Environmental aspects and challenges of oilseed produced biodiesel in Southeast Asia

Abstract

Research on alternative fuel for the vehemently growing number of automotivesis intensified due to environmental reasons rather than turmoil in energy price and supply. From the policy and steps to emphasis the use of biofuel by governments all around the world, this can be comprehended that biofuel have placed itself as a number one substitute for fossil fuels. These phenomena made Southeast Asia a prominent exporter of biodiesel. But thrust in biodiesel production from oilseeds of palm and Jatropha curcas in Malaysia, Indonesia and Thailand is seriously threatening environmental harmony. This paper focuses on this critical issue of biodiesels environmental impacts, policy, standardization of this region as well as on the emission of biodiesel in automotive uses. To draw a bottom line on feasibilities of different feedstock of biodiesel, a critical analysis on oilseed yield rate, land use, engine emissions and oxidation stability is reviewed. Palm oil based biodiesel is clearly ahead in all these aspects of feasibility, except in the case of NO_x where it lags from conventional petro diesel.

Introduction

Demand of transport fuel is growing rapidly all over the world. Among all automotives, diesel run vehicles are becoming more popular day by day because of its superiority in fuel efficiency [1] and low emission of CO₂, CO, HC [2]. The diesel engine is invented by Dr. Rudolph Diesel and run by peanut oil at the Paris Exposition of 1900. So it has been established from then that, high temperature of diesel engine is able to run on variety of vegetable oils [3]. Today diesel-powered vehicles represent about one-third of the vehicles sold in Europe and in the United States it is predicted that diesel run automotives will rise from 4% (2004) to 11% by 2012. Being alternative for petro diesel in transportation sector, biodiesel leads to the easiest and most crucial solution for environmental problems as it does not require any engine modifications and reduces greenhouse gas (GHG) emission substantially as well as improves lubricity. This makes it more adaptable to current energy scenario to ensure energy security, environmental sustainability, and boost rural development by shifting of power from petro to agro-industry, simultaneously.

By using raw vegetable oils as fuel many engine problem evolved like coking of injectors on piston and head of engine, carbon deposits on piston and head of engine, excessive engine wear [4], [5], [6]. To compensate this problem, most researchers [5], [7], [8] have recommended using transesterification of vegetable oils to reduce viscosity. This transesterified vegetable oil is termed as biodiesel. Transesterification is an esterification process of long chained triglycerides of vegetable oils into fatty acid methyl esters (FAME) which is coined as biodiesel. So far, many vegetable oils have been used to produce biodiesel viz. of peanut, rapeseed, safflower, sunflower, soya bean, palm, coconut, corn, cottonseed, linseed. Also some non-edible oils like Mahua, Neem, Karanja and Jatorpha came into lime light after the fuss of food vs. fuel debate worldwide. But this debate lost its ground as most of the government policies permits only 5–20% biodiesel blend (B5–B20) with petro diesel. Biodiesel have proved its technical soundness in low percentage blending by the field trials and experiments carried out by researchers in last decade.

Malaysia and Indonesia are respectively largest and second largest producers of palm oil in the world, jointly they produces 85% of world's palm oil. In Southeast Asia (SE Asia) biodiesel production is drastically rising due to its high potentiality and yield factor of palm. Tropical climate and cheap man power of this region is another beneficial point for growing of this plant [9]. Malaysia's biodiesel production is majorly palm oil based though it has taken some initiative to introduce Jatropha production in mass level. Palm oil is derived from the flesh of the fruit of the oil palm tree Elais guineensis. Palm tree is originated in West Africa (more specifically Guinea Coast) [10] and initiated in Malaysia in 1870s as ornamental plant and in Thailand before World War II. In both these countries, first commercial plantation started in 1960s [11]. Indonesia also uses sugarcane and cassava for bioethanol production. Thailand uses molasses, cassava and sugarcane for bioethanol production. Palm is an established biodiesel feedstock in Indonesia and Jatropha is also getting importance for a yield factor of 1.2 tons/ha [12]. As this review article is focused on biodiesel, it will discuss about major biodiesel feedstock of this region only, i.e. palm oil (E. guineensis) and Jatropha curcas (J. curcas) is a large shrub or tree commonly found throughout most of the tropical and sub-tropical regions of the world. J. curcas plant is a drought-resistant, perennial plant living up to 50 years and has the capability to grow on marginal soils. It requires very little irrigation and grows in all types of soils. The production of Jatropha seeds is about 0.8 kg/m² per year [13]. It is only non-edible biodiesel feedstock of Southeast Asia. Jatropha is a potential second generation biodiesel feedstock, though it still requires vigorous research and development for commercialization.

Unfortunately only Malaysia, Indonesia and Thailand are harvesting benefits of producing biodiesel. Other countries of SE Asia are far behind in this sector because of lack in infrastructure of biodiesel production and government support for growing biodiesel producing oilseed crops. A large number of selective literatures are reviewed in order to critically compare the feasibilities of this feedstock with other popular biodiesel feedstock like rapeseed, soy, cottonseed in different parameters like land use, fertilizer use, oxidation stability, engines chemical emission, oxidation stability. On selecting references, only highly rated journals with scientific references, Society of Automotive Engineer (SAE) technical notes are taken and some information's are gathered from reports from renowned organizations like Food and Agriculture Organization of the United Nations (FAO), International Energy Agency (IEA), European Biodiesel Board (EBB), European Committee for Standardization (CEN), National Institute of Standards and Technology (NIST) and Malaysian Palm Oil Board (MPOB), Malaysian Palm Oil Council (MPOC). The experimental results as well as reasoning behind these results are analyzed to find the jest. In most cases a clear cut comparison of results are not possible, as engines were different (single cylinder, multiple cylinder, different brands) also their operating conditions (speed, load, throttle position). The variation of oil specifications of same feedstock is another important fact for this variance in result.

Palm oil turns out as most prospective biodiesel feedstock. Because palm oil has a high yield factor, low fertilizer, water and pesticide consumption and palm oil methyl ester (POME) has low engine emissions, high oxidation stability apart from NO_x emissions which is higher. Jatropha is also promising as second generation biodiesel feedstock. But it requires more research to develop its properties to a satisfactory level for mass commercial usage.