies and private individuals. PPO is a possible replacement for diesel, and is currently popular with both the general public and politicians, partly as a regionally implemented solution to climate change and other environmental problems. In practice, both the Netherlands and Germany concentrate on rapeseed oil, produced from rapeseed that is cultivated as a green fallow crop.
Very little is known about the actual environmental advantages and costs relating to the implementation of PPO. It is also not clear which applications are most suitable for PPO use, which criteria these applications must meet (both vehicle and fuel) and which other technical aspects play a role, e.g. storing PPO.
SenterNovem has commissioned this report in order to fill in the current gaps in this knowledge. This study covers the following aspects:

To what extent is PPO technically developed as a transport fuel?
To what extent do engines need to be modified in order to run on PPO?
Which costs are related to the use of PPO, and who will pay these costs?
Which environmental advantages (or disadvantages) are associated with the use of PPO as a vehicle fuel?

To a certain extent this study complements the ‘fact-finding study’ [Broek, 2003] implemented by Ecofys in 2003, in which these aspects, particularly biodiesel and bioethanol from agricultural crops, were researched.

Methodology

Where possible, the research team have based the study on practical data. The main sources of information include trade literature, reports on the practice of producing and using PPO as a transport fuel, plus verbal advice from experts in the field.
This study primarily focuses on producing PPO from rapeseed, partly because this is by far the most-used crop for PPO initiatives in the Netherlands and Germany. The scope of this report covers the cultivation of rapeseed in the Netherlands and Germany, and the use of PPO for cars in the Netherlands. The timeframe chosen covers the period from 2005 to 2010.
The study includes relevant statistics for costs and the environment, where these are representative for the current cultivation and processing of rapeseed.
The results appear to be very sensitive, particularly with respect to cultivation aspects such as yield per hectare, N2O emissions during cultivation, and oil content of the rapeseed. The research team has therefore specifically chosen not to use average result figures. Instead, the team defined the outer limits between which the results could vary as a function of:

The rapeseed yield per hectare (3 – 5 ton/ha);
The oil content of the harvested rapeseed (40-45%);
The N2O emissions from fertiliser used during cultivation (a range, as stated in the IPCC
guideline);
The technology used to extract plant oil and the efficiency with which the oil is isolated:
- a) Large-scale: pressing and extracting with >98% return;
- b) Small-scale, pressing with ± 75% return

These aspects are very important in determining the specific costs and environmental impact per unit of PPO. Uncertainties concerning fuel consumption of agricultural vehicles, due to differences in local soil conditions, machines, chauffeur driving styles etc., are not included here.