Potential non-edible oil resources as biodiesel feedstock: An Indian perspective

Abstract

As the world confronts a reported food shortage and rising fuel prices, scientists around the globe are scrambling to develop biofuel feedstocks that would not divert food crops to energy. It is apparent that the demand for biodiesel is expected to increase in near future and although many edible oils might be the cheapest feedstock for biofuel production. But it may not be sustainable source to meet this increasing demand. This justifies the need to use non-edible oil seeds that can be the reliable sustainable feedstock for biofuel production. Furthermore, most of the non-edible seeds bearing trees have the potentials of reclaiming wasteland and does not compete with food crop for limited growing regions. It thus becomes imperative to search for dedicated non-edible feedstocks and their suitability for biodiesel production. This paper attempts to make an assessment of current energy scenario, potential of non-edible oil over edible oils, selected non-edible oil seeds as biodiesel feedstocks, impact of biofuel on environment and future direction. Experimental analysis by different researchers on these non-edible oils showed their great potential as feedstocks for biodiesel production. This paper also reviews the biology, distribution and chemistry of selected non-edible oil seeds plants.

Introduction

The issues of climate change and energy security have become much higher priorities in modern times and the quest for sustainable energy sources in light of the environmental problems and escalating energy prices has resulted in increase global support of biofuel production as an alternative source of energy in Asian countries. Several alternative technologies are available as a solution to environmental and energy problems: biofuels, plug-in electrics, hybrids, compressed natural gas, or hydrogen-fuelled vehicles. Among these alternative technologies, the use of bioenergy is proving to be particularly attractive and viable and, therefore, is becoming an important consideration [1]. The simplicity of production and use and price advantages, liquid biofuels appear to have a head start in this race [2]. The current energy situation has stimulated active research interest in non-petroleum based, renewable, and non-polluting fuels. The growth of biofuels around the world is spurred largely by energy security and environmental concerns and a wide range of market mechanisms, incentives and subsidies have been put in place to facilitate their growth. Developing countries, apart from these considerations, also view biofuels as a potential means to speed-up rural development and create employment opportunities.

Currently, renewable energy sources signify about 14% of primary-energy consumption in the world, among which biomass being the major contributor (∼10%). It is obvious that the growth projections of the biofuel industry are likely to place enormous pressure on the environment and biodiversity in developing regions. At present the global biofuel market utilizes first generation technologies and relies mainly on agricultural food or feed crops for biodiesel feedstock. The primary cost component in biodiesel production process is the vegetable oil and their availability. Soybean and rapeseed are common biodiesel feedstock in USA and Europe. Likewise, palm is being extensively used in South East Asia. It is an estimate that even if all the edible oils are used for biodiesel production, even then they will not be sufficient for meeting fuel demand [3].

According to international energy agency, the scenario of predicted biofuel production in 2030 will increase drastically (Fig. 1). Thus, biofuels from different feedstock are seems to be the only foreseeable alternative sources of energy that can efficiently replace petroleum-based fuels in the long term. According to Fig. 2, the bioenergy supply potential in the world will be 110 EJ/year in 2050 and 22 EJ/year in 2100 [4].

Estimate indicates that biodiesel could represent as much as 20–22% of all on-road diesel used in Brazil, Europe, China and India by the year 2020. Use of biodiesel is catching up all over the world especially in developed countries. Rapid economic growth in China and India would significantly increase world demand for oil. At present, India is producing only 30% of the total petroleum fuels required. India is the fifth largest energy consumer and imported nearly 70% of its crude oil requirement (90 million tonnes) during 2003–2004, which costs about Rs. 80,000 crore every year.

In India it is an astonishing fact that blending of 5% biodiesel fuel to the diesel fuel can save about Rs. 4000 crore every year. It is estimated that India will be able to produce 288 metric tonnes of biodiesel by the end of 2012, which will supplement 41.14% of the total demand of diesel fuel consumption in India. The cost of biodiesel and demand of vegetable oils can be reduced by non-edible oils, instead of vegetable oil but India is not self-sufficient in edible oils. Therefore, there is a need to find alternate feedstocks. In order to explore additional oil resources, research work has been undertaken for screening of non-traditional oil seeds for their potential as biodiesel feedstock.

The main resources for biodiesel production can be non-edible oils obtained from plant species such as Jatropha curcas (ratanjyot), Pongamia pinnata (karanj), Ricinus communis (castor), Cerbera odollam (sea mango), Hevea brasiliensis (rubber tree), Calophyllum inophyllum (polanga), S. chinensis (jojoba), Madhuca indica (mahua) and Thevettia peruviana (yellow oleander), etc. [5]. This paper provides information about current energy scenario in India, significance of non-edible oil over edible oils and presents status and utilization of non-edible feedstocks. This paper also focuses on biology, distribution and chemistry of selected non-edible biodiesel feedstocks.