Environmental impacts of fuel utilization include critical issues such as resource and pollutant issues. The analysis on quantifying the extent should include greenhouse gas emissions and its effect to the environment. Worldwide, the demand for biofuels has been increasing dramatically. With the fast depleting fossil fuels, current initiatives to attain energy sufficiency and sustainability is being pursued with biofuels as one of the alternatives, Moreover, the utilization of alternative fuels is being proposed to address current environmental issues on global warming.
Studies on biofuels, specifically bioethanol and biodiesel showed promising results in reducing GHG emissions and in turn create a positive impact on the environment. Given the increasing demand for biofuels, benefits brought about by its utilization is expected to be significant specifically on the reduction of greenhouse gas emissions. While there are issues on land use and energy balance for biofuels, extensive research should be conducted in order to identify the most viable biofuel feedstock as well as other aspects in its production and utilization. Introduction
Biofuel refers to fuels made from biomass and primarily used for motive, thermal and power generation. The earliest experiences in combustion were with the utilization of solid biofuels for domestic needs. Later, liquid biofuels became equally valuable energy resources. Years before the discovery of petroleum, ethanol was already being used as lamp fuel. By 1860, distilleries in the United States of America produced at least 90 million gallons of alcohol per year for lighting. Vegetable oils were also found to be good home heating oils and engine fuels for stationary power systems.
Rudolf Diesel has originally invented the diesel engine to run on vegetable oil specifically from peanut. Samuel Morey developed an engine that ran on ethanol and turpentine as early as 1826. Nikolaus Otto, the German inventor who is best known for his development of a modern internal combustion engine, used ethanol as the fuel in one of his engines in the year 1860. Henry Ford’s first automobile was fuelled by pure ethanol. He also fabricated the first flexible fuel vehicle (Model T in 1903) which is fuelled by either gasoline or ethanol or by a mixture of both.
Cars and other vehicles, however, begun running on cheap crude oil or petroleum as soon as reserves were discovered in the United States of America. Nevertheless, biofuels remained important energy resources competing with imported oil in countries such as Germany and Great Britain up to the close of World War II. Biodiesel Biodiesel, classified as a renewable and biodegradable diesel fuel which is produced thru extraction of natural fats and oils. It can substantially reduce green house gas emission due to its low sulfur content. It is now commonly used in various parts of the world.
Biodiesel can replace petroleum diesel in both the transport and non-transport applications. A shift in the utilization of alternative energy resources (including alternative fuels) will change the total demand for biodiesel as well as the level of utilization in specific applications. Bioethanol “Bioethanol is a high-octane, water-free alcohol produced from the fermentation of sugar or other converted biomass. In its purest form it is a colorless clear liquid with mild characteristic odor that boils at 78oC and freezes at 112oC” (www. doe. gov. ph).
Ethanol burns more cleanly because it contains oxygen and has a high octane number, hence less carbon monoxide emissions and averts premature detonation. It burns slightly cooler, extending engine life, and promotes higher volumetric efficiency of the engine, thus, increases power. Adding ethanol to gasoline “oxygenates” the fuel so that it burns with less emissions. Most modern gasoline vehicles could operate on pure ethanol with a few basic engine modifications. “A 10% blend requires no engine modification while making a contribution to reducing emissions.
Anything more than 10% requires engine modification” (www. doe. gov. ph). The other commercial blends are E15 (U. S. A. ), E20 (Brazil), E85 (Sweden and Minnesota), and E100 (used with 4% water in Brazil and Argentina). Fuel ethanol is primarily used for land transport as alternative to gasoline in spark-ignition engines. Other Biofuels The potentials of other alcohols such as methanol, propanol and butanol can be exhaustively explored for very specific future applications that can further increase the total amount of biofuel substitute to conventional fossil and fossil derived fuels.
Methanol produced from biomass is not economically competitive at present. There is, however, an interesting possibility as alternative to hydrogen as fuel. Propanol and butanol can be produced by the action of microorganisms and enzymes. Butanol, particularly, is produced by fermentation in a process that can be modified for high net enegy gains. It has sufficiently similar characteristics with gasoline fuel such that there is high probability that it can be burned pure in existing commercial engines without modification and without any difficulty.
There are other important biofuels such as biogas, charcoal, producer gas, etc. They can be processed and utilized in accordance with the provisions of existing laws, rules, regulations and standards. Studies are conducted in order that these important biofuels can be integrated into the biofuels program in a package for both energy and socio-economic objectives. Other First Generation Biofuels The most common First Generation Biofuel is biogas which is a product of anaerobic digestion of organic materials an example of which is methane from wastes. Both the gas and digestate can be used as fuel.
The utilization is usually site specific because of the environmental implications of production. A number of big commercial farms are producing and using biogas from wastes for process heating and the generation of supplementary power. Another first generation biofuel is Charcoal which is the product of the carbonization of hydrocarbon materials including wastes. Producer gas is from the gasification of hydrocarbon feedstock. In the late seventies, this fuel was utilized as engine fuel. The gas was generated from small wood chips fed into a reactor mounted unto the vehicle.
Second-generation Biofuels “Second generation biofuels are those from lignocellulosic biomass feedstock using advanced technical processes. Being currently developed are: BioHydrogen, Bio- dimethylether (Bio-DME), Biomethanol, dimethylfuran (DMF), High Temperature Upgrading (HTU) diesel, Fischer-Tropsch diesel, Mixed Alcohols” (http://www. export. gov). Biofuels, A Preferred Energy Source The earliest experiences in combustion were with the utilization of solid biofuels for domestic needs. Later, liquid biofuels became equally valuable energy resources.
In the aftermath of the war, abundance of cheap crude oil from the Middle East brought about the reduced interest in biofuels. The oil crises of 1973 and 1979, however, brought about urgent need for extenders and substitutes, temporarily focusing attention on the indigenous and renewable biofuels. In view of the rising prices (Figure 1) as well as the uncertainty of supply of crude oil and the increasing greenhouse gas emissions, it is time for a major shift in the energy mix towards the use of cleaner indigenous renewable energy in the interest of energy security, the economy and the environment.
The start of the present decade ushered in the realization that the era of cheap fossil fuels, particularly petroleum, is drawing to a close. Figure 2 shows the historical and projected petroleum contribution to the world energy mix. The rising oil prices shall persist not only because of depletion of reserves but also because of the continuing political instability in the Middle East. Developing countries shall soon find it difficult to compete for access. There is also the matter of worsening green house gas emissions from excessive burning of fossil fuels.
Continuing dependence on crude oil, therefore, is disadvantageous in terms of national security, the economy and the environment. Figure 3 shows the projected greenhouse gases emissions from developed and developing countries based on historical human and natural emissions. In view of the rising prices as well as the uncertainty of supply of crude oil and the increasing greenhouse gas emissions, it is time for a major shift in the energy mix towards the use of cleaner indigenous renewable energy in the interest of energy security, the economy and the environment.