Comparison of palm oil, Jatropha curcas and Calophyllum inophyllum for biodiesel: A review

Abstract

The world today is faced with serious global warming and environmental pollution. Besides, fossil fuel will become rare and faces serious shortage in the near future. This has triggered the awareness to find alternative energy as their sustainable energy sources. Biodiesel as a cleaner renewable fuel has been considered as the best substitution for diesel fuel due to it being used in any compression ignition engine without any modification. The main advantages of using biodiesel are its renewability and better quality of exhaust gas emissions. This paper reviews the production, performance and emission of palm oil, Jatropha curcas and Calophyllum inophyllum biodiesel. Palm oil is one of the most efficient oil bearing crops in terms of oil yield, land utilization, efficiency and productivity. However, competition between edible oil sources as food with fuel makes edible oil not an ideal feedstock for biodiesel production. Therefore, attention is shifted to non-edible oil like Jatropha curcas and Calophyllum inophyllum. Calophyllum inophyllum oil can be transesterified and being considered as a potential biodiesel fuel. Compared to Palm oil and Jatropha biodiesel industry, biodiesel from Calophyllum inophyllum is still in a nascent state. Therefore, long term endurance research and tribological studies need to be carried out before Calophyllum inophyllum oil base biodiesel can become an alternative fuel in future.

Introduction

The increasing industrialization, modernization and development have led to high demand of petroleum worldwide. Global energy consumption in 2008 was growing from 6630 million tonnes of oil equivalent (Mtoe) in 1980 to almost double of the energy consumption which had reached 11,295 Mtoe in 2008 [1]. However, the world reserve for fossil fuel such as petroleum has been depleting and causing the price to hit new highest record of US$ 136 per barrel in July 2008 [2]. In Malaysia, the final energy consumption has risen at an annual growth rate of 7.2% from 1990 to 2008 and reached 44.9 Mtoe in 2008 [3]. The crucial challenge faced by power sector in Malaysia currently is the issue of sustainability. Besides, the world today is faced with a serious global warming and environmental pollution. The major sources of greenhouse gas (GHG) emissions are gasoline and diesel fuel from transportation sector. The world is confronted with the twin crises of fossil fuel depletion and environmental degradation [4]. Thus, there is an urgent need to find an alternative renewable energy resource that is renewable, clean, reliable and yet economically feasible. Biodiesel, a cleaner renewable fuel has been considered as the best candidate for diesel fuel substitution due to it can be used in any compression ignition engine without any modification on the engine.

Biodiesel is gradually gaining acceptance in the market as an environmentally friendly fuel and the demand is expected to increase sharply as an alternative renewable energy source in the near future. Biodiesel fuel is mono alkyl ester derived from vegetable or animal and it can be blended with diesel fuel which has characteristics similar to diesel fuel and has lower exhaust emissions [5], [6], [7]. On the other hand, the main drawbacks of vegetable oil have to overcome due to the high viscosity and low volatility which will cause a poor combustion in diesel engines. Transesterification is the process successfully employed to reduce the viscosity of biodiesel and improve the other characteristics [8]. Currently, more than 95% of the world biodiesel is produced from edible oil which is easily available on a large scale from the agricultural industry. However, competition of edible oil sources as food with fuel makes edible oil not an ideal feedstock for biodiesel production [9], [10]. Therefore, much effort is required to focus in this area to produce biodiesel from non-edible seeds like Jatropha curcas, Pongamia pinnata, Calophyllum inophyllum, etc. to become feasible feedstock for biodiesel.

Biodiesel seems to be a realistic alternative renewable fuel in the near future and this review is focus on the possibilities of using palm oil, Jatropha curcas, Calophyllum inophyllum and biodiesel in diesel engine. Besides, the fuel characteristics, processes available, production, performance and emission analysis of biodiesel are discussed by making a comparison on these three different types of biodiesel fuel.