Elsevier

Renewable Energy

Volume 68, August 2014, Pages 414-420
Renewable Energy

Technical note
Fuel properties of biodiesel produced from selected plant kernel oils indigenous to Botswana: A comparative analysis

https://doi.org/10.1016/j.renene.2014.02.035Get rights and content

Highlights

  • Of the four biodiesel fuels, Schiziophyton rautanenii has the best cold flow properties.

  • Other fuel properties of the biodiesel fuels are comparable to those of petroleum diesel.

  • Biodiesel fuels tested met requirements of major international biodiesel standards.

Abstract

Fuel characteristics of biodiesel derived from kernel oils of Sclerocarya birrea, Tylosema esculentum, Schiziophyton rautanenii and Jatropha curcas plants were investigated in comparison with petroleum diesel. The fuel properties under review include flash point, cloud point, kinematic viscosity, density, calorific value, acid value, and free fatty acids. These were determined and discussed in light of major biodiesel standards such as ASTM D 6751 (American Society for Testing and Materials) and EN 14214 (European standards). The best biofuel in terms of cold flow properties was S. rautanenii, with a cloud point of 0 °C and a pour point of −5 °C. The good cold flow properties demonstrate operational viability during the cold season. The heating values of S. birrea and S. rautanenii biodiesel fuels were found to be 9.2% and 10.3% lower than that of petroleum diesel while those of T. esculentum and J. curcas were both 9.7% lower. Other fuel properties analysed demonstrate that biodiesel fuels produced from kernel oils of S. birrea, T. esculentum, S. rautanenii and J. curcas plants have properties that are comparable to, and in some cases better than, those of petroleum diesel. The results of this study indicate the feasibility of producing quality biodiesel fuel from indigenous seed oils found in Botswana. A balanced allocation of resources however needs to be established to ensure that the cultivation of these oil-bearing plants does not compete with the cultivation of food crops.

Introduction

The environmental impact of petroleum fuels, coupled with the depletion of known petroleum reserves, make renewable energy sources more attractive and justify the continued search for alternative renewable fuels. Biodiesel is among the renewable energy resources that has attracted considerable attention in recent times. Biodiesel is highly favoured as alternative to petroleum-based diesel because it is renewable, non-toxic, biodegradable, non-flammable and environmentally friendly [1]. Other strengths of biodiesel fuel include its relatively high heat of combustion (lower but closely comparable to that of petroleum diesel), high oxygen value, contributing to combustion efficiency, and minimal contribution to global warming due to its closed carbon cycle [2].

Biodiesel fuel is derived from vegetable oils or animal fats [3]. The transesterification of an oil or fat with a monohydric alcohol, in most cases methanol, yields the corresponding mono-alkyl esters, which are defined as biodiesel. Biodiesel has been produced from various sources that include palm oil [4], rapeseed oil [5], soybean oil [6], and sunflower seed oil [7]. Biodiesel has been characterized according to its properties that include density, viscosity, heating value, acid value, cetane number, cloud and pour points, and flash point. The viability of biodiesel from particular feedstock seed oil depends on such factors as availability of the raw material in commercial quantity, ease of oil extraction, the oil content (yield) of the plant seeds as well as their product (biodiesel) meeting the basic fuel characteristics for diesel fuels.

The successful introduction and commercialization of biodiesel in many countries around the world has been accompanied by the development of standards to ensure high product quality and user confidence. Some of the major biodiesel standards are ASTM D 6751 and the European standard EN 14214.

In the current study, fuel characteristics of biodiesel produced through alkali transesterification of three plant oils indigenous to Botswana and J. curcas oil grown under Botswana's natural conditions are compared with those of petroleum diesel.

Section snippets

Extraction of plant seed oil

Materials used for experimentation include matured seeds (obtained from ripened fruits) of Sclerocarya birrea, Tylosema esculentum, Schiziophyton rautanenii and J. curcas plant species harvested from Botswana's indigenous woodlands. In order to maintain oil for experimentation as close to its natural state as possible, mechanical cold press extraction method was used to generate crude oil for subsequent analyses. The mechanism for the extractor consists mainly of a piston, a multi-perforated

Results

Oil yields for different plant species, fatty acid profiles of studied plant oils, ester composition of biodiesel fuels and physicochemical property analyses results are presented in Table 1, Table 2, Table 3, Table 4 respectively, while Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 present comparative fuel properties of the biodiesel fuels and petroleum diesel.

Oil yield levels

The oil yield regarded as the actual oil content in this study is the one determined using solvent extraction method and not press

Conclusions

The following conclusions can be made from the work discussed in this manuscript;

  • 1.

    The results of this work has established that the oil bearing seeds of S. birrea, T. esculentum, S. rautanenii and J. curcas plants that are native to Botswana are potential feedstock for the production of quality biodiesel since fuel properties of their derived biodiesel meet major international standards for biodiesel.

  • 2.

    Of the four biodiesel fuels, S. rautanenii has the best cold flow properties. Other fuel

References (24)

  • E. Akbar et al.

    Characteristic and composition of jatropha curcas oil seed from Malaysia and its potential as biodiesel feedstock

    Eur J Sci Res

    (2009)
  • A. Joshi et al.

    Physicochemical characterization of seed oil of Jatropha Curcas collected from Dehradun (Uttarakhand) India

    Int J Appl Biol Pharm Technol

    (2011)
  • Cited by (19)

    • Cell density, Lipidomic profile, and fatty acid characterization as selection criteria in bioprospecting of microalgae and cyanobacterium for biodiesel production

      2020, Bioresource Technology
      Citation Excerpt :

      Cold or low temperature operation of the fuel is governed by CFPP (cold filter plugging point), CP (cloud point), PP (pour point) and however, no standard boundary has been formulated by American, European, Indian biodiesel standards (Mathimani et al., 2017c). Better pour point specifies greater operation in low temperature location while poor pour point may result in certain operational issues namely settling and plugging of filters owing to the saturated fatty acid precipitation under cold temperature (Gandure et al., 2014). In addition, substantial quantity of MUFA seen in all the three strains makes the biodiesel suitable for fuel application; because MUFAs do not possess bis-allylic carbon in their hydrocarbon chain for autooxidation (Mathimani et al., 2016).

    • Optimized transesterification reaction for efficient biodiesel production using Indian oil sardine fish as feedstock

      2019, Fuel
      Citation Excerpt :

      Biodiesel technology moves over to commercialization phase from development phase. Commercialization of biodiesel will be successful only if the quality standard of biodiesel is improved at an affordable cost to meet customer’s needs [12,13]. The feedstock cost shares 75–80% of the total cost of biodiesel.

    • Central composite design (CCD) optimization of phytohormones supplementation for enhanced cyanobacterial biodiesel production

      2019, Renewable Energy
      Citation Excerpt :

      In this study, Anabaena sphaerica MBDU 105 and Nostoc calcicola MBDU 602 showed highest CP and PP in Run-12 and Run-6 with the value of about (14.1 °C and 15.3 °C) and (8.5 °C and 9.7 °C), respectively which indicates good low temperature operation characteristics. As per Gandure et al. [65] good pour point indicates better operational viability during the cold season and poor pour point leads to operability problems such as settling and plugging of filters due to the precipitation of saturated fats. Biodiesel oxidation stability can effectively be estimated by APE and BAPE (Knothe, 2002).

    • Pyrolysis gases produced from individual and mixed PE, PP, PS, PVC, and PET—Part II: Fuel characteristics

      2018, Fuel
      Citation Excerpt :

      Studies into the characteristics of alternative fuels is an important and necessary research direction. Published work has dealt with the properties of various alternative fuels, particularly biodiesel [10–18], bioethanol [19,20], biochar [21,22], hydrochar [23], and hydrogen [24]. Some publications have focused on the fuel characteristics of pyrolysis products.

    View all citing articles on Scopus
    View full text