Examination of Pure Plant Oil as a Transportation Biofuel – Experiences and Potentials

Pure plant oils have been shown to offer great promise as a transportation biofuel. A European Parliament report [3] that examined biofuels before the biofuels directive was finalised stated “Because of its non-toxic nature and its allowance for smaller refining units, this approach would probably bring the greatest long-term benefits in terms of regional development, environmental balance and job creation.” However this option is often discredited due to experiences when operating plant oils in diesel engines. A growing number of studies have examined its usage. Unfortunately the results of these studies have been mixed largely due to variables in both fuel characteristics and engine optimisation.

As an example the Department of Transport commissioned study [1] cited in the consultation papers last summer would at face value show that rapeseed oil fuelled cars have greater emissions than vehicles fuelled with diesel fuel. Examination of this study by someone with experience of the technologies and issues involved shows that the equipment fitted and adjustments made to the vehicles to allow rapeseed oil usage were not sufficient to provide optimised operation. The rapeseed oil used as a fuel was not tested to ensure that its properties were suitable for use as a diesel engine fuel; some properties of relevance were tested and found to be within levels considered appropriate. Other important variables which would affect combustion and reliability were not tested.

Emissions from the use of PPO have also been examined in a recent literature review compiled on behalf of the Dutch government [2]. This review examined a number of different recent studies and drew the conclusion that when PPO tailpipe emissions were compared to those of diesel fuel there were no clear differences except for reduced NOx.

Also concerns about reliability in diesel engines are often cited. However numerous properly converted vehicles have been shown to operate reliably. German experiences have shown PPO to be a viable alternative with many possible advantages over alternatives [4]. In Germany a fuel standard has been created by a partnership between industry and academia, the German government is now looking at adopting this standard to further promote developments. It has often been stated that if vehicle manufacturers
were encouraged to produce vehicles with engines designed to handle PPO that uptake would be encouraged due to the negation of the expense of conversion. It has been calculated that if engines were produced with PPO capability the costs would be greatly reduced.

Support for PPO in the UK is limited and it appears the government has received little in the way of solid information on the prospects of this biofuel. This would appear to be largely due to the lack of industry interest in this fuel; currently there are a very limited number of small firms involved in these technologies. The suggestion would be that the financial incentives are insufficient to promote its usage despite possible advantages over other options. There has also been much confusion over the tax position of PPO which has slowed uptake.

Results of comparisons between different renewable alternatives generally frame biodiesel (which shares many factors with PPO production) using current intensive chemical heavy input crop production and large scale mill oil extraction. These variables could be significantly improved by the adoption of less intensive crop production (eg. using organic farming methods) and the use of small scale presses which have been proven to be able to supply quality fuel with good overall economic and environmental performance. This allows fuel transportation to be greatly reduced as fuel can be grown and produced close to point of use. Obviously this is a ‘best case scenario’ but these methods are growing in popularity both in Germany and other EU member states. Cold pressed locally distributed rapeseed fuel has been shown to have an energy balance of 24.85:1 and a CO2 balance of 14.44:1 [5].

There is also a large potential for the use of other oil crops. Oil based biofuel production has concentrated on feed stocks from readily available food oils. There are a huge number of oil producing plants that could potentially provide a suitable fuel oil and may well lend themselves to better methods of cultivation and better yields; algae is often cited, tree and shrub crops can produce high yields with reduced cultivation inputs, mixed plantings of oilseed and other crops have been shown to provide good yields.

[1] Dft Biofuels Evaluation – Final Report of Test Programme to Evaluate Emissions Performance of Vegetable Oil Fuel on Two Light Duty Diesel Vehicles http://www.dft.gov.uk/stellent/groups/dft_roads/documents/page/dft_roads_027622.pdf

[2] Compatibility of pure and blended biofuels with respect to engine performance, durability and emissions - SenterNovem http://www.novem.nl/default.asp?menuId=10&documentId=150024

[3] Report on the proposal for a Council directive amending Directive 92/81/EEC with regard to the possibility of applying a reduced rate of excise duty on certain mineral oils containing biofuels and on biofuels(COM(2001) 547 . C5-0030/2002 . 2001/0266(CNS))
Committee on Economic and Monetary Affairs

[4] BioDiesel and Pure Plant Oil Examination of the Effects of German Biofuel Uptake Prof. Dr. Ernst Schrimpff Fachhochschule Weihenstephan University of Applied Sciences

[5] Note:Rapeseed Oil for Transport 1: Energy Balance and CO2 Balance-Based on EMBIO, The Danish Energy Agency’s Model for Economic and Enviromental Assessment of Biofuels Jacob Bugge Folkcenter for Renewable Energy-Denmark2000

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