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The carbothermal reduction of Al2O3 under primary vacuum using concentrated solar energy is a clean process for the production of energetic aluminum. However, undesirable by-products can be formed if the physico-chemical parameters (pressure, temperature) are not optimized. In the present work, the Sol@rmet reactor has been used to perform this reaction in the following pressure and temperature ranges, respectively, 280 to 880 Pa and in between 1800 and 2200 K. In particular, at total pressures lower than 400 Pa and at temperature around 2050–2150 K, collected powders with Al content higher than 90% have been obtained (maximum achieved Al yield close to 70%). It has also been shown that the use of a binding agent (in the reactants) and/or a change of the partial pressure of CO in the reactor could have a major influence on the formed Al/CO ratio. Finally, kinetic calculations on experiments performed at 380 Pa demonstrate that the phase boundary reaction and the nucleation process dominate the first stage of the carbothermal reduction of Al2O3.

The improved solar reactor Sol@rmet allows to investigate the reduction of MgO in presence of carbon using concentrated solar energy in low vacuum conditions close to 900 Pa. The influence of the carbon type was studied and it was shown that a carbon issued from a biomass source was a great candidate. A gradual increase of the temperature during experiment allowed to obtain promising results. Powders with a high Mg content up to 97 m% and a high yield rate up to 50% were collected. Short time experiments at fixed locations under the focus of the solar concentrator were performed in order to obtain information on the kinetics of the carbothermal reduction of MgO. Notably, these experiments have underlined the temperature effect on the CO emission. 50 to 80% of the CO emission mainly occurred in 100 s after the beginning of the experiments. The phase boundary reaction between MgO and C appeared to be the dominant process at the initial stage of the carbothermal reduction. Calculated activation energy of this process is around 260 kJ mol-1.

The carbothermal reduction of MgO and Al 2 O 3 in argon flow at low pressure allows to lower the onset temperature of metal vapor formation. Thermodynamic calculations indicate that metal formation begins at 1400 and 1700 K for a primary vacuum (1000 Pa), respectively, for Mg and Al. In the experimental section, concentrated solar energy was used for the process heating in order to favor energy savings. The products of the reaction between MgO or Al 2 O 3 and 2 varieties of carbon (graphite, carbon black) in flowing argon atmosphere at a total pressure of around 1000 to 1600 Pa were studied using X-ray diffraction, and microstructure observations revealed the formation of metallic nanopowders with some by-products. Metallic conversions close to 45 wt% and 52 wt%, respectively, for Mg and Al, were obtained. The low conversion yield of the carbothermal reduction of MgO can be attributed to a backward reaction reforming MgO powder and to a sintering process between oxide particles at high temperature. Aluminum production challenge is to avoid formation of undesired by-products: Al 2 O, Al 4 C 3 and Al-oxycarbides. Advantages and weaknesses of the used process are described and some improvements are proposed to increase metallic yields.

Hafnium carbide (HfC) is a promising materials for high-temperature heat exchangers due to its high melting point (4170 K). Nevertheless, its fast oxidation into fragile hafnia prevents it from being used for open-air solar receivers. The incorporation of silicon-based compounds would reduce its oxidation kinetics and extend the lifetime of HfC-based elements. The oxidation behavior of HfC sintered with the addition of 10vol% TaSi2 or ZrSi2 is here investigated. The optical properties on the as-received surfaces and on the oxidized ones were measured, especially the ratio of the 0.6-2.8 µm emissivity (close to the solar absorptivity ?) to the total hemispherical emissivity ?. These optical properties are important parameters for applications using concentrated solar radiation

In situ resource utilization (ISRU) refers to the in situ generation of consumables for autonomous or human activities from raw materials found on the Moon or other planetary bodies. The use of ISRU on the Moon may provide a means of reducing the cost and risk of human exploration of the Moon and beyond, and an impetus for commercial contributions to lunar exploration. Potential products include O2 and H2O for life support, H2 and O2 for fuel and propellant, and other elements and compounds for metallurgic and chemical production processes. If ISRU is to be applied successfully on the Moon, it is important that landing site selection, surface operations and suitable ISRU technologies are identified using knowledge of the availability and distribution of lunar resources and detailed understanding of the workings of the various processes available. Here, we review current knowledge of chemical and mineralogical resources on the Moon which can be used in the development of ISRU as a realistic component of future lunar exploration.

The aim of this article is to discuss the properties of pyrolysis liquid products and their primary applications. The pyrolysis of biomass is a promising route for the production of solid (charcoal), liquid (tar and other organics), and gaseous products. These products are of interest as they are possible alternate sources of fuels and chemicals. Pyrolysis liquid is referred to in the literature by terms, such as pyrolysis oil, bio-oil, bio-crude oil, bio-fuel oil, wood liquid, wood oil, liquid smoke, wood distillates, pyroligneous tar, and pyroligneous acid. Bio-oil from biomass pyrolysis mainly consisted of aromatic, aliphatic, and naphthenic hydrocarbons and oxygenated compounds, such as phenols, furans, alcohols, acids, ethers, aldehydes, and ketones. Bio-oil has a higher energy density than biomass, can be readily stored and transported, and can be used either as a renewable liquid fuel or chemical production.

Wind energy is the fastest growing renewable energy source in Europe. Europe accounted for 69% of the total installed capacity and 70% of the annual market growth during 2005. The wind energy sector would have preferred a strengthening of existing, successful, legislation, and is concerned that a new legislative package could take years to adopt at a crucial time in the development of large scale wind power. The main objective of this study is to summarize the strategies and activities of the EU countries toward sustainable development goals. In addition, this paper describes the environmental and economic impacts of wind power technology in the EU.

The aim of this study is to obtain pyrolysis products (solid, liquid, and gas) from black locust (Robinia pseudoacacia) in the presence of perlite. These include oil, water-soluble products, char, permanent gases, and C1–C4 hydrocarbon gases. The yields of liquid products increase with increasing temperature and perlite. The highest yield of liquid products was 61.9%, which can be obtained from the pyrolysis with 10.0% perlite. The yields of liquid products sharply increase between 3.5 and 6.5min with 2.5% perlite run, whereas 3 and 7min with 10.0% run. Then the yields approach the plateau value after 11 min for all runs. The influence of residence time on the yield of products is small, with a slight decrease in oil yield and increase in char yield. Charcoal yields from 2.5% perlite run were 64.9 and 30.5% for 5 and 20min, respectively.

This article presents a detailed review of thermochemical routes for hydrogen production from biomass as a renewable and alternative energy source. Hydrogen is currently derived from non-renewable natural gas and petroleum, but could, in principle, be generated from renewable resources such as biomass. The production of hydrogen from fossil fuels causes the co-production of CO2, which is assumed to be the main factor responsible for the so-called “greenhouse effect.” The production of hydrogen from biomass has several advantages compared to that of fossil fuels. The methods available for hydrogen production from biomass can be divided into two main categories: thermochemical and biological routes. Hydrogen can be produced from biomass by pyrolysis, gasification, steam gasification, and steam-reforming of bio-oils.

Hydrogen is considered in many countries to be an important alternative energy vector and a bridge to a sustainable energy future. The “hydrogen economy” is being promoted as one of the solutions of the world's energy problems. A hydrogen economy, the long-term goal of many nations, can potentially confer energy security, along with economic and environmental benefits. The Global Hydrogen Vision envisions hydrogen as a flexible, safe, affordable, domestic energy resource to be used in all sectors of the economy and all regions of the world. There are many technical and economic challenges to be overcome before the vision of a hydrogen economy becomes reality. Technical challenges in achieving a hydrogen economy include lowering the cost of hydrogen production, storage, delivery, and end use applications.

World primary energy demand is expected to continue to grow steadily, as it has over the last two decades. To meet this need, the world will have to make the best possible use of the various energy sources available, including coal, the most abundant and affordable of the fossil fuels. Coal is often the only alternative when low-cost, cleaner energy sources are inadequate to meet growing energy demand. Developing countries use about 55% of the world's coal today; this share is expected to grow to 65% over the next 15 years. In the year 2050, coal will account for more than 34% of the world's primary energy demand. The aim of the present article is to investigate the contribution of coal to global energy demand and coal perspectives for several countries.

Natural gas is the second fastest growing energy source after nonhydro renewables. The role of natural gas in the world's energy supply is growing rapidly. Natural gas is one of the most widely used forms of energy today. Natural gas prices are developed for the residential, commercial, industrial, transportation, and electric utility sectors. Natural gas is found around the world, but the largest reserves are in the former Soviet Union and the Middle East. The history of natural gas production and use in the industrial era is dominated by the United States, which accounted for well over 95% of global gas production and use well into the 1930s. The main objective of the present study is to investigate global natural gas demand, supplies, and its share in global energy sources by presenting its historical development.

In the beginning of this new century, the rational use of energy becomes a keyword for the world sustainable development both in developed and developing countries. Geothermal resources have the potential of contributing significantly to sustainable energy use in many parts of the world. Geothermal energy has been used commercially for about one century and its large-scale utilization (hundreds of MW) started about 40 years ago, both for electricity generation and for direct application as space heating and combined with heat pumps. The technology, reliability, economics, and environmental acceptability of direct use of geothermal energy have been demonstrated throughout the world. The aim of the present article is to investigate the contribution of geothermal energy to global energy demand and utilization of geothermal energy.

The aim of the present article is to investigate the increasing electricity consumption with the growth of the economy in Turkey. With its emerging and rapidly growing economy and with a population of 73 million people, Turkey has today become the world's 17th largest economy. The country's electricity consumption has risen rapidly as a result of social and economic development. The electricity industry is a large, high-growth sector in the Turkish economy. The industry contributes significantly to the country's GDP and is a 12 billion US dollars industry at current end-user prices. The sector's share in the Turkish economy has been growing rapidly, given the 8% per annum growth in electricity demand over the past two decades. Total investment required for power plants and distribution lines up until the year 2010 is expected to be around US$45 billion, US$19 billion of which will be under the Build, Operate and Transfer and Build, Own, Operate models.

This article deals with a review of modern wind turbine technology. Wind energy for electricity production today is a mature, competitive, and virtually pollution-free technology widely used in many areas of the world. Wind technology converts the energy available in wind to electricity or mechanical power through the use of wind turbines. A wind turbine is a machine for converting the mechanical energy in wind into electrical energy. Wind turbines capture the power from the wind by means of aerodynamically designed blades and convert it into rotating mechanical power. Wind turbine blades use airfoils to develop mechanical power. Recent advances in technology and performance have resulted in current wind turbine designs being increasingly efficient, cost effective, and reliable.

This article reviews the applications and performance of microbial fuel cells as an alternative energy option. This technology involves using microorganisms, like bacteria, to oxidize biodegradable substrates as fuels through biological processes to produce electrons, which are then shuttled to an external electron acceptor (anode), and transferred to a cathode via copper wire, thus producing electricity. The performance of a microbial fuel cell can be influenced by several factors. The performance of a microbial fuel cell, as well as other fuel cells, is determined by the current, power density, and rate of fuel oxidation. Various factors can influence the rate of fuel oxidation, including the anodic catalytic activity, fuel diffusion, and the diffusion and consumption of electrons and protons. A microbial fuel cell generates electricity directly from electron donors through the microbial activity. Electricity generation in microbial fuel cells is based on the metabolic activity of living microo...

This article reviews biological production processes of hydrogen as a renewable and alternative energy source. Biological hydrogen produced from renewable sources (biomass, water, and organic wastes) either biologically or photo-biologically is called “biohydrogen.” The phenomenon of biological hydrogen production was observed one century ago. When the oil crisis broke out in 1970s, the technology started receiving attention, especially in hydrogen production by photosynthetic process. Biological hydrogen production is one of the alternative methods where processes can be operated at ambient temperatures and pressures, and are less energy intensive and more environmentally friendly. Biological production of hydrogen as a by-product of microorganism metabolism is an exciting new area of technology development that offers the potential production of usable hydrogen from a variety of renewable resources.

As concern about global warming and dependence on fossil fuels grows, the search for renewable energy sources that reduce CO2 emissions becomes a matter of widespread attention. Production of ethanol (bioethanol) from biomass is one way to reduce both the consumption of crude oil and environmental pollution. Using bioethanol-blended fuel for automobiles can significantly reduce petroleum use and exhaust greenhouse gas emission. While more expensive to produce than other fuel types, bioethanol production boosts the farm economy. Up to 80% of production cost is the cost of feedstock. Bioethanol can be produced from cellulose feedstocks such as corn stalks, rice straw, sugar cane bagasse, pulpwood, switchgrass, and municipal solid waste.

The aim of this article is to investigate the contribution of biomass energy to global energy demand and energy production from biomass. Biomass energy plays a vital role in meeting local energy demand in many regions of the developing world. Biomass energy utilization has gained particular interest in recent years due to the progressive depletion of conventional fossil fuels, which calls for an increased use of renewable energy sources. Biomass energy is more economical to produce and it provides more energy than other energy forms. Biomass production is eight times greater than the total annual world consumption of all other energy sources.

This article reviews the production processes and characterization of biogas as an alternative energy source. Biogas, the gas generated from organic digestion under anaerobic conditions by mixed population of microorganisms, is an alternative energy source, which has been commenced to be utilized both in rural and industrial areas at least since 1958. Biogas technology offers a very attractive route to utilize certain categories of biomass for meeting partial energy needs. Unlike other forms of renewable energy, biogas neither has any geographical limitations and required technology for producing energy and it is neither complex or monopolistic.

The aim of the present article is to investigate biodiesel production via transesterification process and effect of reaction parameters on conversion yield. Biodiesel (fatty acid methyl esters) is a notable alternative to the widely used petroleum-derived diesel fuel since it can be generated by domestic natural sources such as soybeans, rapeseeds, coconuts, and even recycled cooking oil, and thus reduces dependence on diminishing petroleum fuel from foreign sources. The problems with substituting triglycerides for diesel fuels are mostly associated with their high viscosities, low volatilities, and polyunsaturated character. The purpose of the transesterification process is to lower the viscosity of the oil.

The aim of this study is to obtain pyrolysis liquid products from waste engine oil in the presence of wood ash. Petroleum-based waste engine oil can be converted into reusable products such as gasoline and diesel fuel. Possible acceptable processes are distillation, cracking, and pyrolysis. Distillation technique is one of the cheapest and most efficient processes experienced in recycling of waste engine oils. The aims of waste engine oil processing are upgrading via recycling and re-refining processes of the petroleum-based wastes by converting them into reusable products such as gasoline and heavy oil. The pyrolysis liquid products of waste engine oil can be used as alternative engine fuel. The highest yield of liquid product was 84.7%, which can be obtained from the pyrolysis with 15% wood ash run.

The aim of this study is to investigate gasification technologies and gasification of biomass for gaseous products. The gasification of biomass is a thermal treatment, which results in a high proportion of gaseous products and small quantities of char (solid product) and ash. At temperatures of approximately 873–1,273 K, solid biomass undergoes thermal decomposition to form gas-phase products that typically include H2, CO, CO2, CH4, H2O, and other gaseous hydrocarbons. Hydrogen gas was produced on a pilot scale by steam gasification of charred cellulosic waste material. The yield from steam gasification increases with increasing water to sample ratio. The yields of hydrogen from the pyrolysis and the steam gasification increase with the increase of temperature. In general, the gasification temperature is higher than that of pyrolysis and the yield of hydrogen from the gasification is higher than that of the pyrolysis.

In this work, development of worldwide green electricity in the past decade period were investigated. Green electricity products have become more attractive recently because of its environmental benefits and the fact that it can be derived from renewable energy resources. Renewable energy resources that use domestic resources have the potential to provide energy services with zero or almost zero emissions of both air pollutants and greenhouse gases. Renewable energy resources are the third largest contributor to global electricity production. Apart from the electricity sector, renewable energy resources for the generation of heat and the use of environmental friendly bio-fuels for the transport sector will become more and more important in the future. Approximately 14% of the world's energy supply comes from renewable energy resources. Renewable energy resources are the third largest contributor to global electricity production. In 2004, global electricity production has reached about 17,387 TWh,...

The aim of the present article is to investigate Turkey's energy demand and the contribution of domestic energy sources to energy consumption. Turkey, the 17th largest economy in the world, is an emerging country with a buoyant economy challenged by a growing demand for energy. Turkey's energy consumption has grown and will continue to grow along with its economy. Turkey's energy consumption is high, but its domestic primary energy sources are oil and natural gas reserves and their production is low. Total primary energy production met about 27% of the total primary energy demand in 2005. Oil has the biggest share in total primary energy consumption. Lignite has the biggest share in Turkey's primary energy production at 45%. Domestic production should be to be nearly doubled by 2010, mainly in coal (lignite), which, at present, accounts for almost half of the total energy production. The hydropower should also increase two-fold over the same period.

Hydrogen is a promising renewable fuel for transportation and domestic applications. Hence, in both the near term and long term, hydrogen demand is expected to increase significantly. Producing hydrogen, as well as any other synthetic fuel, will inevitably cost more energy than pumping up oil or using other fossil fuels. In this work, a review is made of the alternative technological methods that could be used to produce this fuel. Hydrogen can be generated in a number of ways, such as electrochemical processes, thermochemical processes, photochemical processes, photocatalytic processes, or photoelectrochemical processes. The thermal production process, which uses steam to produce hydrogen from natural gas or other light hydrocarbons, is most common. Steam reforming of natural gas is currently the least expensive method of producing hydrogen and is used for about half of the world's production of hydrogen. Approximately 95% of the hydrogen produced today comes from carbonaceous raw material, prim...

Vegetable oils have become more attractive recently because of their environmental benefits and the fact that it is made from renewable resources. Vegetable oils do not contain any sulfur, aromatic hydrocarbons, metals, or crude oil residues. Short-term engine tests indicate good potential for vegetable oil fuels. Long-term endurance tests may show serious problems in injector coking, ring sticking, gum formation, and thickening of the lubricating oil. The high viscosity of vegetable oil reduces fuel atomization and increases fuel spray penetration. The vegetable oils, as alternative engine fuels, are all extremely viscous with viscosities ranging from 10 to 20 times greater than that of petroleum diesel fuel. Modern diesel engines have fuel-injection systems that are sensitive to viscosity changes. A way to avoid these problems is to reduce the viscosity of vegetable oil in order to improve its performance. There are some methods to reduce the viscosity of vegetable oil. The purpose of this work...

This article reviews the liquefaction mechanisms of biomass structural constituents. One pivotal study of such liquefaction processes was done in the 1970s funded by the Bureau of Mines of the United States. Liquefaction is a low-temperature, high-pressure thermochemical process using a catalyst. The process produces a marketable liquid product. In the case of liquefaction, macromolecule compounds in biomass are degraded into small molecules with or without catalyst in the aqueous medium or using organic solvent. Thus, obtained small molecules are unstable and reactive and can repolymerize into oily products with a wide range of molecular weight distribution. In the liquefaction process, the micellar-like broken-down fragments produced by hydrolysis are degraded to smaller compounds by dehydration, dehydrogenation, deoxygenation, and decarboxylation. These compounds once produced, rearrange through condensation, cyclization, and polymerization, leading to new compounds. Thermal depolymerization a...

The present work is a study on the pyrolysis mechanisms of biomass structural constituents. Biomass resources include wood and wood wastes, agricultural crops and their waste byproducts, municipal solid waste, animal wastes, waste from food processing, and aquatic plants and algae. The major organic components of biomass can be classified as cellulose, hemicelluloses, and lignin. The pyrolysis is thermal degradation of biomass by heat in the absence of oxygen, which results in the production of charcoal (solid), bio-oil (liquid), and fuel gas products. Thermal degradation of cellulose proceeds through two types of reaction: a gradual degradation, decomposition, and charring on heating at lower temperatures; and a rapid volatilization accompanied by the formation of levoglucosan on pyrolysis at higher temperatures. The hemicelluloses reacted more readily than cellulose during heating. Of the hemicelluloses, xylan is the least thermally stable, because pentosans are most susceptible to hydrolysis a...

The main objective in doing the present study is to investigate hydrogen production from biomass via pyrolysis and gasification. Hydrogen is currently derived from nonrenewable natural gas and petroleum but could in principle be generated from renewable resources such as biomass. It can be produced from biomass via two thermochemical processes: (1) gasification followed by reforming of the syngas, and (2) fast pyrolysis followed by reforming of the carbohydrate fraction of the bio-oil. Steam reforming of hydrocarbons, partial oxidation of heavy oil residues, selected steam reforming of aromatic compounds, and gasification of coals and solid wastes to yield a mixture of H2 and CO (syngas), followed by water-gas shift conversion to produce H2 and CO2, are well-established processes. The yields of hydrogen from the pyrolysis and the steam gasification increase with increase of temperature. In general, the gasification temperature is higher than that of pyrolysis and the yield of hydrogen from the ga...

This paper reviews the production and characterization of biodiesel fuel from vegetable oils as well as the experimental work carried out via supercritical ethanol transesterification. Biodiesel, which can be used as an alternative diesel fuel, is made from renewable biological sources such as vegetable oil and animal fats. More than 100 years ago, a brilliant inventor named Rudolph Diesel designed the original diesel engine to run on vegetable oil. There are more than 350 oil-bearing crops identified, among which only sunflower, safflower, soybean, cottonseed, rapeseed, and peanut oils are considered as potential alternative fuels for diesel engines. The major problem associated with the use of pure vegetable oils as fuels for diesel engines are caused by high fuel viscosity in compression ignition. Dilution, micro-emulsification, pyrolysis, and transesterification are the four techniques applied to solve the problems encountered with the high fuel viscosity. Dilution of oils with solvents and m...

The aim of present paper is to investigate wind power capacity, markets, and regional plans in the European Union. Wind energy is a clean and renewable source of electricity. The technically availa...

The objective of this study is to determine the lignite use for Turkey's energy necessity. Lignite is the most important energy resource of Turkey when compared with others according to the amount of reserves. Lignite is the dominant source of energy produced (43%) in Turkey. Lignite deposits are encountered in almost every region of Turkey. Total lignite reserves are estimated at 8,375 million tons, of which 7,340 million tons (88%) is economically feasible. Share of lignite reserves of Turkey are 2% in the world. Lignite deposits are encountered in almost every region of Turkey. Afsin-Elbistan, Mugla, Soma, Tuncbilek, Seyitomer, Beypazari and Sivas basins constitutes the most important known lignite reserves. The biggest lignite deposits, 40% of the total, are in Afsin-Elbistan. Lignite extraction is expected to increase as the government feels pressure to close down unprofitable hard coal mines that are geologically difficult, increasing the cost of extraction.

Turkey's energy consumption has been growing much faster than its energy production, making Turkey a rapidly growing energy importer. Crude oil remains the main energy source. Oil provides nearly half of Turkey's total energy requirements, but its share is declining. Around 90% of Turkey's oil supplies are imported, mainly from the Middle East (Saudi Arabia, Iran, Iraq, Syria) and Russia. Exploration and production and importing of crude oil and petroleum products are liberalized. Indigenous and foreign companies are also allowed to operate refineries and to distribute oil products. Until recently, there were six petroleum refineries in Turkey with a total production capacity of 32 million tons/year for crude oil. Most of the oil refining in Turkey is done by the Turkish Petroleum Refineries Corporation (TUPRAS), which owns four of the six oil refineries in Turkey. Turkey's petroleum products consumption quantity also grew 36% and increased from 21.7 million tons (Mt) in 1990 to 29.6 Mt in 2004. ...

Nuclear technology plays an important role in medicine, industry, science, food and agriculture, and power generation. Nuclear power plants (NPPs) are structured like other power plants, except that they use energy from nuclear fission to produce electricity. Nuclear energy is a very clean energy if it is well designed, well built, well operated, and well managed. It has no atmospheric emissions or pollution (or close to none), is compact, produces little waste (and this is confined and self-degradable), and avoids increasing the greenhouse effect. Although fewer NPPs are being built now than during the 1970s and 1980s, those operating are producing more electricity. Advocates of nuclear energy for sustainable development argue that it is a well-established noncarbon technology, as demonstrated by its 16% share of the world's electricity supply and even higher share in specific countries, e.g., 78.5% in France.

The aim of this work is to investigate influence of fossil energy applications on the environmental pollution. Turkey's high rate of economic growth experienced during much of the 1990s, besides resulting in booming industrial production, also led to higher levels of energy consumption, imports, air and water pollution, and greater risks to the country's environment. Air pollution is a major problem in Turkey, with key pollutants including sulfur dioxide, suspended particulates, nitrogen oxides, and carbon dioxide. In Turkey, carbon dioxide emissions from fossil fuels totaled about 50.07 million tons in 2001. However, fuel share of carbon emissions in 2001 was oil 44.2%, coal 38.8%, and natural gas 16.9%. Total carbon dioxide emissions from fossil fuels are expected to be 104 million tons in 2025.

The purpose of this work is to investigate biodiesel production processes from vegetable oils. Biodiesel fuel can be made from new or used vegetable oils and animal fats, which are non-toxic, biodegradable, renewable resources. The vegetable oil fuels were not acceptable because they were more expensive than petroleum fuels. Biodiesel has become more attractive recently because of its environmental benefits. With recent increases in petroleum prices and uncertainties concerning petroleum availability, there is renewed interest in vegetable oil fuels for diesel engines. Dilution of oils with solvents and microemulsions of vegetable oils lowers the viscosity, and some engine performance problems still exist. The purpose of the transesterification process is to lower the viscosity of the oil. Pyrolysis produces more biogasoline than biodiesel fuel.

Hydrogen is not a primary fuel; it must be manufactured from water with either fossil or nonfossil energy sources. Benefits include cleaner air, cleaner water, and better health. Hydrogen can be used as a engine fuel, whereas neither nuclear nor solar energy can be used directly. It has good properties as a fuel for internal combustion engines in automobiles. The main disadvantages of using hydrogen as a fuel for automobiles are huge on-board storage tanks which are required because of hydrogen's extremely low density. Hydrogen will also solve air pollution and planet-warming problems in the future. The combustion of hydrogen does not produce CO2, CO, SO2, VOC and particles, but entails emission of vapor and NOx.

Biofuels are liquid or gaseous fuels made from plant matter and residues, such as agricultural crops, municipal wastes and agricultural and forestry by-products. The term biofuels can refer to fuels for direct combustion for electricity production, but is generally used for liquid fuels for transportation. Biofuels are made from biomass through biochemical or thermochemical processes. Currently much attention is fo cused on utilization of ethanol, methanol, biodiesel, biocrude, and methane as biofuels. The European Union is on the third rank of biofuel production world wide, behind Brazil and the United States. In Europe, Germany is the largest, and France the second largest producer of biofuels. Most biofuels in commercial production in Europe today are based on sugar beet, wheat and rapeseed, which are converted to bioethanol/ETBE and biodiesel. The European Commission has set as a goal that by the end of 2005, 2% of the energy used in transportation shall be biofuels. The use of biofuels is th...

This article deals with recently status of global fossil energy sources. Fossil energy sources have been split into three categories: oil, coal, and natural gas. Fossil fuels are highly efficient and cheap. Currently oil is the fastest primary energy source in the world (39% of world energy consumption). Coal will be a major source of energy for the world for the foreseeable future (24% of world energy consumption). In 2030, coal covers 45% of world energy needs. Natural gas is expected to be the fastest growing component of world energy consumption (23% of world energy consumption). Fossil fuel extraction and conversion to usable energy has several environmental impacts. They could be a major contributor to global warming and greenhouse gases and a cause of acid rain; therefore, expensive air pollution controls are required.

This article considers the influence of coal energy on environmental pollution. Coal is undoubtedly part of the greenhouse problem. The main emissions from coal combustion are sulfur dioxide (SO2), nitrogen oxides (NOx), particulates, carbon dioxide (CO2), and mercury (Hg). Since 1980, despite a 36% increase in electricity generation and more than a 50% increase in coal use, electric utility SO2 and NOx emissions have declined significantly. Globally, the largest source of anthropogenic greenhouse gas (GHG) emissions is CO2 from the combustion of fossil fuels—around 75% of total GHG emissions covered under the Kyoto Protocol. At the present time, coal is responsible for 30–40% of world CO2 emission from fossil fuels.

Boron fuel is made up of the element boron. Boron as a chemical fuel will be a promising engine fuel in the future. Cars in which boron fuel simply burns will be true zero emission vehicles. Total world production of boron minerals was approximately 4,270,000 tons in 2000. Turkey has the largest boron sources in the world. It is estimated that about 64% of the known reserves are in Turkey, which has a substantial boron extraction industry. The amount of this resource is about 2.5 million tons and has high tenor and quality.